diff --git a/apps/control-station/package-lock.json b/apps/control-station/package-lock.json
index bf469d0..4a680ed 100644
--- a/apps/control-station/package-lock.json
+++ b/apps/control-station/package-lock.json
@@ -7,7 +7,9 @@
     "": {
       "name": "@nodedc/mission-core-control-station",
       "version": "0.1.0",
+      "hasInstallScript": true,
       "dependencies": {
+        "@noble/hashes": "^2.2.0",
         "@nodedc/tokens": "file:../../../NODEDC_DESIGN_GUIDELINE/packages/tokens",
         "@nodedc/ui-core": "file:../../../NODEDC_DESIGN_GUIDELINE/packages/ui-core",
         "@nodedc/ui-react": "file:../../../NODEDC_DESIGN_GUIDELINE/packages/ui-react",
@@ -834,6 +836,18 @@
         "@jridgewell/sourcemap-codec": "^1.4.14"
       }
     },
+    "node_modules/@noble/hashes": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/@noble/hashes/-/hashes-2.2.0.tgz",
+      "integrity": "sha512-IYqDGiTXab6FniAgnSdZwgWbomxpy9FtYvLKs7wCUs2a8RkITG+DFGO1DM9cr+E3/RgADRpFjrKVaJ1z6sjtEg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 20.19.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
     "node_modules/@nodedc/tokens": {
       "resolved": "../../../NODEDC_DESIGN_GUIDELINE/packages/tokens",
       "link": true
diff --git a/apps/control-station/package.json b/apps/control-station/package.json
index 32220e3..3c5e022 100644
--- a/apps/control-station/package.json
+++ b/apps/control-station/package.json
@@ -4,6 +4,7 @@
   "private": true,
   "type": "module",
   "scripts": {
+    "postinstall": "node scripts/patch-rerun-web-viewer.mjs",
     "dev": "vite",
     "build": "tsc -b && vite build",
     "preview": "vite preview",
@@ -11,6 +12,7 @@
     "typecheck": "tsc -b --pretty false"
   },
   "dependencies": {
+    "@noble/hashes": "^2.2.0",
     "@nodedc/tokens": "file:../../../NODEDC_DESIGN_GUIDELINE/packages/tokens",
     "@nodedc/ui-core": "file:../../../NODEDC_DESIGN_GUIDELINE/packages/ui-core",
     "@nodedc/ui-react": "file:../../../NODEDC_DESIGN_GUIDELINE/packages/ui-react",
diff --git a/apps/control-station/scripts/patch-rerun-web-viewer.mjs b/apps/control-station/scripts/patch-rerun-web-viewer.mjs
new file mode 100644
index 0000000..9b780c4
--- /dev/null
+++ b/apps/control-station/scripts/patch-rerun-web-viewer.mjs
@@ -0,0 +1,61 @@
+import { readFileSync, writeFileSync } from "node:fs";
+import { dirname, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const root = resolve(dirname(fileURLToPath(import.meta.url)), "..");
+const packageRoot = resolve(root, "node_modules/@rerun-io/web-viewer");
+const manifest = JSON.parse(readFileSync(resolve(packageRoot, "package.json"), "utf8"));
+
+if (manifest.version !== "0.34.1") {
+  throw new Error(
+    `Refusing to patch @rerun-io/web-viewer ${manifest.version}; audit the new vendor lifecycle first.`,
+  );
+}
+
+const patches = [
+  {
+    label: "compiled watchdog",
+    path: resolve(packageRoot, "index.js"),
+    before: `        function check_for_panic() {\n            if (self.#handle?.has_panicked()) {`,
+    after: `        function check_for_panic() {\n            if (self.#state !== "ready" || !self.#handle) {\n                return;\n            }\n            if (self.#handle.has_panicked()) {`,
+  },
+  {
+    label: "source watchdog",
+    path: resolve(packageRoot, "index.ts"),
+    before: `    function check_for_panic() {\n      if (self.#handle?.has_panicked()) {`,
+    after: `    function check_for_panic() {\n      if (self.#state !== "ready" || !self.#handle) {\n        return;\n      }\n      if (self.#handle.has_panicked()) {`,
+  },
+  {
+    label: "compiled singleton global listener",
+    path: resolve(packageRoot, "index.js"),
+    before: `function setupGlobalEventListeners() {\n    window.addEventListener("keyup", (e) => {`,
+    after: `let globalEventListenersInstalled = false;\nfunction setupGlobalEventListeners() {\n    if (globalEventListenersInstalled) {\n        return;\n    }\n    globalEventListenersInstalled = true;\n    window.addEventListener("keyup", (e) => {`,
+  },
+  {
+    label: "source singleton global listener",
+    path: resolve(packageRoot, "index.ts"),
+    before: `function setupGlobalEventListeners() {\n  window.addEventListener("keyup", (e) => {`,
+    after: `let globalEventListenersInstalled = false;\nfunction setupGlobalEventListeners() {\n  if (globalEventListenersInstalled) {\n    return;\n  }\n  globalEventListenersInstalled = true;\n  window.addEventListener("keyup", (e) => {`,
+  },
+];
+
+for (const patch of patches) {
+  const source = readFileSync(patch.path, "utf8");
+  if (source.includes(patch.after)) continue;
+  if (!source.includes(patch.before)) {
+    throw new Error(`Vendor ${patch.label} patch no longer matches ${patch.path}.`);
+  }
+  writeFileSync(patch.path, source.replace(patch.before, patch.after));
+}
+
+for (const path of [resolve(packageRoot, "index.js"), resolve(packageRoot, "index.ts")]) {
+  const source = readFileSync(path, "utf8");
+  const keyupListenerCount = source.split('window.addEventListener("keyup"').length - 1;
+  if (!source.includes("let globalEventListenersInstalled = false;") || keyupListenerCount !== 1) {
+    throw new Error(`Vendor singleton global listener verification failed for ${path}.`);
+  }
+}
+
+console.log(
+  "Patched @rerun-io/web-viewer 0.34.1 watchdog teardown and singleton global keyup listener.",
+);
diff --git a/apps/control-station/src/App.tsx b/apps/control-station/src/App.tsx
index a0c5609..a087e61 100644
--- a/apps/control-station/src/App.tsx
+++ b/apps/control-station/src/App.tsx
@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useMemo, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import {
   AdminNavigationPanel,
   AppHeader,
@@ -26,10 +26,25 @@ import {
 } from "@nodedc/ui-react";
 
 import { LandingStage } from "./components/LandingStage";
+import { ObservationSessionSelect } from "./components/ObservationSessionSelect";
 import { useDevicePluginHost } from "./core/device-plugins/DevicePluginHost";
 import { useMissionRuntime } from "./core/runtime/MissionRuntimeContext";
 import type { ViewerSettings } from "./core/runtime/contracts";
+import {
+  createLatestAsyncCommitter,
+  type LatestAsyncCommitter,
+} from "./core/runtime/latestAsyncCommitter";
 import { useObservationLayout } from "./core/observation/useObservationLayout";
+import { recordedObservationSources } from "./core/observation/recordedObservationSources";
+import type { ObservationSessionReplayLaunch } from "./core/observation/sessionArchive";
+import { useRecordedSessionAdmission } from "./core/observation/useRecordedSessionAdmission";
+import { useWorkspaceLayoutProfile } from "./core/observation/useWorkspaceLayoutProfile";
+import {
+  OBSERVATION_WORKSPACE_ID,
+  OBSERVATION_WORKSPACE_LAYOUT_VERSION,
+  type ObservationToolWindowId,
+  type ObservationWorkspaceLayoutProfile,
+} from "./core/observation/workspaceLayout";
 import {
   rootById,
   roots,
@@ -48,7 +63,10 @@ import { DeviceWorkspace } from "./workspaces/DeviceWorkspace";
 import { WorkspaceRenderer } from "./workspaces/Workspaces";
 import "./styles/scene-windows.css";
 
-type SceneToolWindowId = "sources" | "display" | "layers" | "layout";
+type SceneToolWindowId = ObservationToolWindowId;
+
+const sceneToolWindowIds: readonly SceneToolWindowId[] = ["sources", "display", "layers"];
+const viewerSettingsQuietPeriodMs = 750;
 
 const colorModeOptions: Array<{ value: PointColorMode; label: string; description: string }> = [
   { value: "intensity", label: "Интенсивность", description: "Значение отражённого сигнала" },
@@ -116,28 +134,117 @@ export default function App() {
 
   const [activeRoot, setActiveRoot] = useState<RootId | null>(null);
   const [sourceUrl, setSourceUrl] = useState("");
+  const [recordedReplay, setRecordedReplay] = useState<ObservationSessionReplayLaunch | null>(null);
+  const [replayTransitioning, setReplayTransitioning] = useState(false);
   const [sourceDraft, setSourceDraft] = useState("");
   const [sourceWindowOpen, setSourceWindowOpen] = useState(false);
   const [displayWindowOpen, setDisplayWindowOpen] = useState(false);
   const [layerInspectorOpen, setLayerInspectorOpen] = useState(false);
   const [sceneWindowOrder, setSceneWindowOrder] = useState<SceneToolWindowId[]>([]);
-  const [layoutWindowOpen, setLayoutWindowOpen] = useState(false);
-  const [layoutName, setLayoutName] = useState("Операторская сцена");
-  const [layoutDraftSaved, setLayoutDraftSaved] = useState(false);
+  const [layoutSaveNotice, setLayoutSaveNotice] = useState<string | null>(null);
   const [sceneSettings, setSceneSettings] = useState<SceneSettings>(defaultSceneSettings);
   const [displayDraft, setDisplayDraft] = useState<SceneSettings>(defaultSceneSettings);
+  const appliedProfileKeyRef = useRef<string | null>(null);
+  const sceneSettingsRef = useRef<SceneSettings>(defaultSceneSettings);
+  const displayDraftRef = useRef<SceneSettings>(defaultSceneSettings);
+  const confirmedSceneSettingsRef = useRef<SceneSettings>(defaultSceneSettings);
+  const viewerSettingsCommitTimerRef = useRef<number | null>(null);
+  const runtimeUpdateViewerSettingsRef = useRef(runtime.updateViewerSettings);
+  const replayActiveRef = useRef(false);
+  const sceneSettingsCommitterActiveRef = useRef(true);
+  const sceneSettingsCommitterRef = useRef<LatestAsyncCommitter<SceneSettings> | null>(null);
 
   const currentRoot = rootById(activeRoot);
   const activeDefinition = workspaceById(workspace.activeView);
   const rootWorkspaces = workspacesForRoot(activeRoot);
   const activeSceneWindow = sceneWindowOrder[sceneWindowOrder.length - 1] ?? null;
   const automaticSourceUrl = runtime.state?.spatialSource?.url.trim() ?? "";
-  const effectiveSourceUrl = sourceUrl || automaticSourceUrl;
-  const observationLayout = useObservationLayout(
-    runtime.state?.observationSources ?? [],
-    runtime.setObservationSourceActive,
+  const effectiveSourceUrl = replayTransitioning ? "" : sourceUrl || automaticSourceUrl;
+  const replayActive = Boolean(recordedReplay && sourceUrl === recordedReplay.sourceUrl);
+  const recordedSessionAdmission = useRecordedSessionAdmission(
+    replayActive ? recordedReplay : null,
   );
-  const focusedObservationSource = runtime.state?.observationSources?.find(
+  const displayPaletteOptions = replayActive
+    ? paletteOptions.map((option) => {
+        if (option.value === "turbo") {
+          return {
+            ...option,
+            label: "Цвет записи",
+            description: "Вернуть цвета, сохранённые внутри RRD",
+          };
+        }
+        return option.value === "custom" ? option : { ...option, disabled: true };
+      })
+    : paletteOptions;
+  runtimeUpdateViewerSettingsRef.current = runtime.updateViewerSettings;
+  replayActiveRef.current = replayActive;
+
+  if (!sceneSettingsCommitterRef.current) {
+    sceneSettingsCommitterRef.current = createLatestAsyncCommitter<SceneSettings>({
+      commit: (settings) => replayActiveRef.current
+        ? Promise.resolve(true)
+        : runtimeUpdateViewerSettingsRef.current(toViewerSettings(settings)),
+      onSettled: ({ value, applied, superseded }) => {
+        if (!sceneSettingsCommitterActiveRef.current) return;
+        if (applied) confirmedSceneSettingsRef.current = value;
+        if (superseded) return;
+
+        const next = applied ? value : confirmedSceneSettingsRef.current;
+        sceneSettingsRef.current = next;
+        setSceneSettings(next);
+        if (!applied && displayDraftRef.current === value) {
+          displayDraftRef.current = next;
+          setDisplayDraft(next);
+        }
+      },
+    });
+  }
+  const replaySources = useMemo(
+    () => recordedObservationSources(recordedReplay),
+    [recordedReplay],
+  );
+  const activeObservationSources = replayActive
+    ? replaySources
+    : runtime.state?.observationSources ?? [];
+  const activeRuntimeState = useMemo(() => {
+    if (!replayActive || !recordedReplay) return runtime.state;
+    return {
+      ...(runtime.state ?? { phase: "replaying" as const }),
+      phase: "replaying" as const,
+      sourceMode: "replay" as const,
+      spatialSource: {
+        id: "recorded.spatial.primary",
+        url: recordedReplay.sourceUrl,
+        label: "Сохранённая пространственная сцена",
+        kind: "rrd" as const,
+      },
+      observationSources: replaySources,
+      observationTimeline: {
+        mode: "recorded" as const,
+        seekable: true,
+        sessionRecording: true,
+        synchronization: "host-arrival-best-effort" as const,
+        range: {
+          startSeconds: recordedReplay.timelineStartSeconds,
+          endSeconds: recordedReplay.timelineEndSeconds,
+        },
+      },
+    };
+  }, [recordedReplay, replayActive, replaySources, runtime.state]);
+  const viewerSettingsTargetIdentity = [
+    runtime.state?.activeDevice?.pluginId,
+    runtime.state?.activeDevice?.modelId,
+    runtime.state?.activeDevice?.instanceId,
+    runtime.state?.deviceSession?.sessionId,
+    runtime.state?.deviceSession?.deviceId,
+    runtime.state?.acquisition?.acquisitionId,
+  ].filter(Boolean).join(":") || "local-runtime";
+  const observationLayout = useObservationLayout(
+    activeObservationSources,
+    replayActive ? undefined : runtime.setObservationSourceActive,
+  );
+  const workspaceLayoutProfile = useWorkspaceLayoutProfile();
+  const focusedObservationSource = activeObservationSources.find(
     (source) => source.id === observationLayout.focusedSourceId,
   );
   const observationFullscreenActive = Boolean(
@@ -148,12 +255,80 @@ export default function App() {
 
   useEffect(() => {
     const remote = runtime.state?.viewerSettings;
-    if (!remote) return;
-    setSceneSettings((current) => mergeViewerSettings(current, remote));
-    if (!displayWindowOpen) {
-      setDisplayDraft((current) => mergeViewerSettings(current, remote));
+    if (
+      !remote ||
+      workspaceLayoutProfile.profile ||
+      sceneSettingsCommitterRef.current?.isBusy()
+    ) return;
+    const merged = mergeViewerSettings(sceneSettingsRef.current, remote);
+    sceneSettingsRef.current = merged;
+    confirmedSceneSettingsRef.current = merged;
+    setSceneSettings(merged);
+    if (viewerSettingsCommitTimerRef.current === null) {
+      displayDraftRef.current = merged;
+      setDisplayDraft(merged);
     }
-  }, [runtime.state?.viewerSettings, displayWindowOpen]);
+  }, [runtime.state?.viewerSettings, workspaceLayoutProfile.profile]);
+
+  useEffect(() => {
+    const profile = workspaceLayoutProfile.profile;
+    if (!profile) return;
+    if (viewerSettingsCommitTimerRef.current !== null) {
+      window.clearTimeout(viewerSettingsCommitTimerRef.current);
+      viewerSettingsCommitTimerRef.current = null;
+    }
+    sceneSettingsRef.current = profile.sceneSettings;
+    displayDraftRef.current = profile.sceneSettings;
+    confirmedSceneSettingsRef.current = profile.sceneSettings;
+    setSceneSettings(profile.sceneSettings);
+    setDisplayDraft(profile.sceneSettings);
+    setSourceWindowOpen(profile.toolWindows.sourcesOpen);
+    setDisplayWindowOpen(profile.toolWindows.displayOpen);
+    setLayerInspectorOpen(profile.toolWindows.layersOpen);
+    setSceneWindowOrder(profile.toolWindows.order.filter((windowId) => {
+      if (windowId === "sources") return profile.toolWindows.sourcesOpen;
+      if (windowId === "display") return profile.toolWindows.displayOpen;
+      return profile.toolWindows.layersOpen;
+    }));
+    observationLayout.restore(profile);
+  }, [observationLayout.restore, workspaceLayoutProfile.profile]);
+
+  useEffect(() => {
+    sceneSettingsCommitterActiveRef.current = true;
+    return () => {
+      sceneSettingsCommitterActiveRef.current = false;
+      if (viewerSettingsCommitTimerRef.current !== null) {
+        window.clearTimeout(viewerSettingsCommitTimerRef.current);
+        viewerSettingsCommitTimerRef.current = null;
+      }
+    };
+  }, []);
+
+  useEffect(() => {
+    const profile = workspaceLayoutProfile.profile;
+    const applicationKey = profile
+      ? `${profile.revision}:${viewerSettingsTargetIdentity}`
+      : null;
+    if (
+      !profile ||
+      runtime.backendStatus !== "online" ||
+      !applicationKey ||
+      appliedProfileKeyRef.current === applicationKey
+    ) {
+      return;
+    }
+    appliedProfileKeyRef.current = applicationKey;
+    void runtime.updateViewerSettings(toViewerSettings(profile.sceneSettings)).then((applied) => {
+      if (!applied && appliedProfileKeyRef.current === applicationKey) {
+        appliedProfileKeyRef.current = null;
+      }
+    });
+  }, [
+    runtime.backendStatus,
+    runtime.updateViewerSettings,
+    viewerSettingsTargetIdentity,
+    workspaceLayoutProfile.profile,
+  ]);
 
   const activateSceneWindow = useCallback((windowId: SceneToolWindowId) => {
     setSceneWindowOrder((current) => [
@@ -166,7 +341,6 @@ export default function App() {
     if (windowId === "sources") setSourceWindowOpen(false);
     if (windowId === "display") setDisplayWindowOpen(false);
     if (windowId === "layers") setLayerInspectorOpen(false);
-    if (windowId === "layout") setLayoutWindowOpen(false);
     setSceneWindowOrder((current) => current.filter((candidate) => candidate !== windowId));
   }, []);
 
@@ -204,8 +378,41 @@ export default function App() {
     activateSceneWindow("sources");
   };
 
+  const commitDisplaySettings = useCallback((next: SceneSettings) => {
+    if (viewerSettingsCommitTimerRef.current !== null) {
+      window.clearTimeout(viewerSettingsCommitTimerRef.current);
+      viewerSettingsCommitTimerRef.current = null;
+    }
+    displayDraftRef.current = next;
+    setDisplayDraft(next);
+    sceneSettingsCommitterRef.current?.enqueue(next);
+  }, []);
+
+  const stageDisplayPatch = useCallback((patch: Partial<SceneSettings>) => {
+    const next = { ...displayDraftRef.current, ...patch };
+    displayDraftRef.current = next;
+    setDisplayDraft(next);
+    if (viewerSettingsCommitTimerRef.current !== null) {
+      window.clearTimeout(viewerSettingsCommitTimerRef.current);
+    }
+    viewerSettingsCommitTimerRef.current = window.setTimeout(() => {
+      viewerSettingsCommitTimerRef.current = null;
+      sceneSettingsCommitterRef.current?.enqueue(displayDraftRef.current);
+    }, viewerSettingsQuietPeriodMs);
+  }, []);
+
+  const flushDisplaySettings = useCallback(() => {
+    if (viewerSettingsCommitTimerRef.current === null) return;
+    window.clearTimeout(viewerSettingsCommitTimerRef.current);
+    viewerSettingsCommitTimerRef.current = null;
+    sceneSettingsCommitterRef.current?.enqueue(displayDraftRef.current);
+  }, []);
+
+  const commitDisplayPatch = useCallback((patch: Partial<SceneSettings>) => {
+    commitDisplaySettings({ ...displayDraftRef.current, ...patch });
+  }, [commitDisplaySettings]);
+
   const openDisplay = () => {
-    setDisplayDraft(sceneSettings);
     setDisplayWindowOpen(true);
     activateSceneWindow("display");
   };
@@ -215,28 +422,90 @@ export default function App() {
     activateSceneWindow("layers");
   };
 
-  const openLayout = () => {
-    setLayoutDraftSaved(false);
-    setLayoutWindowOpen(true);
-    activateSceneWindow("layout");
-  };
+  const beginRecordedReplaySwitch = useCallback(async () => {
+    // useObservationSessions calls this only after backend preparation has
+    // produced a validated launch descriptor. Keep the old scene mounted
+    // before this point; now perform one controlled receiver teardown before
+    // accepting the already-ready archive.
+    setReplayTransitioning(true);
+    setRecordedReplay(null);
+    setSourceUrl("");
+    setSourceDraft("");
+    await new Promise<void>((resolve) => {
+      window.requestAnimationFrame(() => window.setTimeout(resolve, 0));
+    });
+  }, []);
 
-  const applyDisplaySettings = async () => {
-    const applied = await runtime.updateViewerSettings(toViewerSettings(displayDraft));
-    if (applied) setSceneSettings(displayDraft);
-  };
+  const acceptRecordedReplay = useCallback((launch: ObservationSessionReplayLaunch) => {
+    setRecordedReplay(launch);
+    setSourceUrl(launch.sourceUrl);
+    setSourceDraft(launch.sourceUrl);
+    setReplayTransitioning(false);
+  }, []);
 
-  const applyScenePatch = async (patch: Partial<SceneSettings>) => {
-    const previous = sceneSettings;
-    const next = { ...sceneSettings, ...patch };
-    setSceneSettings(next);
-    setDisplayDraft((current) => (displayWindowOpen ? { ...current, ...patch } : next));
-    const applied = await runtime.updateViewerSettings(toViewerSettings(next));
-    if (!applied) {
-      setSceneSettings(previous);
-      if (!displayWindowOpen) setDisplayDraft(previous);
+  const settleRecordedReplaySwitch = useCallback((outcome: "accepted" | "error" | "cancelled") => {
+    if (outcome !== "accepted") setReplayTransitioning(false);
+  }, []);
+
+  useEffect(() => {
+    // ObservationSessionSelect owns the cancellable request and unmounts when
+    // the operator leaves the spatial workspace. Its unmount cannot safely
+    // call back into this owner, so clear the transient blanking state here.
+    // Returning to Observation then starts from a deterministic idle source
+    // instead of an orphaned `replayTransitioning=true` state.
+    if (activeDefinition?.kind !== "spatial") setReplayTransitioning(false);
+  }, [activeDefinition?.kind]);
+
+  const applyScenePatch = (patch: Partial<SceneSettings>) => commitDisplayPatch(patch);
+
+  const saveWorkspaceLayout = useCallback(async () => {
+    flushDisplaySettings();
+    await sceneSettingsCommitterRef.current?.waitForIdle();
+
+    const layout = observationLayout.snapshot();
+    if (!layout) {
+      setLayoutSaveNotice("Сцена ещё не измерила рабочую область.");
+      return;
     }
-  };
+    const openWindowOrder = sceneWindowOrder.filter((windowId) => {
+      if (windowId === "sources") return sourceWindowOpen;
+      if (windowId === "display") return displayWindowOpen;
+      return layerInspectorOpen;
+    });
+    const completeWindowOrder = [
+      ...sceneToolWindowIds.filter((windowId) => !openWindowOrder.includes(windowId)),
+      ...openWindowOrder,
+    ];
+    const draft: ObservationWorkspaceLayoutProfile = {
+      version: OBSERVATION_WORKSPACE_LAYOUT_VERSION,
+      revision: workspaceLayoutProfile.profile?.revision ?? 0,
+      workspaceId: OBSERVATION_WORKSPACE_ID,
+      sceneSettings: sceneSettingsRef.current,
+      toolWindows: {
+        sourcesOpen: sourceWindowOpen,
+        displayOpen: displayWindowOpen,
+        layersOpen: layerInspectorOpen,
+        order: completeWindowOrder,
+      },
+      ...layout,
+    };
+    const saved = await workspaceLayoutProfile.save(draft);
+    setLayoutSaveNotice(saved ? "Компоновка сохранена" : workspaceLayoutProfile.error);
+  }, [
+    displayWindowOpen,
+    flushDisplaySettings,
+    layerInspectorOpen,
+    observationLayout.snapshot,
+    sceneWindowOrder,
+    sourceWindowOpen,
+    workspaceLayoutProfile,
+  ]);
+
+  useEffect(() => {
+    if (!layoutSaveNotice || layoutSaveNotice !== "Компоновка сохранена") return;
+    const timer = window.setTimeout(() => setLayoutSaveNotice(null), 2600);
+    return () => window.clearTimeout(timer);
+  }, [layoutSaveNotice]);
 
   const contentActions = useMemo<ApplicationPanelUtilityAction[]>(() => {
     const actions: ApplicationPanelUtilityAction[] = [];
@@ -251,25 +520,27 @@ export default function App() {
 
     if (activeDefinition?.kind === "spatial") {
       actions.push(
+        {
+          label: workspaceLayoutProfile.state === "saving"
+            ? "Сохраняем компоновку"
+            : "Сохранить компоновку",
+          icon: "save",
+          disabled: workspaceLayoutProfile.state === "saving",
+          onClick: () => void saveWorkspaceLayout(),
+        },
         { label: "Настроить визуальный движок", icon: "network", onClick: openSource },
         { label: "Настроить отображение", icon: "sliders", onClick: openDisplay },
         { label: "Открыть слои", icon: "list", onClick: openLayers },
       );
     }
 
-    actions.push({
-      label: "Сохранить компоновку",
-      icon: "save",
-      onClick: openLayout,
-    });
     return actions;
-  }, [activeDefinition?.kind, runtime, sceneSettings, sourceUrl]);
+  }, [activeDefinition?.kind, runtime, saveWorkspaceLayout, workspaceLayoutProfile.state]);
 
   const header = (
     <AppHeader
       brand={<img src="/nodedc-logo.svg" alt="NODE.DC" />}
       brandLabel="NODEDC MISSION CORE"
-      left={<span className="station-label">MISSION CORE</span>}
       center={
         <>
           <HeaderWorkspace kind="mark" label="Mission Core" imageUrl="/nodedc-mark.svg" />
@@ -363,9 +634,29 @@ export default function App() {
                   {phaseLabel(runtime.state?.phase)}
                 </StatusBadge>
               ) : activeDefinition.kind === "spatial" ? (
-                <StatusBadge tone={effectiveSourceUrl ? "accent" : "warning"}>
-                  {effectiveSourceUrl ? "Источник назначен" : "Без источника"}
-                </StatusBadge>
+                <div className="observation-header-tools">
+                  <ObservationSessionSelect
+                    limit={3}
+                    disabled={runtime.pendingAction !== null}
+                    onReplayBegin={beginRecordedReplaySwitch}
+                    onReplayAccepted={(_session, launch) => acceptRecordedReplay(launch)}
+                    onReplaySettled={(_session, outcome) => settleRecordedReplaySwitch(outcome)}
+                  />
+                  {layoutSaveNotice || workspaceLayoutProfile.error ? (
+                    <span
+                      className="workspace-layout-feedback"
+                      data-error={workspaceLayoutProfile.error ? "true" : undefined}
+                      role={workspaceLayoutProfile.error ? "alert" : "status"}
+                    >
+                      <i
+                        className="api-dot"
+                        data-status={workspaceLayoutProfile.error ? "error" : "online"}
+                        aria-hidden="true"
+                      />
+                      {layoutSaveNotice || workspaceLayoutProfile.error}
+                    </span>
+                  ) : null}
+                </div>
               ) : (
                 <StatusBadge tone="warning">Интерфейс готов</StatusBadge>
               )
@@ -380,10 +671,16 @@ export default function App() {
             ) : (
               <WorkspaceRenderer
                 definition={activeDefinition}
-                state={runtime.state}
+                state={activeRuntimeState}
                 backendStatus={runtime.backendStatus}
                 sourceUrl={effectiveSourceUrl}
+                recordedReplay={replayActive ? recordedReplay : null}
+                recordedSessionAdmission={recordedSessionAdmission}
                 sceneSettings={sceneSettings}
+                accumulationSeconds={displayDraft.accumulationSeconds}
+                onAccumulationChange={(accumulationSeconds) =>
+                  stageDisplayPatch({ accumulationSeconds })}
+                onAccumulationCommit={flushDisplaySettings}
                 observationLayout={observationLayout}
                 navigation={{
                   openView,
@@ -419,6 +716,7 @@ export default function App() {
               onClick={() => {
                 setSourceDraft("");
                 setSourceUrl("");
+                setRecordedReplay(null);
               }}
             >
               Сбросить адрес
@@ -429,6 +727,7 @@ export default function App() {
               disabled={!sourceDraft.trim()}
               onClick={() => {
                 setSourceUrl(sourceDraft.trim());
+                setRecordedReplay(null);
               }}
             >
               Применить адрес
@@ -530,21 +829,6 @@ export default function App() {
         data-scene-active={activeSceneWindow === "display" ? "true" : undefined}
         onPointerDown={() => activateSceneWindow("display")}
         onClose={() => closeSceneWindow("display")}
-        footer={
-          <WindowFooterActions>
-            <Button variant="ghost" onClick={() => setDisplayDraft(defaultSceneSettings)}>
-              Сбросить
-            </Button>
-            <Button
-              variant="primary"
-              shape="pill"
-              disabled={runtime.pendingAction === "viewer"}
-              onClick={() => void applyDisplaySettings()}
-            >
-              {runtime.pendingAction === "viewer" ? "Применяем…" : "Применить к сцене"}
-            </Button>
-          </WindowFooterActions>
-        }
       >
         <Inspector
           defaultOpen={["points"]}
@@ -556,41 +840,66 @@ export default function App() {
               description: "Размер и способ окрашивания",
               content: (
                 <div className="inspector-control-stack">
-                  <RangeControl
-                    label="Размер точки"
-                    value={displayDraft.pointSize}
-                    min={0.5}
-                    max={12}
-                    step={0.5}
-                    formatValue={(value) => `${value.toFixed(1)} пкс`}
-                    onChange={(pointSize) => setDisplayDraft((current) => ({ ...current, pointSize }))}
-                  />
-                  <ControlRow label="Атрибут цвета">
-                    <Select
-                      variant="split"
-                      label="Атрибут цвета"
-                      value={displayDraft.colorMode}
-                      options={colorModeOptions}
-                      onChange={(colorMode) => setDisplayDraft((current) => ({ ...current, colorMode }))}
+                  <div
+                    className="scene-settings-commit-field"
+                    onPointerUp={flushDisplaySettings}
+                    onKeyUp={flushDisplaySettings}
+                    onBlur={flushDisplaySettings}
+                  >
+                    <RangeControl
+                      label="Размер точки"
+                      value={displayDraft.pointSize}
+                      min={0.5}
+                      max={12}
+                      step={0.5}
+                      formatValue={(value) => `${value.toFixed(1)} пкс`}
+                      onChange={(pointSize) => stageDisplayPatch({ pointSize })}
                     />
-                  </ControlRow>
-                  <ControlRow label="Палитра">
-                    <Select
-                      variant="split"
-                      label="Палитра"
-                      value={displayDraft.palette}
-                      options={paletteOptions}
-                      onChange={(palette) => setDisplayDraft((current) => ({ ...current, palette }))}
-                    />
-                  </ControlRow>
-                  {displayDraft.palette === "custom" ? (
-                    <ControlRow label="Цвет точек">
-                      <ColorField
-                        label="Цвет точек"
-                        value={displayDraft.customColor}
-                        onChange={(customColor) => setDisplayDraft((current) => ({ ...current, customColor }))}
+                  </div>
+                  <div className="scene-settings-commit-field" onBlur={flushDisplaySettings}>
+                    <ControlRow label="Атрибут цвета">
+                      <Select
+                        variant="split"
+                        label="Атрибут цвета"
+                        value={displayDraft.colorMode}
+                        options={colorModeOptions}
+                        disabled={replayActive}
+                        onChange={(colorMode) => stageDisplayPatch({ colorMode })}
                       />
                     </ControlRow>
+                  </div>
+                  <div className="scene-settings-commit-field" onBlur={flushDisplaySettings}>
+                    <ControlRow label="Палитра">
+                      <Select
+                        variant="split"
+                        label="Палитра"
+                        value={displayDraft.palette}
+                        options={displayPaletteOptions}
+                        onChange={(palette) => stageDisplayPatch({ palette })}
+                      />
+                    </ControlRow>
+                  </div>
+                  {displayDraft.palette === "custom" ? (
+                    <div
+                      className="scene-settings-commit-field"
+                      onPointerUp={flushDisplaySettings}
+                      onKeyUp={flushDisplaySettings}
+                      onBlur={flushDisplaySettings}
+                    >
+                      <ControlRow label="Цвет точек">
+                        <ColorField
+                          label="Цвет точек"
+                          value={displayDraft.customColor}
+                          onChange={(customColor) => stageDisplayPatch({ customColor })}
+                        />
+                      </ControlRow>
+                    </div>
+                  ) : null}
+                  {replayActive ? (
+                    <p className="scene-window-note">
+                      В архиве градиентные цвета уже записаны в RRD. Без переэкспорта
+                      можно вернуть цвет записи или назначить один свой цвет.
+                    </p>
                   ) : null}
                 </div>
               ),
@@ -601,21 +910,28 @@ export default function App() {
               description: "История облака и траектория",
               content: (
                 <div className="inspector-control-stack">
-                  <RangeControl
-                    label="Окно накопления"
-                    value={displayDraft.accumulationSeconds}
-                    min={0}
-                    max={120}
-                    step={1}
-                    formatValue={(value) => (value === 0 ? "Только кадр" : `${value} с`)}
-                    onChange={(accumulationSeconds) => setDisplayDraft((current) => ({ ...current, accumulationSeconds }))}
-                  />
+                  <div
+                    className="scene-settings-commit-field"
+                    onPointerUp={flushDisplaySettings}
+                    onKeyUp={flushDisplaySettings}
+                    onBlur={flushDisplaySettings}
+                  >
+                    <RangeControl
+                      label="Окно накопления"
+                      value={displayDraft.accumulationSeconds}
+                      min={0}
+                      max={120}
+                      step={1}
+                      formatValue={(value) => (value === 0 ? "Только кадр" : `${value} с`)}
+                      onChange={(accumulationSeconds) => stageDisplayPatch({ accumulationSeconds })}
+                    />
+                  </div>
                   <div className="nodedc-field">
                     <span className="nodedc-field__description">Линия пути устройства в координатах сцены</span>
                     <Checker
                       checked={displayDraft.showTrajectory}
                       label="Показывать траекторию"
-                      onChange={(showTrajectory) => setDisplayDraft((current) => ({ ...current, showTrajectory }))}
+                      onChange={(showTrajectory) => commitDisplayPatch({ showTrajectory })}
                     />
                   </div>
                 </div>
@@ -627,7 +943,7 @@ export default function App() {
               description: "Сетка, подписи и камеры",
               content: (
                 <div className="inspector-control-stack">
-                  <Checker checked={displayDraft.showGrid} label="Сетка и оси" onChange={(showGrid) => setDisplayDraft((current) => ({ ...current, showGrid }))} />
+                  <Checker checked={displayDraft.showGrid} label="Сетка и оси" onChange={(showGrid) => commitDisplayPatch({ showGrid })} />
                   <div className="nodedc-field">
                     <span className="nodedc-field__description">Появятся после подключения семантических сущностей</span>
                     <Checker checked={false} disabled label="Подписи сущностей" onChange={() => undefined} />
@@ -726,59 +1042,6 @@ export default function App() {
         />
       </Window>
 
-      <Window
-        open={layoutWindowOpen}
-        title="Компоновка рабочей области"
-        subtitle="КОМПОНОВКА / ЧЕРНОВИК"
-        size="sm"
-        placement="end"
-        draggable
-        closeOnBackdrop={false}
-        closeOnEscape={false}
-        lockBodyScroll={false}
-        trapFocus={false}
-        className="scene-tool-window scene-tool-window--layout"
-        data-scene-window="layout"
-        data-scene-active={activeSceneWindow === "layout" ? "true" : undefined}
-        onPointerDown={() => activateSceneWindow("layout")}
-        onClose={() => closeSceneWindow("layout")}
-        footer={
-          <WindowFooterActions>
-            <Button onClick={() => closeSceneWindow("layout")}>Закрыть</Button>
-            <Button
-              variant="primary"
-              shape="pill"
-              disabled={!layoutName.trim()}
-              onClick={() => setLayoutDraftSaved(true)}
-            >
-              Зафиксировать черновик
-            </Button>
-          </WindowFooterActions>
-        }
-      >
-        <div className="modal-stack">
-          <TextField
-            label="Название компоновки"
-            value={layoutName}
-            onChange={(event) => {
-              setLayoutName(event.target.value);
-              setLayoutDraftSaved(false);
-            }}
-            placeholder="Название профиля"
-          />
-          <div className="modal-contract-note" data-tone={layoutDraftSaved ? "success" : "warning"}>
-            <Icon name={layoutDraftSaved ? "check" : "save"} />
-            <div>
-              <strong>{layoutDraftSaved ? "Черновик зафиксирован в текущем сеансе" : "Экспорт RBL ещё не подключён"}</strong>
-              <p>
-                {layoutDraftSaved
-                  ? "Это состояние интерфейса без записи на диск. Будущий адаптер сохранит профиль Rerun рядом с кодом."
-                  : "Окно и контракт сохранения готовы; запись файла не имитируется."}
-              </p>
-            </div>
-          </div>
-        </div>
-      </Window>
     </>
   );
 }
diff --git a/apps/control-station/src/components/FloatingObservationWindow.tsx b/apps/control-station/src/components/FloatingObservationWindow.tsx
index 2209a2a..aa19187 100644
--- a/apps/control-station/src/components/FloatingObservationWindow.tsx
+++ b/apps/control-station/src/components/FloatingObservationWindow.tsx
@@ -4,6 +4,11 @@ import { WorkspaceWindow } from "@nodedc/ui-react";
 import type { ObservationWindowRect } from "../core/observation/useObservationLayout";
 import type { ObservationSourceDescriptor } from "../core/runtime/contracts";
 import { ObservationMedia, observationSourceStatusLabel } from "./ObservationSources";
+import type { RecordedObservationPlayback } from "./RecordedFmp4Player";
+import type {
+  RecordedAdmissionPhase,
+  RecordedCameraAdmissionState,
+} from "../core/observation/recordedSessionAdmission";
 
 const WINDOW_WIDTH = 336;
 const WINDOW_HEIGHT = 210;
@@ -11,6 +16,18 @@ const WINDOW_GAP = 16;
 const WINDOW_INSET = 18;
 const TIMELINE_CLEARANCE = 64;
 
+type ClosestTarget = { closest: (selectors: string) => unknown };
+
+export function shouldCaptureWorkspacePointer(
+  button: number,
+  target: ClosestTarget | null,
+): boolean {
+  if (button !== 0 || !target) return false;
+  if (target.closest(".nodedc-workspace-window__resize")) return true;
+  if (!target.closest(".nodedc-workspace-window__head")) return false;
+  return !target.closest("button, input, select, textarea, a");
+}
+
 export function initialObservationWindowRect(
   index: number,
   count = 1,
@@ -59,6 +76,11 @@ export function FloatingObservationWindow({
   onMaximizedChange,
   onActivate,
   onClose,
+  playback,
+  prepareRecorded,
+  recordedSessionGate,
+  recordedAdmissionKey,
+  onRecordedAdmissionChange,
 }: {
   source: ObservationSourceDescriptor;
   index: number;
@@ -71,6 +93,14 @@ export function FloatingObservationWindow({
   onMaximizedChange: (maximized: boolean) => void;
   onActivate: () => void;
   onClose: () => void;
+  playback?: RecordedObservationPlayback | null;
+  prepareRecorded?: boolean;
+  recordedSessionGate?: RecordedAdmissionPhase;
+  recordedAdmissionKey?: string | null;
+  onRecordedAdmissionChange?: (
+    sourceId: string,
+    state: RecordedCameraAdmissionState,
+  ) => void;
 }) {
   const [bounds, setBounds] = useState<{ width: number; height: number } | null>(null);
 
@@ -124,13 +154,29 @@ export function FloatingObservationWindow({
       active={active}
       zIndex={maximized ? 15 : active ? 9 : 7}
       className="floating-observation-window"
+      onPointerDownCapture={(event) => {
+        if (!shouldCaptureWorkspacePointer(event.button, event.target as HTMLElement)) return;
+        try {
+          event.currentTarget.setPointerCapture(event.pointerId);
+        } catch {
+          // Pointer capture can fail if the browser ended the pointer between
+          // dispatch and capture. The donor's window listeners remain fallback.
+        }
+      }}
       closeLabel={`Закрыть ${source.label}`}
       maximizeLabel={`Развернуть ${source.label}`}
       restoreLabel={`Восстановить ${source.label}`}
       moveLabel={`Переместить ${source.label}`}
       resizeLabel={`Изменить размер ${source.label}`}
     >
-      <ObservationMedia source={source} />
+      <ObservationMedia
+        source={source}
+        playback={playback}
+        prepareRecorded={prepareRecorded}
+        recordedSessionGate={recordedSessionGate}
+        recordedAdmissionKey={recordedAdmissionKey}
+        onRecordedAdmissionChange={onRecordedAdmissionChange}
+      />
     </WorkspaceWindow>
   );
 }
diff --git a/apps/control-station/src/components/ObservationSessionSelect.tsx b/apps/control-station/src/components/ObservationSessionSelect.tsx
new file mode 100644
index 0000000..dad78f9
--- /dev/null
+++ b/apps/control-station/src/components/ObservationSessionSelect.tsx
@@ -0,0 +1,239 @@
+import { Dropdown, Icon } from "@nodedc/ui-react";
+
+import {
+  type ObservationSessionReplayLaunch,
+  type ObservationSessionSummary,
+} from "../core/observation/sessionArchive";
+import { useObservationSessions } from "../core/observation/useObservationSessions";
+import type {
+  ObservationPreparationPhase,
+  ObservationReplayOutcome,
+} from "../core/observation/useObservationSessions";
+import "../styles/observation-sessions.css";
+
+type SessionVisualState = "ready" | "processing" | "error";
+
+export function observationSessionVisualState(
+  session: ObservationSessionSummary,
+  { pending = false, failed = false }: { pending?: boolean; failed?: boolean } = {},
+): SessionVisualState {
+  if (failed) return "error";
+  if (pending) return "processing";
+  if (session.preparation !== null) {
+    if (["queued", "validating", "exporting", "finalizing"].includes(
+      session.preparation.state,
+    )) return "processing";
+    if (session.preparation.state === "ready" && session.replayable) return "ready";
+    return "error";
+  }
+  return session.status === "recording" ? "processing" : "error";
+}
+
+export function observationSessionVisualLabel(state: SessionVisualState): string {
+  if (state === "ready") return "Готово";
+  if (state === "processing") return "Обработка";
+  return "Ошибка";
+}
+
+const modalityLabel: Record<string, string> = {
+  "point-cloud": "облако точек",
+  pose: "траектория",
+  trajectory: "траектория",
+  video: "видео",
+  image: "изображения",
+  depth: "глубина",
+  telemetry: "телеметрия",
+};
+
+const preparationLabel: Record<ObservationPreparationPhase, string> = {
+  requesting: "Запрашиваем подготовку",
+  queued: "В очереди",
+  validating: "Проверяем запись",
+  exporting: "Готовим облако точек",
+  finalizing: "Завершаем подготовку",
+  failed: "Подготовка не выполнена",
+  cancelled: "Подготовка отменена",
+};
+
+function progressCopy(
+  phase: ObservationPreparationPhase,
+  progress: number | null,
+): string {
+  const label = preparationLabel[phase];
+  return progress === null ? label : `${label} · ${Math.round(progress * 100)}%`;
+}
+
+function formatStartedAt(value: string): string {
+  return new Intl.DateTimeFormat("ru-RU", {
+    day: "2-digit",
+    month: "2-digit",
+    year: "numeric",
+    hour: "2-digit",
+    minute: "2-digit",
+  }).format(new Date(value));
+}
+
+function formatDuration(seconds: number): string {
+  const totalSeconds = Math.max(0, Math.round(seconds));
+  const hours = Math.floor(totalSeconds / 3_600);
+  const minutes = Math.floor((totalSeconds % 3_600) / 60);
+  const remainingSeconds = totalSeconds % 60;
+  return hours > 0
+    ? `${hours}:${String(minutes).padStart(2, "0")}:${String(remainingSeconds).padStart(2, "0")}`
+    : `${minutes}:${String(remainingSeconds).padStart(2, "0")}`;
+}
+
+function sessionDescription(session: ObservationSessionSummary): string {
+  const modalities = session.modalities.length
+    ? session.modalities.map((value) => modalityLabel[value] ?? value).join(" · ")
+    : "каналы не зафиксированы";
+  return `${formatStartedAt(session.startedAtUtc)} · ${formatDuration(session.durationSeconds)} · ${modalities}`;
+}
+
+export function ObservationSessionSelect({
+  limit = 3,
+  disabled = false,
+  onReplayBegin,
+  onReplayAccepted,
+  onReplaySettled,
+}: {
+  limit?: number;
+  disabled?: boolean;
+  onReplayBegin?: (
+    session: ObservationSessionSummary,
+    launch: ObservationSessionReplayLaunch,
+  ) => void | Promise<void>;
+  onReplayAccepted?: (
+    session: ObservationSessionSummary,
+    launch: ObservationSessionReplayLaunch,
+  ) => void | Promise<void>;
+  onReplaySettled?: (
+    session: ObservationSessionSummary,
+    outcome: ObservationReplayOutcome,
+  ) => void | Promise<void>;
+}) {
+  const sessions = useObservationSessions({
+    limit,
+    onReplayBegin,
+    onReplayAccepted,
+    onReplaySettled,
+  });
+  const triggerCopy = sessions.replayProgress
+    ? progressCopy(sessions.replayProgress.phase, sessions.replayProgress.progress)
+    : sessions.state === "loading"
+      ? "Загружаем сессии…"
+      : "Сохранённые сессии";
+
+  return (
+    <Dropdown
+      className="observation-session-select"
+      placement="bottom-end"
+      width={390}
+      offset={10}
+      disabled={disabled}
+      surfaceRole="dialog"
+      surfaceClassName="observation-session-menu"
+      trigger={({ open, toggle, setAnchorRef, setTriggerRef, surfaceId }) => (
+        <button
+          ref={(node) => {
+            setAnchorRef(node);
+            setTriggerRef(node);
+          }}
+          type="button"
+          className="observation-session-select__trigger"
+          data-active={open ? "true" : undefined}
+          aria-label="Открыть сохранённые сессии наблюдения"
+          aria-haspopup="dialog"
+          aria-expanded={open}
+          aria-controls={surfaceId}
+          disabled={disabled}
+          onClick={toggle}
+        >
+          <Icon name="database" size={15} />
+          <span>{triggerCopy}</span>
+          {sessions.state === "ready" ? <small>{sessions.items.length}</small> : null}
+          <Icon name="chevron-down" size={14} />
+        </button>
+      )}
+    >
+      {({ close }) => (
+        <div className="observation-session-menu__content">
+          <header className="observation-session-menu__head">
+            <div>
+              <span className="section-eyebrow">ИСТОРИЯ НАБЛЮДЕНИЯ</span>
+              <strong>Сохранённые сессии</strong>
+            </div>
+            <button
+              type="button"
+              aria-label="Обновить каталог сессий"
+              disabled={sessions.state === "loading"}
+              onClick={() => void sessions.refresh()}
+            >
+              <Icon name="refresh" size={14} />
+            </button>
+          </header>
+
+          {sessions.items.length > 0 ? (
+            <div className="observation-session-menu__list">
+              {sessions.items.map((session) => {
+                const pending = sessions.replayingSessionId === session.id;
+                const failed = sessions.failedSessionId === session.id;
+                const visualState = observationSessionVisualState(session, { pending, failed });
+                return (
+                  <button
+                    key={session.id}
+                    type="button"
+                    className="nodedc-dropdown-option observation-session-option"
+                    disabled={pending || !session.replayable}
+                    onClick={() => {
+                      void sessions.replay(session.id).then((accepted) => {
+                        if (accepted) close();
+                      });
+                    }}
+                  >
+                    <span className="nodedc-dropdown-option__icon">
+                      <i data-session-visual-state={visualState} aria-hidden="true" />
+                    </span>
+                    <span className="nodedc-dropdown-option__body">
+                      <span className="nodedc-dropdown-option__label">{session.label}</span>
+                      <span className="nodedc-dropdown-option__description">
+                        {sessionDescription(session)}
+                      </span>
+                    </span>
+                    <span className="observation-session-option__state">
+                      {observationSessionVisualLabel(visualState)}
+                    </span>
+                  </button>
+                );
+              })}
+            </div>
+          ) : sessions.state === "loading" ? (
+            <div className="observation-session-menu__empty" role="status">
+              <span className="busy-indicator" aria-hidden="true" />
+              <strong>Читаем каталог</strong>
+            </div>
+          ) : (
+            <div className="observation-session-menu__empty">
+              <Icon name={sessions.error ? "alert" : "database"} size={18} />
+              <strong>{sessions.error ? "Каталог недоступен" : "Сессий пока нет"}</strong>
+              <span>{sessions.error ?? "Завершённые записи появятся здесь автоматически."}</span>
+            </div>
+          )}
+
+          {sessions.error && sessions.items.length > 0 ? (
+            <footer className="observation-session-menu__error" role="alert">
+              <Icon name="alert" size={13} />
+              <span>{sessions.error}</span>
+              {sessions.failedSessionId ? (
+                <button type="button" onClick={() => void sessions.retry()}>
+                  Повторить
+                </button>
+              ) : null}
+            </footer>
+          ) : null}
+
+        </div>
+      )}
+    </Dropdown>
+  );
+}
diff --git a/apps/control-station/src/components/ObservationSources.tsx b/apps/control-station/src/components/ObservationSources.tsx
index 8ff5b9b..89a29eb 100644
--- a/apps/control-station/src/components/ObservationSources.tsx
+++ b/apps/control-station/src/components/ObservationSources.tsx
@@ -6,6 +6,14 @@ import type {
   ObservationSourceModality,
 } from "../core/runtime/contracts";
 import { MseFmp4WebSocketPlayer } from "./MseFmp4WebSocketPlayer";
+import {
+  RecordedFmp4Player,
+  type RecordedObservationPlayback,
+} from "./RecordedFmp4Player";
+import type {
+  RecordedAdmissionPhase,
+  RecordedCameraAdmissionState,
+} from "../core/observation/recordedSessionAdmission";
 
 const sourceIcon: Record<ObservationSourceModality, IconName> = {
   "point-cloud": "globe",
@@ -29,7 +37,24 @@ export function observationSourceStatusLabel(source: ObservationSourceDescriptor
   return availabilityCopy[source.availability];
 }
 
-export function ObservationMedia({ source }: { source: ObservationSourceDescriptor }) {
+export function ObservationMedia({
+  source,
+  playback,
+  prepareRecorded = true,
+  recordedSessionGate = "ready",
+  recordedAdmissionKey = null,
+  onRecordedAdmissionChange,
+}: {
+  source: ObservationSourceDescriptor;
+  playback?: RecordedObservationPlayback | null;
+  prepareRecorded?: boolean;
+  recordedSessionGate?: RecordedAdmissionPhase;
+  recordedAdmissionKey?: string | null;
+  onRecordedAdmissionChange?: (
+    sourceId: string,
+    state: RecordedCameraAdmissionState,
+  ) => void;
+}) {
   const sourceSelected = source.activation ? source.activation.selected : true;
   const deliveryActive = Boolean(source.delivery && sourceSelected);
 
@@ -41,6 +66,32 @@ export function ObservationMedia({ source }: { source: ObservationSourceDescript
     return <MseFmp4WebSocketPlayer delivery={source.delivery} label={source.label} />;
   }
 
+  if (
+    deliveryActive &&
+    source.delivery?.kind === "recorded-fmp4-manifest" &&
+    source.modality === "video"
+  ) {
+    if (!prepareRecorded) {
+      return (
+        <div className="observation-media__empty" role="status">
+          <span className="busy-indicator" aria-hidden="true" />
+          <strong>Ожидает подготовки</strong>
+          <span>Канал будет проверен последовательно в рамках атомарной сессии.</span>
+        </div>
+      );
+    }
+    return (
+      <RecordedFmp4Player
+        source={source}
+        playback={playback}
+        prepare
+        sessionGate={recordedSessionGate}
+        admissionKey={recordedAdmissionKey}
+        onAdmissionChange={(state) => onRecordedAdmissionChange?.(source.id, state)}
+      />
+    );
+  }
+
   if (deliveryActive && source.delivery?.kind === "video-url" && source.modality === "video") {
     return (
       <video
@@ -193,7 +244,8 @@ export function ObservationSourcePicker({
         </div>
       )}
       <footer className="observation-source-menu__foot">
-        Каналы приходят из активного device-плагина; сцена не знает модель оборудования.
+        Каналы приходят из активного контура или выбранной сохранённой сессии; сцена не знает
+        модель оборудования.
       </footer>
     </Dropdown>
   );
diff --git a/apps/control-station/src/components/ObservationTimeline.tsx b/apps/control-station/src/components/ObservationTimeline.tsx
index 41431e3..a030d87 100644
--- a/apps/control-station/src/components/ObservationTimeline.tsx
+++ b/apps/control-station/src/components/ObservationTimeline.tsx
@@ -8,6 +8,15 @@ export function ObservationTimeline({
   mode = "live-only",
   seekable = false,
   synchronization = "host-arrival-best-effort",
+  rangeNs = null,
+  currentNs = null,
+  playing = false,
+  onSeek,
+  onPlayingChange,
+  onJumpToEnd,
+  accumulationSeconds,
+  onAccumulationChange,
+  onAccumulationCommit,
   className = "",
 }: {
   active: boolean;
@@ -15,38 +24,151 @@ export function ObservationTimeline({
   mode?: ObservationTimelineMode;
   seekable?: boolean;
   synchronization?: "host-arrival-best-effort" | "shared-clock" | "frame-accurate";
+  rangeNs?: { min: number; max: number } | null;
+  currentNs?: number | null;
+  playing?: boolean;
+  onSeek?: (timeNs: number) => void;
+  onPlayingChange?: (playing: boolean) => void;
+  onJumpToEnd?: () => void;
+  accumulationSeconds?: number;
+  onAccumulationChange?: (value: number) => void;
+  onAccumulationCommit?: () => void;
   className?: string;
 }) {
-  const buffered = seekable && (mode === "buffered" || mode === "recorded");
+  const playbackRange = normalizeTimelineRange(rangeNs);
+  const buffered = Boolean(
+    seekable &&
+    (mode === "buffered" || mode === "recorded") &&
+    playbackRange,
+  );
+  const elapsedSeconds = playbackRange
+    ? timelineOffsetSeconds(playbackRange, currentNs ?? playbackRange.min)
+    : 0;
+  const durationSeconds = playbackRange
+    ? Math.max(0, (playbackRange.max - playbackRange.min) / 1_000_000_000)
+    : 0;
   const synchronizationLabel = {
     "host-arrival-best-effort": "Синхронизация по приходу",
     "shared-clock": "Общие часы",
     "frame-accurate": "Покадровая синхронизация",
   }[synchronization];
+  const accumulationValue = accumulationSeconds === undefined
+    ? null
+    : normalizeAccumulationSeconds(accumulationSeconds);
   return (
     <div
       className={`observation-timeline ${className}`.trim()}
       data-active={active ? "true" : undefined}
       data-mode={mode}
+      data-accumulation={accumulationValue !== null ? "true" : undefined}
     >
-      <Button size="compact" variant="ghost" disabled aria-label="Перейти к началу">
-        <Icon name="chevron-left" />
-      </Button>
-      <Button size="compact" variant="secondary" disabled>
-        {buffered ? "Воспроизвести" : "Только эфир"}
-      </Button>
-      <div className="observation-timeline__track" data-disabled={!buffered ? "true" : undefined}>
-        <span style={{ width: active ? "100%" : "0%" }} />
+      {accumulationValue !== null ? (
+        <div className="observation-timeline__accumulation">
+          <span>Накопление</span>
+          <input
+            className="observation-timeline__track"
+            type="range"
+            min={0}
+            max={120}
+            step={1}
+            value={accumulationValue}
+            aria-label="Окно накопления облака точек"
+            aria-valuetext={formatAccumulationDuration(accumulationValue)}
+            onChange={(event) =>
+              onAccumulationChange?.(normalizeAccumulationSeconds(Number(event.target.value)))}
+            onPointerUp={onAccumulationCommit}
+            onTouchEnd={onAccumulationCommit}
+            onKeyUp={onAccumulationCommit}
+            onBlur={onAccumulationCommit}
+          />
+          <code>{formatAccumulationDuration(accumulationValue)}</code>
+        </div>
+      ) : null}
+      <div className="observation-timeline__playback">
+        <Button
+          size="compact"
+          variant="ghost"
+          disabled={!buffered || !onSeek}
+          aria-label="Перейти к началу"
+          onClick={() => playbackRange && onSeek?.(playbackRange.min)}
+        >
+          <Icon name="chevron-left" />
+        </Button>
+        <Button
+          size="compact"
+          variant="secondary"
+          disabled={!buffered || !onPlayingChange}
+          onClick={() => onPlayingChange?.(!playing)}
+        >
+          {buffered ? (playing ? "Пауза" : "Воспроизвести") : "Только эфир"}
+        </Button>
+        <input
+          className="observation-timeline__track"
+          type="range"
+          min={0}
+          max={Math.max(durationSeconds, 0.001)}
+          step={0.01}
+          value={Math.min(elapsedSeconds, durationSeconds)}
+          disabled={!buffered || !onSeek}
+          aria-label="Позиция воспроизведения"
+          onChange={(event) => {
+            if (!playbackRange) return;
+            onSeek?.(playbackRange.min + Number(event.target.value) * 1_000_000_000);
+          }}
+        />
+        <div className="observation-timeline__meta">
+          <code>
+            {buffered
+              ? `${formatTimelineDuration(elapsedSeconds)} / ${formatTimelineDuration(durationSeconds)}`
+              : active ? "LIVE" : "—:—:—.———"}
+          </code>
+          <small>
+            {buffered ? `${sourceCount} каналов` : `${synchronizationLabel} · буфер не включён`}
+          </small>
+        </div>
+        <button
+          type="button"
+          className="observation-timeline__follow"
+          data-active={!buffered && active ? "true" : undefined}
+          disabled={buffered ? !onJumpToEnd : true}
+          onClick={onJumpToEnd}
+        >
+          {buffered ? "К КОНЦУ" : "ЭФИР"}
+        </button>
       </div>
-      <div className="observation-timeline__meta">
-        <code>{active ? "LIVE" : "—:—:—.———"}</code>
-        <small>
-          {buffered ? `${sourceCount} каналов` : `${synchronizationLabel} · буфер не включён`}
-        </small>
-      </div>
-      <span className="observation-timeline__follow" data-active={active ? "true" : undefined}>
-        ЭФИР
-      </span>
     </div>
   );
 }
+
+export function normalizeAccumulationSeconds(value: number): number {
+  if (!Number.isFinite(value)) return 0;
+  return Math.min(120, Math.max(0, Math.round(value)));
+}
+
+export function formatAccumulationDuration(value: number): string {
+  const seconds = normalizeAccumulationSeconds(value);
+  return seconds === 0 ? "Кадр" : `${seconds} с`;
+}
+
+export function normalizeTimelineRange(
+  range: { min: number; max: number } | null | undefined,
+): { min: number; max: number } | null {
+  if (!range || !Number.isFinite(range.min) || !Number.isFinite(range.max)) return null;
+  if (range.max <= range.min) return null;
+  return range;
+}
+
+export function timelineOffsetSeconds(
+  range: { min: number; max: number },
+  currentNs: number,
+): number {
+  const clamped = Math.min(Math.max(currentNs, range.min), range.max);
+  return Math.max(0, (clamped - range.min) / 1_000_000_000);
+}
+
+export function formatTimelineDuration(seconds: number): string {
+  if (!Number.isFinite(seconds) || seconds < 0) return "00:00.000";
+  const wholeMinutes = Math.floor(seconds / 60);
+  const remaining = seconds - wholeMinutes * 60;
+  return `${String(wholeMinutes).padStart(2, "0")}:${remaining.toFixed(3).padStart(6, "0")}`;
+}
diff --git a/apps/control-station/src/components/RecordedFmp4Player.tsx b/apps/control-station/src/components/RecordedFmp4Player.tsx
new file mode 100644
index 0000000..8192238
--- /dev/null
+++ b/apps/control-station/src/components/RecordedFmp4Player.tsx
@@ -0,0 +1,735 @@
+import { sha256 } from "@noble/hashes/sha2.js";
+import { bytesToHex } from "@noble/hashes/utils.js";
+import { useEffect, useMemo, useRef, useState } from "react";
+
+import {
+  fetchObservationRecordedMediaManifest,
+  ObservationSessionContractError,
+  type ObservationRecordedMediaEpoch,
+  type ObservationRecordedMediaManifest,
+  type ObservationRecordedMediaSource,
+  type ObservationSessionFetch,
+} from "../core/observation/sessionArchive";
+import {
+  MAX_RECORDED_MEDIA_SOURCE_BYTES,
+  type RecordedAdmissionPhase,
+  type RecordedCameraAdmissionState,
+} from "../core/observation/recordedSessionAdmission";
+import type { ObservationSourceDescriptor } from "../core/runtime/contracts";
+
+export interface RecordedObservationPlayback {
+  currentSeconds: number;
+  playing: boolean;
+}
+
+export interface RecordedMediaLoadProgress {
+  loadedBytes: number;
+  totalBytes: number;
+  loadedParts: number;
+  totalParts: number;
+}
+
+interface VerifiedRecordedMediaEpoch {
+  descriptor: ObservationRecordedMediaEpoch;
+  readonly init: ArrayBuffer;
+  readonly segments: readonly ArrayBuffer[];
+}
+
+export interface VerifiedRecordedMediaArchive {
+  manifest: ObservationRecordedMediaManifest;
+  epochs: readonly VerifiedRecordedMediaEpoch[];
+  byteLength: number;
+}
+
+interface RecordedMediaBinaryDescriptor {
+  url: string;
+  byteLength: number;
+  sha256: string;
+  accept: string;
+}
+
+export type RecordedMediaPresentationState = "loading" | "ready" | "waiting" | "error";
+
+export const RECORDED_MEDIA_DURATION_TOLERANCE_SECONDS = 1;
+let recordedMediaWorkerGeneration = 0;
+
+export function recordedMediaPresentationState(
+  state: "loading" | "ready" | "error",
+  readyGeneration: string | null,
+  selectedGeneration: string | null,
+  waitingForEpoch: boolean,
+  sessionGate: RecordedAdmissionPhase = "ready",
+): RecordedMediaPresentationState {
+  if (state === "error" || sessionGate === "error") return "error";
+  if (sessionGate !== "ready") return "loading";
+  if (waitingForEpoch) return "waiting";
+  return state === "ready" &&
+    selectedGeneration !== null &&
+    readyGeneration === selectedGeneration
+    ? "ready"
+    : "loading";
+}
+
+export function selectRecordedMediaEpoch(
+  epochs: readonly ObservationRecordedMediaEpoch[],
+  currentSeconds: number,
+): ObservationRecordedMediaEpoch | null {
+  if (!epochs.length || !Number.isFinite(currentSeconds)) return null;
+  let selected: ObservationRecordedMediaEpoch | null = null;
+  for (const epoch of epochs) {
+    if (epoch.timelineStartSeconds > currentSeconds) break;
+    selected = epoch;
+  }
+  return selected && currentSeconds <= selected.timelineEndSeconds ? selected : null;
+}
+
+export function recordedMediaSeekableCoverage(
+  durationSeconds: number,
+  seekableEndSeconds: number,
+  declaredDurationSeconds: number,
+  toleranceSeconds = RECORDED_MEDIA_DURATION_TOLERANCE_SECONDS,
+  seekableStartSeconds = 0,
+): boolean {
+  return (
+    Number.isFinite(durationSeconds) &&
+    Number.isFinite(seekableEndSeconds) &&
+    Number.isFinite(declaredDurationSeconds) &&
+    Number.isFinite(seekableStartSeconds) &&
+    declaredDurationSeconds > 0 &&
+    toleranceSeconds >= 0 &&
+    durationSeconds + toleranceSeconds >= declaredDurationSeconds &&
+    seekableStartSeconds <= toleranceSeconds &&
+    seekableStartSeconds >= -toleranceSeconds &&
+    seekableEndSeconds + toleranceSeconds >= declaredDurationSeconds
+  );
+}
+
+export function recordedMediaLocalTime(
+  epochStartSeconds: number,
+  currentSeconds: number,
+  durationSeconds = Number.POSITIVE_INFINITY,
+): number {
+  if (!Number.isFinite(epochStartSeconds) || !Number.isFinite(currentSeconds)) return 0;
+  const local = Math.max(0, currentSeconds - epochStartSeconds);
+  return Number.isFinite(durationSeconds)
+    ? Math.min(local, Math.max(0, durationSeconds))
+    : local;
+}
+
+function sourceContract(source: ObservationSourceDescriptor): ObservationRecordedMediaSource | null {
+  const delivery = source.delivery;
+  if (!delivery || delivery.kind !== "recorded-fmp4-manifest") return null;
+  return {
+    id: source.id,
+    label: source.label,
+    modality: "video",
+    manifestUrl: delivery.url,
+    manifestGenerationSha256: delivery.manifestGenerationSha256,
+    byteLength: delivery.byteLength,
+    mediaType: delivery.mediaType,
+    timelineStartSeconds: delivery.timelineStartSeconds,
+    timelineEndSeconds: delivery.timelineEndSeconds,
+    seekable: true,
+    synchronization: "host-arrival-best-effort",
+  };
+}
+
+function expectedPayloadEtag(digest: string): string {
+  return `"sha256:${digest}"`;
+}
+
+export async function fetchVerifiedRecordedMediaBytes(
+  descriptor: RecordedMediaBinaryDescriptor,
+  {
+    signal,
+    fetcher = globalThis.fetch,
+  }: { signal?: AbortSignal; fetcher?: ObservationSessionFetch } = {},
+): Promise<ArrayBuffer> {
+  let response: Response;
+  try {
+    response = await fetcher(descriptor.url, {
+      method: "GET",
+      headers: {
+        Accept: descriptor.accept,
+        "If-Match": expectedPayloadEtag(descriptor.sha256),
+      },
+      signal,
+    });
+  } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") throw error;
+    throw new ObservationSessionContractError(
+      "Не удалось загрузить канонический фрагмент записанного видео.",
+    );
+  }
+  if (!response.ok || response.status !== 200) {
+    throw new ObservationSessionContractError(
+      `Фрагмент записанного видео вернул HTTP ${response.status}.`,
+    );
+  }
+  if (response.headers.get("ETag") !== expectedPayloadEtag(descriptor.sha256)) {
+    throw new ObservationSessionContractError(
+      "Фрагмент записанного видео не соответствует immutable manifest.",
+    );
+  }
+  const contentLength = response.headers.get("Content-Length");
+  if (
+    contentLength === null ||
+    !/^[1-9][0-9]*$/.test(contentLength) ||
+    Number(contentLength) !== descriptor.byteLength
+  ) {
+    throw new ObservationSessionContractError(
+      "Длина фрагмента записанного видео не соответствует immutable manifest.",
+    );
+  }
+  const payload = await response.arrayBuffer();
+  if (payload.byteLength !== descriptor.byteLength) {
+    throw new ObservationSessionContractError(
+      "Фрагмент записанного видео был усечён во время передачи.",
+    );
+  }
+  const digest = bytesToHex(sha256(new Uint8Array(payload)));
+  if (digest !== descriptor.sha256) {
+    throw new ObservationSessionContractError(
+      "SHA-256 фрагмента записанного видео не совпадает с immutable manifest.",
+    );
+  }
+  return payload;
+}
+
+function manifestIdentity(manifest: ObservationRecordedMediaManifest): string {
+  return JSON.stringify(manifest);
+}
+
+export async function fetchVerifiedRecordedMediaArchive(
+  source: ObservationRecordedMediaSource,
+  {
+    signal,
+    fetcher = globalThis.fetch,
+    onProgress,
+  }: {
+    signal?: AbortSignal;
+    fetcher?: ObservationSessionFetch;
+    onProgress?: (progress: RecordedMediaLoadProgress) => void;
+  } = {},
+): Promise<VerifiedRecordedMediaArchive> {
+  const manifest = await fetchObservationRecordedMediaManifest(source, {
+    signal,
+    fetcher,
+    expectedGenerationSha256: source.manifestGenerationSha256,
+  });
+  const totalBytes = manifest.epochs.reduce(
+    (archiveTotal, epoch) => archiveTotal + epoch.initByteLength + epoch.segments.reduce(
+      (epochTotal, segment) => epochTotal + segment.byteLength,
+      0,
+    ),
+    0,
+  );
+  const totalParts = manifest.epochs.reduce(
+    (total, epoch) => total + 1 + epoch.segments.length,
+    0,
+  );
+  if (
+    totalBytes < 1 ||
+    totalBytes > MAX_RECORDED_MEDIA_SOURCE_BYTES ||
+    totalBytes !== manifest.byteLength ||
+    totalBytes !== source.byteLength
+  ) {
+    throw new ObservationSessionContractError(
+      "Размер записанного медиаканала выходит за безопасный лимит браузера.",
+    );
+  }
+  let loadedBytes = 0;
+  let loadedParts = 0;
+  const publishProgress = () => onProgress?.({
+    loadedBytes,
+    totalBytes,
+    loadedParts,
+    totalParts,
+  });
+  publishProgress();
+
+  const epochs: VerifiedRecordedMediaEpoch[] = [];
+  for (const epoch of manifest.epochs) {
+    const init = await fetchVerifiedRecordedMediaBytes({
+      url: epoch.initUrl,
+      byteLength: epoch.initByteLength,
+      sha256: epoch.initSha256,
+      accept: "video/mp4",
+    }, { signal, fetcher });
+    loadedBytes += init.byteLength;
+    loadedParts += 1;
+    publishProgress();
+
+    const segments: ArrayBuffer[] = [];
+    for (const segment of epoch.segments) {
+      const payload = await fetchVerifiedRecordedMediaBytes({
+        url: segment.url,
+        byteLength: segment.byteLength,
+        sha256: segment.sha256,
+        accept: "video/iso.segment",
+      }, { signal, fetcher });
+      segments.push(payload);
+      loadedBytes += payload.byteLength;
+      loadedParts += 1;
+      publishProgress();
+    }
+    epochs.push({ descriptor: epoch, init, segments });
+  }
+
+  // Bind the complete byte set to the same manifest generation at both ends
+  // of the transfer. A replacement during a long camera download fails closed.
+  const confirmed = await fetchObservationRecordedMediaManifest(source, {
+    signal,
+    fetcher,
+    expectedGenerationSha256: manifest.generationSha256,
+  });
+  if (manifestIdentity(confirmed) !== manifestIdentity(manifest)) {
+    throw new ObservationSessionContractError(
+      "Manifest записанного видео изменился во время полной загрузки.",
+    );
+  }
+  if (loadedBytes !== source.byteLength) {
+    throw new ObservationSessionContractError(
+      "Полная загрузка камеры не совпала с launch byte_length.",
+    );
+  }
+  return { manifest, epochs, byteLength: loadedBytes };
+}
+
+export function appendRecordedMediaBuffer(
+  sourceBuffer: SourceBuffer,
+  payload: ArrayBuffer,
+  signal: AbortSignal,
+): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const onUpdateEnd = () => {
+      cleanup();
+      resolve();
+    };
+    const onError = () => {
+      cleanup();
+      reject(new Error("SourceBuffer rejected archived fMP4 data"));
+    };
+    const onAbort = () => {
+      cleanup();
+      reject(new DOMException("Aborted", "AbortError"));
+    };
+    const cleanup = () => {
+      sourceBuffer.removeEventListener("updateend", onUpdateEnd);
+      sourceBuffer.removeEventListener("error", onError);
+      signal.removeEventListener("abort", onAbort);
+    };
+    if (signal.aborted) {
+      onAbort();
+      return;
+    }
+    sourceBuffer.addEventListener("updateend", onUpdateEnd, { once: true });
+    sourceBuffer.addEventListener("error", onError, { once: true });
+    signal.addEventListener("abort", onAbort, { once: true });
+    try {
+      sourceBuffer.appendBuffer(payload);
+    } catch (error) {
+      cleanup();
+      reject(error);
+    }
+  });
+}
+
+function videoHasSeekableArchive(
+  video: HTMLVideoElement,
+  declaredDurationSeconds: number,
+): boolean {
+  if (video.readyState < 1 || video.seekable.length < 1) return false;
+  return recordedMediaSeekableCoverage(
+    video.duration,
+    video.seekable.end(video.seekable.length - 1),
+    declaredDurationSeconds,
+    RECORDED_MEDIA_DURATION_TOLERANCE_SECONDS,
+    video.seekable.start(0),
+  );
+}
+
+function waitForSeekableArchive(
+  video: HTMLVideoElement,
+  declaredDurationSeconds: number,
+  signal: AbortSignal,
+): Promise<void> {
+  if (signal.aborted) return Promise.reject(new DOMException("Aborted", "AbortError"));
+  if (videoHasSeekableArchive(video, declaredDurationSeconds)) return Promise.resolve();
+  return new Promise((resolve, reject) => {
+    const events = ["loadedmetadata", "durationchange", "progress", "canplay"] as const;
+    const timeout = globalThis.setTimeout(() => {
+      cleanup();
+      reject(new Error("Archived camera did not become seekable"));
+    }, 20_000);
+    const cleanup = () => {
+      globalThis.clearTimeout(timeout);
+      for (const event of events) video.removeEventListener(event, onProgress);
+      video.removeEventListener("error", onError);
+      signal.removeEventListener("abort", onAbort);
+    };
+    const onProgress = () => {
+      if (!videoHasSeekableArchive(video, declaredDurationSeconds)) return;
+      cleanup();
+      resolve();
+    };
+    const onError = () => {
+      cleanup();
+      reject(new Error("Archived camera decode failed"));
+    };
+    const onAbort = () => {
+      cleanup();
+      reject(new DOMException("Aborted", "AbortError"));
+    };
+    for (const event of events) video.addEventListener(event, onProgress);
+    video.addEventListener("error", onError, { once: true });
+    signal.addEventListener("abort", onAbort, { once: true });
+  });
+}
+
+async function mountVerifiedRecordedEpoch(
+  video: HTMLVideoElement,
+  epoch: VerifiedRecordedMediaEpoch,
+  signal: AbortSignal,
+): Promise<() => void> {
+  const descriptor = epoch.descriptor;
+  if (
+    descriptor.mediaType === "video/mp4" ||
+    !globalThis.MediaSource ||
+    !MediaSource.isTypeSupported(descriptor.mediaType)
+  ) {
+    throw new Error("Archived camera codec is not supported");
+  }
+  const mediaSource = new MediaSource();
+  const objectUrl = URL.createObjectURL(mediaSource);
+  const cleanup = () => {
+    video.pause();
+    video.removeAttribute("src");
+    video.load();
+    URL.revokeObjectURL(objectUrl);
+  };
+  video.src = objectUrl;
+  try {
+    await new Promise<void>((resolve, reject) => {
+      const onOpen = () => {
+        cleanupListeners();
+        resolve();
+      };
+      const onAbort = () => {
+        cleanupListeners();
+        reject(new DOMException("Aborted", "AbortError"));
+      };
+      const cleanupListeners = () => {
+        mediaSource.removeEventListener("sourceopen", onOpen);
+        signal.removeEventListener("abort", onAbort);
+      };
+      if (signal.aborted) {
+        onAbort();
+        return;
+      }
+      mediaSource.addEventListener("sourceopen", onOpen, { once: true });
+      signal.addEventListener("abort", onAbort, { once: true });
+    });
+    if (signal.aborted || mediaSource.readyState !== "open") {
+      throw new DOMException("Aborted", "AbortError");
+    }
+    const sourceBuffer = mediaSource.addSourceBuffer(descriptor.mediaType);
+    await appendRecordedMediaBuffer(sourceBuffer, epoch.init, signal);
+    for (const segment of epoch.segments) {
+      await appendRecordedMediaBuffer(sourceBuffer, segment, signal);
+    }
+    if (signal.aborted || mediaSource.readyState !== "open" || sourceBuffer.updating) {
+      throw new Error("Archived camera MediaSource closed before full append");
+    }
+    mediaSource.endOfStream();
+    await waitForSeekableArchive(
+      video,
+      descriptor.timelineEndSeconds - descriptor.timelineStartSeconds,
+      signal,
+    );
+    return cleanup;
+  } catch (error) {
+    cleanup();
+    throw error;
+  }
+}
+
+export function RecordedFmp4Player({
+  source,
+  playback,
+  prepare = true,
+  sessionGate = "ready",
+  admissionKey = null,
+  onAdmissionChange,
+}: {
+  source: ObservationSourceDescriptor;
+  playback?: RecordedObservationPlayback | null;
+  prepare?: boolean;
+  sessionGate?: RecordedAdmissionPhase;
+  admissionKey?: string | null;
+  onAdmissionChange?: (state: RecordedCameraAdmissionState) => void;
+}) {
+  const videoRef = useRef<HTMLVideoElement>(null);
+  const onAdmissionChangeRef = useRef(onAdmissionChange);
+  onAdmissionChangeRef.current = onAdmissionChange;
+  const workerRef = useRef<{ admissionKey: string | null; generation: number } | null>(null);
+  if (!workerRef.current || workerRef.current.admissionKey !== admissionKey) {
+    recordedMediaWorkerGeneration += 1;
+    workerRef.current = { admissionKey, generation: recordedMediaWorkerGeneration };
+  }
+  const workerGeneration = workerRef.current.generation;
+  const reportAdmission = (next: RecordedCameraAdmissionState) => {
+    onAdmissionChangeRef.current?.({
+      ...next,
+      admissionKey,
+      workerGeneration,
+    });
+  };
+  const recordedDelivery = source.delivery?.kind === "recorded-fmp4-manifest"
+    ? source.delivery
+    : null;
+  const contract = useMemo(
+    () => sourceContract(source),
+    [
+      source.id,
+      source.label,
+      recordedDelivery?.id,
+      recordedDelivery?.url,
+      recordedDelivery?.mediaType,
+      recordedDelivery?.manifestGenerationSha256,
+      recordedDelivery?.byteLength,
+      recordedDelivery?.timelineStartSeconds,
+      recordedDelivery?.timelineEndSeconds,
+    ],
+  );
+  const [archive, setArchive] = useState<VerifiedRecordedMediaArchive | null>(null);
+  const [state, setState] = useState<"loading" | "ready" | "error">("loading");
+  const [readyGeneration, setReadyGeneration] = useState<string | null>(null);
+  const [progress, setProgress] = useState<RecordedMediaLoadProgress | null>(null);
+  const [bufferRevision, setBufferRevision] = useState(0);
+  const currentSeconds = playback?.currentSeconds ?? contract?.timelineStartSeconds ?? 0;
+  const epoch = useMemo(
+    () => selectRecordedMediaEpoch(archive?.manifest.epochs ?? [], currentSeconds),
+    [archive?.manifest.epochs, currentSeconds],
+  );
+  const verifiedEpoch = useMemo(
+    () => epoch
+      ? archive?.epochs.find(({ descriptor }) => descriptor.ordinal === epoch.ordinal) ?? null
+      : null,
+    [archive?.epochs, epoch],
+  );
+  const waitingForEpoch = Boolean(archive && !epoch);
+  const selectedGeneration = contract && epoch
+    ? `${contract.manifestGenerationSha256}:${epoch.ordinal}:${epoch.timelineStartSeconds}:${epoch.timelineEndSeconds}`
+    : null;
+  const visualState = recordedMediaPresentationState(
+    state,
+    readyGeneration,
+    selectedGeneration,
+    waitingForEpoch,
+    sessionGate,
+  );
+
+  useEffect(() => {
+    if (!contract) {
+      setArchive(null);
+      setProgress(null);
+      setReadyGeneration(null);
+      setState("error");
+      reportAdmission({
+        phase: "error",
+        byteLength: null,
+        message: "Некорректный descriptor записанной камеры.",
+      });
+      return;
+    }
+    if (!prepare) return;
+    const abort = new AbortController();
+    setArchive(null);
+    setProgress(null);
+    setReadyGeneration(null);
+    setState("loading");
+    reportAdmission({
+      phase: "loading",
+      byteLength: contract.byteLength,
+      message: null,
+    });
+    void fetchVerifiedRecordedMediaArchive(contract, {
+      signal: abort.signal,
+      onProgress: (next) => {
+        if (!abort.signal.aborted) setProgress(next);
+      },
+    })
+      .then((loaded) => {
+        if (abort.signal.aborted) return;
+        setArchive(loaded);
+      })
+      .catch((error: unknown) => {
+        if (abort.signal.aborted || (error instanceof DOMException && error.name === "AbortError")) {
+          return;
+        }
+        setArchive(null);
+        setReadyGeneration(null);
+        setState("error");
+        reportAdmission({
+          phase: "error",
+          byteLength: contract.byteLength,
+          message: "Архив записанной камеры не прошёл проверку.",
+        });
+      });
+    return () => abort.abort();
+  }, [admissionKey, contract, prepare]);
+
+  useEffect(() => {
+    if (!archive || !contract || !prepare) return;
+    const abort = new AbortController();
+    let disposed = false;
+    void (async () => {
+      for (const candidate of archive.epochs) {
+        const probe = document.createElement("video");
+        probe.muted = true;
+        probe.playsInline = true;
+        const cleanup = await mountVerifiedRecordedEpoch(probe, candidate, abort.signal);
+        cleanup();
+        if (disposed || abort.signal.aborted) return;
+      }
+      if (disposed || abort.signal.aborted) return;
+      reportAdmission({
+        phase: "ready",
+        byteLength: archive.byteLength,
+        message: null,
+      });
+    })().catch((error: unknown) => {
+      if (
+        disposed ||
+        abort.signal.aborted ||
+        (error instanceof DOMException && error.name === "AbortError")
+      ) return;
+      setReadyGeneration(null);
+      setState("error");
+      reportAdmission({
+        phase: "error",
+        byteLength: archive.byteLength,
+        message: "Не все codec epoch записанной камеры декодируются и доступны для seek.",
+      });
+    });
+    return () => {
+      disposed = true;
+      abort.abort();
+    };
+  }, [admissionKey, archive, contract, prepare]);
+
+  useEffect(() => {
+    const video = videoRef.current;
+    if (!video || !verifiedEpoch) return;
+    const epochDescriptor = verifiedEpoch.descriptor;
+    const generation = contract
+      ? `${contract.manifestGenerationSha256}:${epochDescriptor.ordinal}:${epochDescriptor.timelineStartSeconds}:${epochDescriptor.timelineEndSeconds}`
+      : null;
+    setReadyGeneration(null);
+    setState("loading");
+    const abort = new AbortController();
+    let disposed = false;
+    let cleanup: (() => void) | null = null;
+
+    const loadEpoch = async () => {
+      try {
+        cleanup = await mountVerifiedRecordedEpoch(video, verifiedEpoch, abort.signal);
+        if (disposed || abort.signal.aborted) {
+          cleanup();
+          cleanup = null;
+          return;
+        }
+        setBufferRevision((revision) => revision + 1);
+        setReadyGeneration(generation);
+        setState("ready");
+      } catch (error) {
+        if (
+          disposed ||
+          abort.signal.aborted ||
+          (error instanceof DOMException && error.name === "AbortError")
+        ) {
+          return;
+        }
+        setReadyGeneration(null);
+        setState("error");
+        reportAdmission({
+          phase: "error",
+          byteLength: archive?.byteLength ?? null,
+          message: "Записанная камера не стала seekable.",
+        });
+      }
+    };
+    void loadEpoch();
+
+    return () => {
+      disposed = true;
+      abort.abort();
+      cleanup?.();
+    };
+  }, [archive?.byteLength, contract, verifiedEpoch]);
+
+  useEffect(() => {
+    const video = videoRef.current;
+    if (!video || !epoch || visualState !== "ready") return;
+    const target = recordedMediaLocalTime(
+      epoch.timelineStartSeconds,
+      currentSeconds,
+      video.duration,
+    );
+    if (Number.isFinite(target) && Math.abs(video.currentTime - target) > 0.35) {
+      try {
+        video.currentTime = target;
+      } catch {
+        setReadyGeneration(null);
+        setState("error");
+        reportAdmission({
+          phase: "error",
+          byteLength: archive?.byteLength ?? null,
+          message: "Seek записанной камеры завершился ошибкой.",
+        });
+        return;
+      }
+    }
+    if (playback?.playing) {
+      void video.play().catch(() => undefined);
+    } else {
+      video.pause();
+    }
+  }, [archive?.byteLength, bufferRevision, currentSeconds, epoch, playback?.playing, visualState]);
+
+  const progressPercent = progress && progress.totalBytes > 0
+    ? Math.min(100, Math.floor((progress.loadedBytes / progress.totalBytes) * 100))
+    : 0;
+
+  return (
+    <div
+      className="recorded-media-player"
+      data-state={visualState}
+      aria-busy={visualState === "loading"}
+    >
+      <video
+        ref={videoRef}
+        className="observation-media__asset"
+        muted
+        playsInline
+        preload="auto"
+        aria-label={source.label}
+      />
+      {visualState !== "ready" ? (
+        <div
+          className="recorded-media-player__notice"
+          role={visualState === "error" ? "alert" : "status"}
+        >
+          {visualState === "waiting"
+            ? "Камера на этой позиции ещё не записывалась"
+            : visualState === "error"
+              ? "Записанное видео недоступно"
+              : archive
+                ? "Проверяем полную готовность записанного видео…"
+                : `Загружаем и проверяем записанное видео · ${progressPercent}%`}
+        </div>
+      ) : null}
+    </div>
+  );
+}
diff --git a/apps/control-station/src/components/RerunViewport.tsx b/apps/control-station/src/components/RerunViewport.tsx
index 67c521a..0668e58 100644
--- a/apps/control-station/src/components/RerunViewport.tsx
+++ b/apps/control-station/src/components/RerunViewport.tsx
@@ -1,5 +1,8 @@
 import { useEffect, useRef, useState } from "react";
 
+import type { SceneSettings } from "../sceneSettings";
+import type { RecordedAdmissionPhase } from "../core/observation/recordedSessionAdmission";
+
 export type RerunViewportStatus = "idle" | "loading" | "ready" | "error";
 
 export interface RerunSelection {
@@ -8,37 +11,575 @@ export interface RerunSelection {
   position?: [number, number, number];
 }
 
+export interface RerunPlaybackState {
+  recordingId: string;
+  timeline: string;
+  rangeNs: { min: number; max: number } | null;
+  currentNs: number;
+  playing: boolean;
+  /** Latest session-time value currently available to the browser receiver. */
+  bufferedEndNs: number | null;
+  /** Declared final session-time value, when the archive descriptor provides it. */
+  expectedEndNs: number | null;
+  /** Download progress in the closed interval 0..1, or null without a valid expectation. */
+  bufferProgress: number | null;
+  /** True only when the buffered range has reached the declared archive end. */
+  fullyBuffered: boolean;
+}
+
+export interface RerunPlaybackController {
+  seek: (timeNs: number) => void;
+  setPlaying: (playing: boolean) => void;
+  jumpToEnd: () => void;
+}
+
 export interface RerunViewportProps {
   sourceUrl: string;
+  recordedArtifact?: RecordedRrdArtifactDescriptor | null;
   followLive?: boolean;
+  autoplayWhenReady?: boolean;
+  presentationGate?: RecordedAdmissionPhase;
+  expectedTimelineStartSeconds?: number;
+  expectedTimelineEndSeconds?: number;
   onStatusChange?: (status: RerunViewportStatus, message?: string) => void;
   onSelectionChange?: (selection: RerunSelection | null) => void;
+  onPlaybackChange?: (state: RerunPlaybackState | null) => void;
+  onPlaybackControllerChange?: (controller: RerunPlaybackController | null) => void;
+  sceneSettings?: Pick<
+    SceneSettings,
+    | "accumulationSeconds"
+    | "showGrid"
+    | "showPoints"
+    | "showTrajectory"
+    | "pointSize"
+    | "palette"
+    | "customColor"
+  >;
+}
+
+export interface RecordedRrdArtifactDescriptor {
+  sourceUrl: string;
+  viewerSourceUrl: string;
+  byteLength: number;
+  sha256: string;
+}
+
+interface RerunBlueprintChannel {
+  endpointUrl: string;
+  channel: {
+    readonly ready: boolean;
+    send_rrd: (rrdBytes: Uint8Array) => void;
+    close: () => void;
+  };
+}
+
+interface RecordedRerunIdentity {
+  applicationId: "nodedc_mission_core_recorded";
+  recordingId: string;
+}
+
+const RECORDED_RRD_PATH = /^\/api\/v1\/observation-sessions\/[A-Za-z0-9][A-Za-z0-9._:-]{0,127}\/recording\.rrd$/;
+const RECORDED_BLUEPRINT_PATH = /^\/api\/v1\/observation-sessions\/[A-Za-z0-9][A-Za-z0-9._:-]{0,127}\/blueprint\.rrd$/;
+const MAX_BLUEPRINT_BYTES = 1_048_576;
+const BUFFER_END_TOLERANCE_NS = 1_000_000;
+const RECORDED_OPEN_MIN_TIMEOUT_MS = 120_000;
+const RECORDED_OPEN_MAX_TIMEOUT_MS = 1_800_000;
+const RECORDED_OPEN_GRACE_MS = 30_000;
+const RECORDED_OPEN_MIN_BYTES_PER_SECOND = 2 * 1024 * 1024;
+
+export function recordedOpenWatchdogTimeoutMs(byteLength: number): number {
+  if (!Number.isSafeInteger(byteLength) || byteLength < 4) {
+    throw new Error("Unsafe recorded RRD byte length");
+  }
+  const transferBudgetMs = Math.ceil(
+    (byteLength / RECORDED_OPEN_MIN_BYTES_PER_SECOND) * 1_000,
+  );
+  return Math.min(
+    RECORDED_OPEN_MAX_TIMEOUT_MS,
+    Math.max(RECORDED_OPEN_MIN_TIMEOUT_MS, transferBudgetMs + RECORDED_OPEN_GRACE_MS),
+  );
+}
+
+export function createRecordedOpenWatchdog<T>({
+  byteLength,
+  schedule,
+  cancel,
+  onTimeout,
+}: {
+  byteLength: number;
+  schedule: (callback: () => void, timeoutMs: number) => T;
+  cancel: (handle: T) => void;
+  onTimeout: () => void;
+}): { arm: () => void; clear: () => void; pending: () => boolean } {
+  const timeoutMs = recordedOpenWatchdogTimeoutMs(byteLength);
+  let handle: T | null = null;
+  return {
+    arm() {
+      if (handle !== null) return;
+      handle = schedule(() => {
+        handle = null;
+        onTimeout();
+      }, timeoutMs);
+    },
+    clear() {
+      if (handle === null) return;
+      cancel(handle);
+      handle = null;
+    },
+    pending: () => handle !== null,
+  };
+}
+
+export interface RecordedPlaybackBufferState {
+  bufferedEndNs: number | null;
+  expectedEndNs: number | null;
+  bufferProgress: number | null;
+  fullyBuffered: boolean;
+}
+
+/**
+ * A Rerun time range is usable as soon as it contains one finite timestamp.
+ * A first frame commonly has min === max; waiting for positive duration would
+ * needlessly keep that visible frame behind the loading screen.
+ */
+export function isUsableRecordedPlaybackRange(
+  rangeNs: { min: number; max: number } | null,
+): rangeNs is { min: number; max: number } {
+  return Boolean(
+    rangeNs &&
+    Number.isFinite(rangeNs.min) &&
+    Number.isFinite(rangeNs.max) &&
+    rangeNs.max >= rangeNs.min,
+  );
+}
+
+/** Describe progressive archive availability without gating first rendering. */
+export function recordedPlaybackBufferState(
+  rangeNs: { min: number; max: number } | null,
+  expectedTimelineEndSeconds?: number,
+  expectedTimelineStartSeconds?: number,
+): RecordedPlaybackBufferState {
+  const usableRange = isUsableRecordedPlaybackRange(rangeNs) ? rangeNs : null;
+  const bufferedEndNs = usableRange?.max ?? null;
+  if (expectedTimelineEndSeconds === undefined) {
+    return {
+      bufferedEndNs,
+      expectedEndNs: null,
+      bufferProgress: null,
+      fullyBuffered: usableRange !== null,
+    };
+  }
+  if (!Number.isFinite(expectedTimelineEndSeconds) || expectedTimelineEndSeconds < 0) {
+    return {
+      bufferedEndNs,
+      expectedEndNs: null,
+      bufferProgress: null,
+      fullyBuffered: false,
+    };
+  }
+
+  const expectedEndNs = expectedTimelineEndSeconds * 1_000_000_000;
+  const expectedStartNs = expectedTimelineStartSeconds === undefined
+    ? 0
+    : expectedTimelineStartSeconds * 1_000_000_000;
+  if (
+    !Number.isFinite(expectedEndNs) ||
+    !Number.isFinite(expectedStartNs) ||
+    expectedStartNs < 0 ||
+    expectedEndNs < expectedStartNs
+  ) {
+    return {
+      bufferedEndNs,
+      expectedEndNs: null,
+      bufferProgress: null,
+      fullyBuffered: false,
+    };
+  }
+  const fullyBuffered = usableRange !== null &&
+    Math.abs(usableRange.min - expectedStartNs) <= BUFFER_END_TOLERANCE_NS &&
+    Math.abs(usableRange.max - expectedEndNs) <= BUFFER_END_TOLERANCE_NS;
+  const expectedDurationNs = expectedEndNs - expectedStartNs;
+  const bufferProgress = bufferedEndNs === null
+    ? 0
+    : expectedDurationNs <= 0
+      ? (fullyBuffered ? 1 : 0)
+      : Math.min(1, Math.max(0, (bufferedEndNs - expectedStartNs) / expectedDurationNs));
+  return { bufferedEndNs, expectedEndNs, bufferProgress, fullyBuffered };
+}
+
+/** A recorded viewport is publishable only after its declared range is complete. */
+export function isRecordedPlaybackReady(
+  viewerStarted: boolean,
+  artifactVerified: boolean,
+  buffer: RecordedPlaybackBufferState,
+): boolean {
+  return viewerStarted && artifactVerified && buffer.fullyBuffered;
+}
+
+/** Keep the host scrubber and its controls disconnected from a partial archive. */
+export function recordedPlaybackRangeWhenReady(
+  rangeNs: { min: number; max: number } | null,
+  buffer: RecordedPlaybackBufferState,
+  artifactVerified: boolean,
+): { min: number; max: number } | null {
+  return artifactVerified && buffer.fullyBuffered && isUsableRecordedPlaybackRange(rangeNs)
+    ? rangeNs
+    : null;
+}
+
+/** Do not mount host timeline controls while a recorded generation is partial. */
+export function isRecordedPlaybackPresentationReady(
+  status: RerunViewportStatus,
+  playback: RerunPlaybackState | null,
+): boolean {
+  return status === "ready" &&
+    playback?.fullyBuffered === true &&
+    isUsableRecordedPlaybackRange(playback.rangeNs);
+}
+
+export function rerunPresentationStatus(
+  status: RerunViewportStatus,
+  gate: RecordedAdmissionPhase,
+  recorded: boolean,
+): RerunViewportStatus {
+  if (!recorded) return status;
+  if (status === "error" || gate === "error") return "error";
+  if (gate !== "ready") return "loading";
+  return status;
+}
+
+export function isRecordedPlaybackFullyBuffered(
+  rangeNs: { min: number; max: number } | null,
+  expectedTimelineEndSeconds?: number,
+): boolean {
+  return recordedPlaybackBufferState(rangeNs, expectedTimelineEndSeconds).fullyBuffered;
+}
+
+export function attemptRecordedAutoplay(
+  seekToStart: () => void,
+  startPlaying: () => void,
+): boolean {
+  try {
+    seekToStart();
+    startPlaying();
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+/**
+ * Admit autoplay once, after the viewer and the complete recorded range are
+ * ready. The attempt is consumed even if a vendor call throws: subsequent
+ * polling must never seek the operator back to the beginning a second time.
+ */
+export function createRecordedAutoplayGate(): {
+  attempt: (
+    viewerStarted: boolean,
+    fullyBuffered: boolean,
+    presentationReady: boolean,
+    rangeNs: { min: number; max: number } | null,
+    seekToStart: (startNs: number) => void,
+    startPlaying: () => void,
+  ) => boolean;
+  attempted: () => boolean;
+} {
+  let consumed = false;
+  return {
+    attempt(viewerStarted, fullyBuffered, presentationReady, rangeNs, seekToStart, startPlaying) {
+      if (
+        consumed ||
+        !viewerStarted ||
+        !fullyBuffered ||
+        !presentationReady ||
+        !isUsableRecordedPlaybackRange(rangeNs)
+      ) return false;
+      consumed = true;
+      return attemptRecordedAutoplay(
+        () => seekToStart(rangeNs.min),
+        startPlaying,
+      );
+    },
+    attempted: () => consumed,
+  };
+}
+
+export function canPublishRecordedPlaybackController(
+  readyToRender: boolean,
+  presentationGate: RecordedAdmissionPhase,
+): boolean {
+  return readyToRender && presentationGate === "ready";
+}
+
+export function createLatestAnimationFrameEmitter<T>({
+  emit,
+  requestFrame,
+  cancelFrame,
+}: {
+  emit: (value: T) => void;
+  requestFrame: (callback: FrameRequestCallback) => number;
+  cancelFrame: (handle: number) => void;
+}): { push: (value: T) => void; cancel: () => void } {
+  let frameHandle: number | null = null;
+  let latestValue: T | undefined;
+  let hasPendingValue = false;
+  let cancelled = false;
+
+  return {
+    push(value) {
+      if (cancelled) return;
+      latestValue = value;
+      hasPendingValue = true;
+      if (frameHandle !== null) return;
+      frameHandle = requestFrame(() => {
+        frameHandle = null;
+        if (cancelled || !hasPendingValue) return;
+        const valueToEmit = latestValue as T;
+        latestValue = undefined;
+        hasPendingValue = false;
+        emit(valueToEmit);
+      });
+    },
+    cancel() {
+      cancelled = true;
+      latestValue = undefined;
+      hasPendingValue = false;
+      if (frameHandle === null) return;
+      cancelFrame(frameHandle);
+      frameHandle = null;
+    },
+  };
+}
+
+export function resolveRerunSourceUrl(sourceUrl: string, origin: string): string {
+  const normalized = sourceUrl.trim();
+  if (!normalized.startsWith("/") || normalized.startsWith("//")) return normalized;
+
+  const base = new URL(origin);
+  return new URL(normalized, `${base.origin}/`).href;
+}
+
+/**
+ * The native Rerun HTTP receiver is the only browser API in 0.34.1 with a
+ * persistent incremental RRD decoder. Bind it to the exact immutable
+ * generation selected by the launch contract; arbitrary `send_rrd` byte
+ * slices are independently decoded files and are therefore invalid.
+ */
+export function resolveRecordedViewerSourceUrl(
+  descriptor: RecordedRrdArtifactDescriptor,
+  origin: string,
+): string {
+  const base = new URL(origin);
+  const expectedViewerSourceUrl = `${descriptor.sourceUrl}?generation=${descriptor.sha256}`;
+  const endpoint = new URL(descriptor.viewerSourceUrl, `${base.origin}/`);
+  if (
+    !RECORDED_RRD_PATH.test(descriptor.sourceUrl) ||
+    descriptor.viewerSourceUrl !== expectedViewerSourceUrl ||
+    endpoint.origin !== base.origin ||
+    endpoint.pathname !== descriptor.sourceUrl ||
+    endpoint.search !== `?generation=${descriptor.sha256}` ||
+    endpoint.hash ||
+    !Number.isSafeInteger(descriptor.byteLength) ||
+    descriptor.byteLength < 4 ||
+    !/^[a-f0-9]{64}$/.test(descriptor.sha256)
+  ) {
+    throw new Error("Unsafe recorded RRD viewer descriptor");
+  }
+  return endpoint.href;
+}
+
+export function rerunViewerInitialSource(
+  resolvedSourceUrl: string,
+): string {
+  return resolvedSourceUrl;
+}
+
+export function resolveRecordedBlueprintUrl(sourceUrl: string, origin: string): string | null {
+  const normalized = sourceUrl.trim();
+  if (!RECORDED_RRD_PATH.test(normalized)) return null;
+  const base = new URL(origin);
+  const endpoint = new URL(
+    normalized.replace(/\/recording\.rrd$/, "/blueprint.rrd"),
+    `${base.origin}/`,
+  );
+  return endpoint.origin === base.origin ? endpoint.href : null;
+}
+
+export async function fetchRecordedBlueprintRrd(
+  endpointUrl: string,
+  settings: Pick<
+    SceneSettings,
+    | "accumulationSeconds"
+    | "showGrid"
+    | "showPoints"
+    | "showTrajectory"
+    | "pointSize"
+    | "palette"
+    | "customColor"
+  >,
+  identity: RecordedRerunIdentity,
+  {
+    origin,
+    signal,
+    fetcher = globalThis.fetch,
+  }: {
+    origin: string;
+    signal?: AbortSignal;
+    fetcher?: typeof globalThis.fetch;
+  },
+): Promise<Uint8Array> {
+  const base = new URL(origin);
+  const endpoint = new URL(endpointUrl, base.origin);
+  if (
+    endpoint.origin !== base.origin ||
+    endpoint.search ||
+    endpoint.hash ||
+    !RECORDED_BLUEPRINT_PATH.test(endpoint.pathname) ||
+    !Number.isFinite(settings.accumulationSeconds) ||
+    settings.accumulationSeconds < 0 ||
+    settings.accumulationSeconds > 3600 ||
+    !Number.isFinite(settings.pointSize) ||
+    settings.pointSize < 0.1 ||
+    settings.pointSize > 32 ||
+    !["turbo", "viridis", "plasma", "grayscale", "custom"].includes(settings.palette) ||
+    !/^#[0-9A-Fa-f]{6}$/.test(settings.customColor) ||
+    identity.applicationId !== "nodedc_mission_core_recorded" ||
+    !/^[A-Za-z0-9][A-Za-z0-9._:-]{0,127}$/.test(identity.recordingId)
+  ) {
+    throw new Error("Unsafe recorded blueprint request");
+  }
+  const response = await fetcher(endpoint.href, {
+    method: "POST",
+    credentials: "same-origin",
+    headers: {
+      Accept: "application/vnd.rerun.rrd",
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({
+      application_id: identity.applicationId,
+      recording_id: identity.recordingId,
+      accumulation_seconds: settings.accumulationSeconds,
+      show_grid: settings.showGrid,
+      show_points: settings.showPoints,
+      show_trajectory: settings.showTrajectory,
+      point_size: settings.pointSize,
+      palette: settings.palette,
+      custom_color: settings.customColor,
+    }),
+    signal,
+  });
+  const contentType = response.headers.get("Content-Type")?.split(";", 1)[0].trim();
+  const declaredLength = Number(response.headers.get("Content-Length"));
+  if (
+    !response.ok ||
+    contentType !== "application/vnd.rerun.rrd" ||
+    (Number.isFinite(declaredLength) && declaredLength > MAX_BLUEPRINT_BYTES)
+  ) {
+    throw new Error("Invalid recorded blueprint response");
+  }
+  const payload = new Uint8Array(await response.arrayBuffer());
+  if (
+    payload.byteLength < 4 ||
+    payload.byteLength > MAX_BLUEPRINT_BYTES ||
+    payload[0] !== 0x52 ||
+    payload[1] !== 0x52 ||
+    payload[2] !== 0x46 ||
+    payload[3] !== 0x32
+  ) {
+    throw new Error("Invalid recorded blueprint RRD");
+  }
+  return payload;
 }
 
 export function RerunViewport({
   sourceUrl,
+  recordedArtifact = null,
   followLive = false,
+  autoplayWhenReady = false,
+  presentationGate = "ready",
+  expectedTimelineStartSeconds,
+  expectedTimelineEndSeconds,
   onStatusChange,
   onSelectionChange,
+  onPlaybackChange,
+  onPlaybackControllerChange,
+  sceneSettings,
 }: RerunViewportProps) {
   const hostRef = useRef<HTMLDivElement>(null);
   const [status, setStatus] = useState<RerunViewportStatus>(sourceUrl ? "loading" : "idle");
+  const [recordingBufferProgress, setRecordingBufferProgress] = useState<number | null>(null);
   const [retryNonce, setRetryNonce] = useState(0);
+  const blueprintChannelRef = useRef<RerunBlueprintChannel | null>(null);
+  const recordedIdentityRef = useRef<RecordedRerunIdentity | null>(null);
+  const presentationGateRef = useRef(presentationGate);
+  presentationGateRef.current = presentationGate;
+  const [blueprintChannelRevision, setBlueprintChannelRevision] = useState(0);
+  const recordedBlueprintUrl = sourceUrl
+    ? resolveRecordedBlueprintUrl(sourceUrl, window.location.origin)
+    : null;
+  const presentationStatus = rerunPresentationStatus(
+    status,
+    presentationGate,
+    recordedArtifact !== null,
+  );
 
   useEffect(() => {
     const normalizedSource = sourceUrl.trim();
     const host = hostRef.current;
     if (!normalizedSource || !host) {
       setStatus("idle");
+      setRecordingBufferProgress(null);
       onStatusChange?.("idle");
       onSelectionChange?.(null);
+      onPlaybackChange?.(null);
+      onPlaybackControllerChange?.(null);
+      return;
+    }
+    const isRecordedSource = RECORDED_RRD_PATH.test(normalizedSource);
+    let resolvedSource: string;
+    try {
+      if (isRecordedSource) {
+        if (!recordedArtifact || recordedArtifact.sourceUrl !== normalizedSource) {
+          throw new Error("Recorded generation is missing");
+        }
+        resolvedSource = resolveRecordedViewerSourceUrl(
+          recordedArtifact,
+          window.location.origin,
+        );
+      } else {
+        resolvedSource = resolveRerunSourceUrl(normalizedSource, window.location.origin);
+      }
+    } catch {
+      host.replaceChildren();
+      setStatus("error");
+      setRecordingBufferProgress(null);
+      onStatusChange?.("error", "Запись не привязана к проверенному поколению архива.");
+      onSelectionChange?.(null);
+      onPlaybackChange?.(null);
+      onPlaybackControllerChange?.(null);
       return;
     }
 
     let disposed = false;
     let disposeViewer: (() => void) | undefined;
     let recordingOpenTimer: number | undefined;
+    let recordedOpenWatchdog: {
+      arm: () => void;
+      clear: () => void;
+      pending: () => boolean;
+    } | null = null;
+    let playbackRangeTimer: number | undefined;
     let recordingOpened = false;
+    let recordingOpenTimedOut = false;
+    let viewerStartResolved = false;
+    // The backend serves this exact digest-bound URL or rejects it with 412.
+    // Presentation still waits for Rerun to decode the complete declared range.
+    const artifactVerified = true;
+    let recordedSceneAdmitted = !isRecordedSource;
+    let publishPlaybackBufferState: (() => void) | null = null;
+    let playbackState: RerunPlaybackState | null = null;
+    const recordedAutoplay = createRecordedAutoplayGate();
+    let blueprintChannel: RerunBlueprintChannel | null = null;
     const unsubscribers: Array<() => void> = [];
     const unsubscribeAll = () => {
       while (unsubscribers.length > 0) {
@@ -50,11 +591,38 @@ export function RerunViewport({
         }
       }
     };
-    const clearRecordingOpenTimer = () => {
-      if (recordingOpenTimer === undefined) return;
-      window.clearTimeout(recordingOpenTimer);
-      recordingOpenTimer = undefined;
+    const clearRecordedAdmissionWatchdog = () => recordedOpenWatchdog?.clear();
+    const clearLiveRecordingOpenTimer = () => {
+      if (recordingOpenTimer !== undefined) {
+        window.clearTimeout(recordingOpenTimer);
+        recordingOpenTimer = undefined;
+      }
     };
+    const clearRecordingTimers = () => {
+      clearRecordedAdmissionWatchdog();
+      clearLiveRecordingOpenTimer();
+    };
+    const clearPlaybackRangeTimer = () => {
+      if (playbackRangeTimer === undefined) return;
+      window.clearInterval(playbackRangeTimer);
+      playbackRangeTimer = undefined;
+    };
+    const emitPlayback = (patch: Partial<RerunPlaybackState> = {}) => {
+      if (!playbackState || disposed) return;
+      playbackState = { ...playbackState, ...patch };
+      if (recordedSceneAdmitted) onPlaybackChange?.(playbackState);
+    };
+    const playbackTimeUpdates = createLatestAnimationFrameEmitter<{
+      recordingId: string;
+      timeNs: number;
+    }>({
+      emit: ({ recordingId, timeNs }) => {
+        if (disposed || recordingId !== playbackState?.recordingId) return;
+        emitPlayback({ currentNs: timeNs });
+      },
+      requestFrame: (callback) => window.requestAnimationFrame(callback),
+      cancelFrame: (handle) => window.cancelAnimationFrame(handle),
+    });
     const reportError = (message: string) => {
       if (disposed) return;
       setStatus("error");
@@ -63,6 +631,7 @@ export function RerunViewport({
 
     host.replaceChildren();
     setStatus("loading");
+    setRecordingBufferProgress(null);
     onStatusChange?.("loading");
 
     void import("@rerun-io/web-viewer")
@@ -77,10 +646,33 @@ export function RerunViewport({
         disposeViewer = () => {
           if (viewerDisposed) return;
           viewerDisposed = true;
-          clearRecordingOpenTimer();
+          clearRecordingTimers();
+          clearPlaybackRangeTimer();
+          playbackTimeUpdates.cancel();
+          // Pause before closing the receiver. Besides matching the operator
+          // lifecycle, this prevents the old WASM render loop from advancing
+          // while React prepares the next saved session.
+          if (playbackState) {
+            try {
+              viewer.set_playing(playbackState.recordingId, false);
+            } catch {
+              // The recording may already have been removed by the receiver.
+            }
+          }
           unsubscribeAll();
+          onPlaybackControllerChange?.(null);
+          onPlaybackChange?.(null);
+          if (blueprintChannelRef.current === blueprintChannel) {
+            blueprintChannelRef.current = null;
+          }
+          recordedIdentityRef.current = null;
           try {
-            if (viewer.ready) viewer.close(normalizedSource);
+            blueprintChannel?.channel.close();
+          } catch {
+            // The viewer may already have closed all auxiliary channels.
+          }
+          try {
+            if (viewer.ready) viewer.close(resolvedSource);
           } catch {
             // The receiver may already be gone after a transport failure.
           }
@@ -92,30 +684,223 @@ export function RerunViewport({
           }
           host.replaceChildren();
         };
+        if (isRecordedSource && recordedArtifact) {
+          recordedOpenWatchdog = createRecordedOpenWatchdog({
+            byteLength: recordedArtifact.byteLength,
+            schedule: (callback, timeoutMs) => window.setTimeout(callback, timeoutMs),
+            cancel: (handle) => window.clearTimeout(handle),
+            onTimeout: () => {
+              if (disposed || recordedSceneAdmitted) return;
+              recordingOpenTimedOut = true;
+              disposeViewer?.();
+              reportError("Поколение записи не загрузилось полностью за расчётное время.");
+            },
+          });
+        }
 
         unsubscribers.push(
           viewer.on("recording_open", (event) => {
-            if (disposed) return;
+            if (disposed || recordingOpened) return;
             recordingOpened = true;
-            clearRecordingOpenTimer();
-            if (followLive) {
-              try {
-                // The backend blueprint owns native `Following`; the host only
-                // selects its live timeline once. Repeated SetTime calls would
-                // force Rerun out of Following and create needless repaints.
-                viewer.set_active_timeline(event.recording_id, "stream_time");
-              } catch {
-                // A receiver can disappear between the event and the WASM call.
+            if (
+              recordedBlueprintUrl &&
+              event.application_id === "nodedc_mission_core_recorded" &&
+              /^[A-Za-z0-9][A-Za-z0-9._:-]{0,127}$/.test(event.recording_id)
+            ) {
+              const current = recordedIdentityRef.current;
+              if (
+                current?.applicationId !== event.application_id ||
+                current.recordingId !== event.recording_id
+              ) {
+                recordedIdentityRef.current = {
+                  applicationId: event.application_id,
+                  recordingId: event.recording_id,
+                };
+                setBlueprintChannelRevision((revision) => revision + 1);
               }
             }
-            setStatus("ready");
-            onStatusChange?.("ready");
+            if (!isRecordedSource) clearLiveRecordingOpenTimer();
+            // Durable Mission Core recordings use a zero-based session clock.
+            // Keeping wall-clock capture_time as a secondary RRD timeline is
+            // useful for audit, but the operator scrubber must remain a small,
+            // exact duration value that JavaScript can seek without precision
+            // loss.
+            const timeline = followLive ? "stream_time" : "session_time";
+            try {
+              // The backend blueprint owns native `Following`; the host only
+              // selects its live timeline once. Repeated SetTime calls would
+              // force Rerun out of Following and create needless repaints.
+              viewer.set_active_timeline(event.recording_id, timeline);
+            } catch {
+              // A receiver can disappear between the event and the WASM call.
+            }
+            let rangeNs = viewer.get_time_range(event.recording_id, timeline);
+            let currentNs = viewer.get_current_time(event.recording_id, timeline);
+            let playing = viewer.get_playing(event.recording_id);
+            if (!followLive && playing) {
+              try {
+                viewer.set_playing(event.recording_id, false);
+                playing = false;
+              } catch {
+                // Loading can race a receiver closing after a failed request.
+              }
+            }
+            const initialRecordedBuffer = recordedPlaybackBufferState(
+              rangeNs,
+              expectedTimelineEndSeconds,
+              expectedTimelineStartSeconds,
+            );
+            playbackState = {
+              recordingId: event.recording_id,
+              timeline,
+              // The host timeline must not expose a partially decoded archive.
+              // Buffer telemetry below still reports download progress.
+              rangeNs: followLive ? rangeNs : null,
+              currentNs,
+              playing,
+              ...(followLive
+                ? {
+                    bufferedEndNs: rangeNs?.max ?? null,
+                    expectedEndNs: null,
+                    bufferProgress: null,
+                    fullyBuffered: true,
+                  }
+                : initialRecordedBuffer),
+            };
+            if (followLive) onPlaybackChange?.(playbackState);
+            const playbackController: RerunPlaybackController = {
+              seek: (timeNs) => {
+                const range = playbackState?.rangeNs;
+                if (!range) return;
+                const clamped = Math.min(Math.max(timeNs, range.min), range.max);
+                viewer.set_current_time(event.recording_id, timeline, clamped);
+                emitPlayback({ currentNs: clamped, playing: false });
+              },
+              setPlaying: (playing) => {
+                viewer.set_playing(event.recording_id, playing);
+                emitPlayback({ playing });
+              },
+              jumpToEnd: () => {
+                const range = viewer.get_time_range(event.recording_id, timeline);
+                if (!range) return;
+                viewer.set_current_time(event.recording_id, timeline, range.max);
+                emitPlayback({ rangeNs: range, currentNs: range.max, playing: false });
+              },
+            };
+            let playbackControllerPublished = false;
+            if (followLive) {
+              playbackControllerPublished = true;
+              onPlaybackControllerChange?.(playbackController);
+            }
+            let readyPublished = false;
+            const publishBufferedState = () => {
+              if (disposed || !playbackState) return;
+              try {
+                rangeNs = viewer.get_time_range(event.recording_id, timeline);
+                currentNs = viewer.get_current_time(event.recording_id, timeline);
+                playing = viewer.get_playing(event.recording_id);
+              } catch {
+                return;
+              }
+              const recordedBuffer = recordedPlaybackBufferState(
+                rangeNs,
+                expectedTimelineEndSeconds,
+                expectedTimelineStartSeconds,
+              );
+              if (!followLive && artifactVerified) {
+                setRecordingBufferProgress(recordedBuffer.bufferProgress);
+              }
+              const readyToRender = followLive
+                ? viewerStartResolved
+                : isRecordedPlaybackReady(viewerStartResolved, artifactVerified, recordedBuffer);
+              const presentationReady = presentationGateRef.current === "ready";
+              if (!followLive && (!readyToRender || !presentationReady) && playing) {
+                try {
+                  viewer.set_playing(event.recording_id, false);
+                  playing = false;
+                } catch {
+                  return;
+                }
+              }
+              if (autoplayWhenReady && !followLive && readyToRender) {
+                const autoplayStarted = recordedAutoplay.attempt(
+                  viewerStartResolved,
+                  recordedBuffer.fullyBuffered,
+                  presentationReady,
+                  rangeNs,
+                  (autoplayStartNs) => {
+                    viewer.set_current_time(event.recording_id, timeline, autoplayStartNs);
+                    currentNs = autoplayStartNs;
+                  },
+                  () => {
+                    viewer.set_playing(event.recording_id, true);
+                  },
+                );
+                if (autoplayStarted) {
+                  playing = true;
+                }
+              }
+              emitPlayback({
+                rangeNs: followLive
+                  ? rangeNs
+                  : recordedPlaybackRangeWhenReady(rangeNs, recordedBuffer, artifactVerified),
+                currentNs,
+                playing,
+                ...(followLive
+                  ? {
+                      bufferedEndNs: rangeNs?.max ?? null,
+                      expectedEndNs: null,
+                      bufferProgress: null,
+                      fullyBuffered: true,
+                    }
+                  : recordedBuffer),
+              });
+              if (readyToRender && !readyPublished) {
+                readyPublished = true;
+                if (!followLive) clearRecordedAdmissionWatchdog();
+                if (!followLive) setRecordingBufferProgress(1);
+                recordedSceneAdmitted = true;
+                if (!followLive) onPlaybackChange?.(playbackState);
+                setStatus("ready");
+                onStatusChange?.("ready");
+              }
+              if (
+                !followLive &&
+                !playbackControllerPublished &&
+                canPublishRecordedPlaybackController(readyToRender, presentationGateRef.current)
+              ) {
+                playbackControllerPublished = true;
+                onPlaybackControllerChange?.(playbackController);
+              }
+            };
+            publishPlaybackBufferState = publishBufferedState;
+            clearPlaybackRangeTimer();
+            publishBufferedState();
+            playbackRangeTimer = window.setInterval(publishBufferedState, 500);
+          }),
+        );
+
+        unsubscribers.push(
+          viewer.on("time_update", (event) => {
+            if (disposed || event.recording_id !== playbackState?.recordingId) return;
+            playbackTimeUpdates.push({
+              recordingId: event.recording_id,
+              timeNs: event.time,
+            });
+          }),
+          viewer.on("play", (event) => {
+            if (disposed || event.recording_id !== playbackState?.recordingId) return;
+            emitPlayback({ playing: true });
+          }),
+          viewer.on("pause", (event) => {
+            if (disposed || event.recording_id !== playbackState?.recordingId) return;
+            emitPlayback({ playing: false });
           }),
         );
 
         unsubscribers.push(
           viewer.on("selection_change", (event) => {
-            if (disposed) return;
+            if (disposed || !recordedSceneAdmitted) return;
             const entity = event.items.find((item) => item.type === "entity");
             if (!entity || entity.type !== "entity") {
               onSelectionChange?.(null);
@@ -130,37 +915,67 @@ export function RerunViewport({
         );
 
         try {
-          await viewer.start(
-            normalizedSource,
-            host,
-            {
-              width: "100%",
-              height: "100%",
-              theme: "dark",
-              hide_welcome_screen: true,
-              enable_history: false,
-              allow_fullscreen: false,
+          // `panel_state_overrides` is part of Rerun's runtime AppOptions but
+          // omitted from the public WebViewerOptions declaration in 0.34.1.
+          // Its generated TypeScript declaration says `hidden`, while the
+          // WASM constructor actually deserializes the Rust enum `Hidden`.
+          // Keep the post-start overrides below as a compatibility fallback.
+          const viewerOptions = {
+            width: "100%",
+            height: "100%",
+            theme: "dark",
+            hide_welcome_screen: true,
+            enable_history: false,
+            allow_fullscreen: false,
+            panel_state_overrides: {
+              top: "Hidden",
+              blueprint: "Hidden",
+              selection: "Hidden",
+              time: "Hidden",
             },
+          } as Parameters<typeof viewer.start>[2] & {
+            panel_state_overrides: Record<string, "Hidden">;
+          };
+          await viewer.start(
+            rerunViewerInitialSource(resolvedSource),
+            host,
+            viewerOptions,
             null,
           );
           if (disposed) {
             disposeViewer();
             return;
           }
+          viewerStartResolved = true;
+          if (isRecordedSource && !recordedSceneAdmitted) recordedOpenWatchdog?.arm();
+          publishPlaybackBufferState?.();
 
           viewer.override_panel_state("top", "hidden");
           viewer.override_panel_state("blueprint", "hidden");
           viewer.override_panel_state("selection", "hidden");
           viewer.override_panel_state("time", "hidden");
 
-          if (!recordingOpened) {
+          if (recordedBlueprintUrl) {
+            const channel = viewer.open_channel("missioncore/recorded-blueprint");
+            blueprintChannel = { endpointUrl: recordedBlueprintUrl, channel };
+            blueprintChannelRef.current = blueprintChannel;
+            setBlueprintChannelRevision((revision) => revision + 1);
+          }
+
+          if (!recordingOpened && !isRecordedSource) {
             recordingOpenTimer = window.setTimeout(() => {
+              recordingOpenTimedOut = true;
+              disposeViewer?.();
               reportError("Визуализатор запущен, но поток записи не открылся.");
             }, 12_000);
           }
         } catch {
           disposeViewer();
-          reportError("Не удалось запустить встроенный визуализатор.");
+          if (!recordingOpenTimedOut && !disposed) {
+            reportError(isRecordedSource
+              ? "Запись не прошла атомарную проверку целостности."
+              : "Не удалось запустить встроенный визуализатор.");
+          }
         }
       })
       .catch(() => {
@@ -171,26 +986,98 @@ export function RerunViewport({
 
     return () => {
       disposed = true;
-      clearRecordingOpenTimer();
+      clearRecordingTimers();
+      clearPlaybackRangeTimer();
+      playbackTimeUpdates.cancel();
       unsubscribeAll();
       disposeViewer?.();
       onSelectionChange?.(null);
+      onPlaybackControllerChange?.(null);
+      onPlaybackChange?.(null);
     };
-  }, [followLive, onSelectionChange, onStatusChange, retryNonce, sourceUrl]);
+  }, [
+    autoplayWhenReady,
+    expectedTimelineEndSeconds,
+    expectedTimelineStartSeconds,
+    followLive,
+    onPlaybackChange,
+    onPlaybackControllerChange,
+    onSelectionChange,
+    onStatusChange,
+    recordedArtifact?.byteLength,
+    recordedArtifact?.sha256,
+    recordedArtifact?.sourceUrl,
+    recordedArtifact?.viewerSourceUrl,
+    retryNonce,
+    sourceUrl,
+  ]);
+
+  useEffect(() => {
+    if (!recordedBlueprintUrl || !sceneSettings) return;
+    const active = blueprintChannelRef.current;
+    const identity = recordedIdentityRef.current;
+    if (
+      !active ||
+      !identity ||
+      active.endpointUrl !== recordedBlueprintUrl ||
+      !active.channel.ready
+    ) return;
+    const abort = new AbortController();
+    void fetchRecordedBlueprintRrd(recordedBlueprintUrl, sceneSettings, identity, {
+      origin: window.location.origin,
+      signal: abort.signal,
+    }).then((payload) => {
+      if (
+        abort.signal.aborted ||
+        blueprintChannelRef.current !== active ||
+        recordedIdentityRef.current !== identity ||
+        !active.channel.ready
+      ) {
+        return;
+      }
+      active.channel.send_rrd(payload);
+    }).catch(() => {
+      // The recording remains usable with its embedded default blueprint.
+      // A later settings change retries through the same small channel.
+    });
+    return () => abort.abort();
+  }, [
+    blueprintChannelRevision,
+    recordedBlueprintUrl,
+    sceneSettings?.accumulationSeconds,
+    sceneSettings?.customColor,
+    sceneSettings?.palette,
+    sceneSettings?.pointSize,
+    sceneSettings?.showPoints,
+    sceneSettings?.showTrajectory,
+    sceneSettings?.showGrid,
+  ]);
 
   return (
-    <div className="rerun-viewport" data-status={status}>
-      <div ref={hostRef} className="rerun-viewport__canvas" />
-      {status === "loading" ? (
+    <div className="rerun-viewport" data-status={presentationStatus}>
+      <div
+        ref={hostRef}
+        className="rerun-viewport__canvas"
+        data-presented={recordedArtifact === null || presentationStatus === "ready" ? "true" : "false"}
+      />
+      {presentationStatus === "loading" ? (
         <div className="rerun-viewport__notice" role="status">
           <span className="busy-indicator" aria-hidden="true" />
           <div>
-            <strong>Подключаем визуальный источник</strong>
-            <span>Запуск встроенного визуализатора Rerun.</span>
+            <strong>
+              {recordedBlueprintUrl ? "Загружаем запись" : "Подключаем визуальный источник"}
+            </strong>
+            <span>
+              {recordedBlueprintUrl
+                ? recordingBufferProgress === null
+                  ? "Запуск визуализатора и проверка архива."
+                  : `Загрузка и декодирование · ${Math.round(recordingBufferProgress * 100)}%`
+                : "Запуск встроенного визуализатора Rerun."}
+            </span>
           </div>
         </div>
       ) : null}
-      {status === "error" ? (
+      {presentationStatus === "error" ? (
         <div className="rerun-viewport__notice rerun-viewport__notice--error" role="alert">
           <div>
             <strong>Источник не открыт</strong>
diff --git a/apps/control-station/src/core/observation/recordedObservationSources.ts b/apps/control-station/src/core/observation/recordedObservationSources.ts
new file mode 100644
index 0000000..a0fe15a
--- /dev/null
+++ b/apps/control-station/src/core/observation/recordedObservationSources.ts
@@ -0,0 +1,84 @@
+import type { ObservationSourceDescriptor } from "../runtime/contracts";
+import type { ObservationSessionReplayLaunch } from "./sessionArchive";
+
+export function recordedObservationSources(
+  launch: ObservationSessionReplayLaunch | null,
+): ObservationSourceDescriptor[] {
+  if (!launch) return [];
+  const spatial: ObservationSourceDescriptor = {
+    id: "recorded.spatial.primary",
+    sourceId: "recorded.spatial.primary",
+    semanticChannelId: "spatial.point-cloud.recorded",
+    label: "Сохранённая пространственная сцена",
+    description: "Облако точек и траектория из записи Rerun",
+    modality: "point-cloud",
+    role: "primary",
+    availability: "available",
+    transport: "recording",
+    endpointLabel: "RRD · session_time",
+    previewUrl: launch.sourceUrl,
+    delivery: null,
+    activation: null,
+    provider: {
+      pluginId: "missioncore.session-archive",
+      pluginVersion: "1",
+      modelId: "recorded-spatial",
+      compatibilityProfileId: null,
+    },
+    binding: {},
+    capabilities: {
+      overlay: false,
+      fullscreen: true,
+      resizable: false,
+      defaultVisible: true,
+      timelineMode: "recorded",
+      seekable: true,
+      sessionRecording: true,
+      clockId: launch.timeline,
+      spatialRegistration: "native",
+    },
+  };
+  const media = launch.mediaSources.map((source, index): ObservationSourceDescriptor => ({
+    id: source.id,
+    sourceId: source.id,
+    semanticChannelId: "camera.video.recorded",
+    label: source.label,
+    description: "Сохранённый видеоканал на общей временной шкале сессии",
+    modality: "video",
+    role: "auxiliary",
+    availability: "available",
+    transport: "recording",
+    endpointLabel: "Сохранённая сессия",
+    previewUrl: null,
+    delivery: {
+      id: `${launch.sessionId}:${source.id}`,
+      kind: "recorded-fmp4-manifest",
+      url: source.manifestUrl,
+      mediaType: source.mediaType,
+      manifestGenerationSha256: source.manifestGenerationSha256,
+      byteLength: source.byteLength,
+      timelineStartSeconds: source.timelineStartSeconds,
+      timelineEndSeconds: source.timelineEndSeconds,
+    },
+    activation: null,
+    provider: {
+      pluginId: "missioncore.session-archive",
+      pluginVersion: "1",
+      modelId: "recorded-media",
+      compatibilityProfileId: null,
+    },
+    binding: {},
+    capabilities: {
+      overlay: true,
+      fullscreen: true,
+      resizable: true,
+      defaultVisible: index < 2,
+      timelineMode: "recorded",
+      seekable: true,
+      sessionRecording: true,
+      clockId: "session_time",
+      spatialRegistration: "unresolved",
+    },
+  }));
+  return [spatial, ...media];
+}
diff --git a/apps/control-station/src/core/observation/recordedSessionAdmission.ts b/apps/control-station/src/core/observation/recordedSessionAdmission.ts
new file mode 100644
index 0000000..e149bc1
--- /dev/null
+++ b/apps/control-station/src/core/observation/recordedSessionAdmission.ts
@@ -0,0 +1,123 @@
+// A device-agnostic frontend safety policy. Sixteen channels covers multi-rig
+// vehicles while the independent byte/concurrency limits keep admission
+// bounded. OPFS-backed sealed generations are the planned scaling path beyond
+// this in-memory laboratory policy.
+export const MAX_RECORDED_CAMERA_SOURCES = 16;
+export const MAX_RECORDED_MEDIA_SOURCE_BYTES = 128 * 1024 * 1024;
+export const MAX_RECORDED_SESSION_CAMERA_BYTES = 512 * 1024 * 1024;
+export const MAX_CONCURRENT_RECORDED_CAMERA_PREPARATIONS = 1;
+
+export type RecordedAdmissionPhase = "loading" | "ready" | "error";
+export type RecordedCameraAdmissionPhase = "pending" | "loading" | "ready" | "error";
+
+export interface RecordedCameraAdmissionState {
+  phase: RecordedCameraAdmissionPhase;
+  byteLength: number | null;
+  message: string | null;
+  admissionKey?: string | null;
+  workerGeneration?: number;
+}
+
+export type RecordedCameraAdmissionMap = Readonly<Record<string, RecordedCameraAdmissionState>>;
+
+export interface RecordedCameraAdmissionDescriptor {
+  id: string;
+  byteLength: number;
+}
+
+export function recordedCameraDescriptorPreflight(
+  sources: readonly RecordedCameraAdmissionDescriptor[],
+): RecordedAdmissionPhase {
+  if (sources.length > MAX_RECORDED_CAMERA_SOURCES) return "error";
+  if (new Set(sources.map(({ id }) => id)).size !== sources.length) return "error";
+  let totalBytes = 0;
+  for (const source of sources) {
+    if (
+      !source.id ||
+      !Number.isSafeInteger(source.byteLength) ||
+      source.byteLength < 1 ||
+      source.byteLength > MAX_RECORDED_MEDIA_SOURCE_BYTES
+    ) return "error";
+    totalBytes += source.byteLength;
+    if (!Number.isSafeInteger(totalBytes) || totalBytes > MAX_RECORDED_SESSION_CAMERA_BYTES) {
+      return "error";
+    }
+  }
+  return "ready";
+}
+
+export function initialRecordedCameraAdmissions(
+  sourceIds: readonly string[],
+  declaredByteLengths: Readonly<Record<string, number>> = {},
+): Record<string, RecordedCameraAdmissionState> {
+  return Object.fromEntries(sourceIds.map((sourceId) => [sourceId, {
+    phase: "pending" as const,
+    byteLength: declaredByteLengths[sourceId] ?? null,
+    message: null,
+  }]));
+}
+
+export function recordedSessionAdmissionPhase(
+  spatialPhase: RecordedAdmissionPhase,
+  sourceIds: readonly string[],
+  cameras: RecordedCameraAdmissionMap,
+): RecordedAdmissionPhase {
+  if (sourceIds.length > MAX_RECORDED_CAMERA_SOURCES || spatialPhase === "error") {
+    return "error";
+  }
+  let totalBytes = 0;
+  for (const sourceId of sourceIds) {
+    const camera = cameras[sourceId];
+    if (!camera || camera.phase === "error") return "error";
+    if (camera.phase === "ready" && camera.byteLength === null) return "error";
+    if (camera.byteLength !== null) {
+      if (
+        !Number.isSafeInteger(camera.byteLength) ||
+        camera.byteLength < 1 ||
+        camera.byteLength > MAX_RECORDED_MEDIA_SOURCE_BYTES
+      ) return "error";
+      totalBytes += camera.byteLength;
+    }
+  }
+  if (totalBytes > MAX_RECORDED_SESSION_CAMERA_BYTES) return "error";
+  if (spatialPhase !== "ready") return "loading";
+  return sourceIds.every((sourceId) => cameras[sourceId]?.phase === "ready")
+    ? "ready"
+    : "loading";
+}
+
+export function nextRecordedCameraPreparationIds(
+  sourceIds: readonly string[],
+  cameras: RecordedCameraAdmissionMap,
+  preferredSourceIds: ReadonlySet<string> = new Set(),
+  concurrency = MAX_CONCURRENT_RECORDED_CAMERA_PREPARATIONS,
+): string[] {
+  if (!Number.isInteger(concurrency) || concurrency < 1) return [];
+  const pending = sourceIds.filter((sourceId) => {
+    const phase = cameras[sourceId]?.phase;
+    return phase === "pending" || phase === "loading" || phase === undefined;
+  });
+  pending.sort((left, right) => (
+    Number(cameras[right]?.phase === "loading") - Number(cameras[left]?.phase === "loading") ||
+    Number(preferredSourceIds.has(right)) - Number(preferredSourceIds.has(left)) ||
+    sourceIds.indexOf(left) - sourceIds.indexOf(right)
+  ));
+  return pending.slice(0, concurrency);
+}
+
+export function mergeRecordedCameraAdmission(
+  current: RecordedCameraAdmissionState,
+  next: RecordedCameraAdmissionState,
+): RecordedCameraAdmissionState {
+  const normalized = next.byteLength === null && current.byteLength !== null
+    ? { ...next, byteLength: current.byteLength }
+    : next;
+  const currentWorker = current.workerGeneration ?? 0;
+  const nextWorker = normalized.workerGeneration ?? currentWorker;
+  if (nextWorker < currentWorker) return current;
+  if (current.phase === "error") return current;
+  if (nextWorker > currentWorker) return normalized;
+  if (normalized.phase === "error") return normalized;
+  if (current.phase === "ready") return current;
+  return normalized;
+}
diff --git a/apps/control-station/src/core/observation/sessionArchive.ts b/apps/control-station/src/core/observation/sessionArchive.ts
new file mode 100644
index 0000000..fbc9656
--- /dev/null
+++ b/apps/control-station/src/core/observation/sessionArchive.ts
@@ -0,0 +1,1282 @@
+import {
+  MAX_RECORDED_CAMERA_SOURCES,
+  MAX_RECORDED_MEDIA_SOURCE_BYTES,
+  MAX_RECORDED_SESSION_CAMERA_BYTES,
+} from "./recordedSessionAdmission";
+
+export type ObservationSessionStatus =
+  | "recording"
+  | "ready"
+  | "degraded"
+  | "interrupted"
+  | "failed";
+
+export interface ObservationSessionSummary {
+  id: string;
+  label: string;
+  startedAtUtc: string;
+  completedAtUtc: string | null;
+  status: ObservationSessionStatus;
+  modalities: readonly string[];
+  durationSeconds: number;
+  replayable: boolean;
+  preparation: ObservationSessionCatalogPreparation | null;
+}
+
+export interface ObservationSessionCatalog {
+  items: readonly ObservationSessionSummary[];
+}
+
+export interface ObservationSessionReplayLaunch {
+  kind: "rerun-recording";
+  sessionId: string;
+  sourceUrl: string;
+  viewerSourceUrl: string;
+  mediaType: "application/vnd.rerun.rrd";
+  timeline: "session_time";
+  timelineStartSeconds: number;
+  timelineEndSeconds: number;
+  seekable: true;
+  byteLength: number;
+  sha256: string;
+  playback: {
+    speed: number;
+    loop: boolean;
+  };
+  mediaSources: readonly ObservationRecordedMediaSource[];
+}
+
+export type ObservationSessionPreparationState =
+  | "queued"
+  | "validating"
+  | "exporting"
+  | "finalizing"
+  | "failed"
+  | "cancelled";
+
+export interface ObservationSessionPreparation {
+  preparationId: string;
+  sessionId: string;
+  state: ObservationSessionPreparationState;
+  progress: number | null;
+  updatedAtUtc: string;
+  statusUrl: string;
+  cancellable: boolean;
+  retryable: boolean;
+  error: string | null;
+}
+
+export interface ObservationSessionCatalogPreparation {
+  preparationId: string;
+  state: ObservationSessionPreparationState | "ready";
+  progress: number | null;
+  updatedAtUtc: string;
+  cancellable: boolean;
+  retryable: boolean;
+  error: string | null;
+}
+
+export type ObservationSessionReplayResponse =
+  | { kind: "ready"; launch: ObservationSessionReplayLaunch }
+  | { kind: "preparing"; preparation: ObservationSessionPreparation };
+
+export interface ObservationRecordedMediaSource {
+  id: string;
+  label: string;
+  modality: "video";
+  manifestUrl: string;
+  manifestGenerationSha256: string;
+  byteLength: number;
+  mediaType: "video/mp4";
+  timelineStartSeconds: number;
+  timelineEndSeconds: number;
+  seekable: true;
+  synchronization: "host-arrival-best-effort";
+}
+
+export interface ObservationRecordedMediaEpoch {
+  ordinal: number;
+  timelineStartSeconds: number;
+  timelineEndSeconds: number;
+  mediaType: string;
+  initUrl: string;
+  initByteLength: number;
+  initSha256: string;
+  segmentCount: number;
+  segmentUrlPrefix: string;
+  segments: readonly ObservationRecordedMediaSegment[];
+}
+
+export interface ObservationRecordedMediaSegment {
+  sequence: number;
+  url: string;
+  byteLength: number;
+  sha256: string;
+}
+
+export interface ObservationRecordedMediaManifest {
+  sourceId: string;
+  generationSha256: string;
+  byteLength: number;
+  timelineStartSeconds: number;
+  timelineEndSeconds: number;
+  synchronization: "host-arrival-best-effort";
+  epochs: readonly ObservationRecordedMediaEpoch[];
+}
+
+export type ObservationSessionFetch = (
+  input: RequestInfo | URL,
+  init?: RequestInit,
+) => Promise<Response>;
+
+const SESSION_STATUSES = new Set<ObservationSessionStatus>([
+  "recording",
+  "ready",
+  "degraded",
+  "interrupted",
+  "failed",
+]);
+
+const CATALOG_KEYS = new Set(["items"]);
+const ITEM_KEYS = new Set([
+  "id",
+  "label",
+  "started_at_utc",
+  "completed_at_utc",
+  "status",
+  "modalities",
+  "duration_seconds",
+  "replayable",
+  "preparation",
+]);
+const CATALOG_PREPARATION_KEYS = new Set([
+  "preparation_id",
+  "state",
+  "progress",
+  "updated_at_utc",
+  "cancellable",
+  "retryable",
+  "error",
+]);
+const REPLAY_KEYS = new Set(["schema_version", "launch"]);
+const REPLAY_LAUNCH_KEYS = new Set([
+  "kind",
+  "session_id",
+  "source_url",
+  "viewer_source_url",
+  "media_type",
+  "timeline",
+  "timeline_start_seconds",
+  "timeline_end_seconds",
+  "seekable",
+  "byte_length",
+  "sha256",
+  "playback",
+  "media_sources",
+]);
+const REPLAY_PLAYBACK_KEYS = new Set(["speed", "loop"]);
+const PREPARATION_KEYS = new Set(["schema_version", "preparation"]);
+const PREPARATION_VALUE_KEYS = new Set([
+  "preparation_id",
+  "session_id",
+  "state",
+  "progress",
+  "updated_at_utc",
+  "status_url",
+  "cancellable",
+  "retryable",
+  "error",
+]);
+const RECORDED_MEDIA_SOURCE_KEYS = new Set([
+  "id",
+  "label",
+  "modality",
+  "manifest_url",
+  "manifest_generation_sha256",
+  "byte_length",
+  "media_type",
+  "timeline_start_seconds",
+  "timeline_end_seconds",
+  "seekable",
+  "synchronization",
+]);
+const RECORDED_MEDIA_MANIFEST_KEYS = new Set([
+  "schema_version",
+  "source_id",
+  "generation_sha256",
+  "byte_length",
+  "timeline_start_seconds",
+  "timeline_end_seconds",
+  "synchronization",
+  "epochs",
+]);
+const RECORDED_MEDIA_EPOCH_KEYS = new Set([
+  "ordinal",
+  "timeline_start_seconds",
+  "timeline_end_seconds",
+  "media_type",
+  "init_url",
+  "init_byte_length",
+  "init_sha256",
+  "segment_count",
+  "segment_url_prefix",
+  "segments",
+]);
+const RECORDED_MEDIA_SEGMENT_KEYS = new Set([
+  "sequence",
+  "url",
+  "byte_length",
+  "sha256",
+]);
+const SAFE_ID = /^[A-Za-z0-9][A-Za-z0-9._:-]{0,127}$/;
+const SAFE_MODALITY = /^[A-Za-z0-9][A-Za-z0-9._:-]{0,63}$/;
+const ISO_WITH_TIMEZONE = /^\d{4}-\d{2}-\d{2}T.+(?:Z|[+-]\d{2}:\d{2})$/;
+const SHA256 = /^[a-f0-9]{64}$/;
+const SAFE_RECORDING_URL = /^\/api\/v1\/observation-sessions\/[A-Za-z0-9._%:-]+\/recording\.rrd$/;
+const SAFE_PREPARATION_URL = /^\/api\/v1\/observation-sessions\/[A-Za-z0-9._%:-]+\/recording-preparation$/;
+const SAFE_MEDIA_MANIFEST_URL = /^\/api\/v1\/observation-sessions\/[A-Za-z0-9._%:-]+\/media\/[A-Za-z0-9._%-]+\/manifest$/;
+const SAFE_MP4_MEDIA_TYPE = /^video\/mp4(?:; codecs="[A-Za-z0-9.,_-]+")?$/;
+const MAX_RECORDED_INIT_BYTES = 8 * 1024 * 1024;
+const MAX_RECORDED_SEGMENT_BYTES = 64 * 1024 * 1024;
+
+export class ObservationSessionContractError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "ObservationSessionContractError";
+  }
+}
+
+export class ObservationSessionApiError extends Error {
+  readonly status: number;
+
+  constructor(message: string, status = 0) {
+    super(message);
+    this.name = "ObservationSessionApiError";
+    this.status = status;
+  }
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+function assertExactKeys(
+  value: Record<string, unknown>,
+  allowed: ReadonlySet<string>,
+  context: string,
+): void {
+  const unknown = Object.keys(value).filter((key) => !allowed.has(key));
+  if (unknown.length > 0) {
+    throw new ObservationSessionContractError(
+      `${context} содержит неизвестные поля: ${unknown.sort().join(", ")}.`,
+    );
+  }
+}
+
+function requireString(
+  value: unknown,
+  field: string,
+  maximumLength: number,
+): string {
+  if (typeof value !== "string") {
+    throw new ObservationSessionContractError(`Поле ${field} должно быть строкой.`);
+  }
+  const normalized = value.trim();
+  if (!normalized || normalized.length > maximumLength) {
+    throw new ObservationSessionContractError(`Поле ${field} имеет недопустимую длину.`);
+  }
+  return normalized;
+}
+
+function requireUtcTimestamp(value: unknown, field: string): string {
+  const timestamp = requireString(value, field, 64);
+  if (!ISO_WITH_TIMEZONE.test(timestamp) || !Number.isFinite(Date.parse(timestamp))) {
+    throw new ObservationSessionContractError(
+      `Поле ${field} должно быть ISO-датой с часовым поясом.`,
+    );
+  }
+  return timestamp;
+}
+
+function optionalUtcTimestamp(value: unknown, field: string): string | null {
+  return value === null ? null : requireUtcTimestamp(value, field);
+}
+
+function requireStatus(value: unknown): ObservationSessionStatus {
+  if (typeof value !== "string" || !SESSION_STATUSES.has(value as ObservationSessionStatus)) {
+    throw new ObservationSessionContractError("Поле status содержит неизвестное состояние сессии.");
+  }
+  return value as ObservationSessionStatus;
+}
+
+function requireModalities(value: unknown): string[] {
+  if (!Array.isArray(value)) {
+    throw new ObservationSessionContractError("Поле modalities должно быть массивом.");
+  }
+  const modalities: string[] = [];
+  for (const entry of value) {
+    const modality = requireString(entry, "modalities[]", 64);
+    if (!SAFE_MODALITY.test(modality)) {
+      throw new ObservationSessionContractError(
+        `Модальность ${modality} не является безопасным идентификатором.`,
+      );
+    }
+    if (!modalities.includes(modality)) modalities.push(modality);
+  }
+  return modalities;
+}
+
+function decodeItem(value: unknown, index: number): ObservationSessionSummary {
+  if (!isRecord(value)) {
+    throw new ObservationSessionContractError(`Элемент sessions[${index}] должен быть объектом.`);
+  }
+  assertExactKeys(value, ITEM_KEYS, `Элемент sessions[${index}]`);
+
+  const id = requireString(value.id, "id", 128);
+  if (!SAFE_ID.test(id)) {
+    throw new ObservationSessionContractError(
+      `Идентификатор сессии ${id} не является безопасным непрозрачным идентификатором.`,
+    );
+  }
+  const startedAtUtc = requireUtcTimestamp(value.started_at_utc, "started_at_utc");
+  const completedAtUtc = optionalUtcTimestamp(value.completed_at_utc, "completed_at_utc");
+  if (completedAtUtc && Date.parse(completedAtUtc) < Date.parse(startedAtUtc)) {
+    throw new ObservationSessionContractError(
+      `Сессия ${id} завершилась раньше времени начала.`,
+    );
+  }
+  if (
+    typeof value.duration_seconds !== "number" ||
+    !Number.isFinite(value.duration_seconds) ||
+    value.duration_seconds < 0
+  ) {
+    throw new ObservationSessionContractError(
+      `Поле duration_seconds сессии ${id} должно быть неотрицательным числом.`,
+    );
+  }
+  if (typeof value.replayable !== "boolean") {
+    throw new ObservationSessionContractError(`Поле replayable сессии ${id} должно быть boolean.`);
+  }
+
+  return {
+    id,
+    label: requireString(value.label, "label", 256),
+    startedAtUtc,
+    completedAtUtc,
+    status: requireStatus(value.status),
+    modalities: requireModalities(value.modalities),
+    durationSeconds: value.duration_seconds,
+    replayable: value.replayable,
+    preparation: decodeCatalogPreparation(value.preparation, id),
+  };
+}
+
+function decodeCatalogPreparation(
+  value: unknown,
+  sessionId: string,
+): ObservationSessionCatalogPreparation | null {
+  if (value === null || value === undefined) return null;
+  if (!isRecord(value)) {
+    throw new ObservationSessionContractError(
+      `Подготовка сессии ${sessionId} должна быть объектом или null.`,
+    );
+  }
+  assertExactKeys(value, CATALOG_PREPARATION_KEYS, `Подготовка сессии ${sessionId}`);
+  const preparationId = requireString(
+    value.preparation_id,
+    `preparation(${sessionId}).preparation_id`,
+    128,
+  );
+  if (!SAFE_ID.test(preparationId)) {
+    throw new ObservationSessionContractError("Каталог содержит небезопасный preparation id.");
+  }
+  const allowedStates = new Set([...PREPARATION_STATES, "ready"]);
+  if (typeof value.state !== "string" || !allowedStates.has(value.state)) {
+    throw new ObservationSessionContractError("Каталог содержит неизвестную фазу подготовки.");
+  }
+  const progress = value.progress === null
+    ? null
+    : requireFiniteNumber(value.progress, `preparation(${sessionId}).progress`, { maximum: 1 });
+  if (typeof value.cancellable !== "boolean" || typeof value.retryable !== "boolean") {
+    throw new ObservationSessionContractError(
+      "Каталог содержит некорректные флаги подготовки.",
+    );
+  }
+  if (
+    value.error !== undefined &&
+    value.error !== null &&
+    (typeof value.error !== "string" || !value.error.trim() || value.error.length > 1_000)
+  ) {
+    throw new ObservationSessionContractError("Каталог содержит некорректную ошибку подготовки.");
+  }
+  return {
+    preparationId,
+    state: value.state as ObservationSessionCatalogPreparation["state"],
+    progress,
+    updatedAtUtc: requireUtcTimestamp(
+      value.updated_at_utc,
+      `preparation(${sessionId}).updated_at_utc`,
+    ),
+    cancellable: value.cancellable,
+    retryable: value.retryable,
+    error: typeof value.error === "string" ? value.error.trim() : null,
+  };
+}
+
+export function sortObservationSessions(
+  items: readonly ObservationSessionSummary[],
+): ObservationSessionSummary[] {
+  return [...items].sort((left, right) => {
+    const timestampOrder = Date.parse(right.startedAtUtc) - Date.parse(left.startedAtUtc);
+    return timestampOrder || left.id.localeCompare(right.id);
+  });
+}
+
+export function decodeObservationSessionCatalog(payload: unknown): ObservationSessionCatalog {
+  if (!isRecord(payload)) {
+    throw new ObservationSessionContractError("Каталог сессий должен быть объектом.");
+  }
+  assertExactKeys(payload, CATALOG_KEYS, "Каталог сессий");
+  if (!Array.isArray(payload.items)) {
+    throw new ObservationSessionContractError("Каталог сессий не содержит массив items.");
+  }
+
+  const items = payload.items.map(decodeItem);
+  const ids = new Set<string>();
+  for (const item of items) {
+    if (ids.has(item.id)) {
+      throw new ObservationSessionContractError(
+        `Каталог сессий содержит повторяющийся id ${item.id}.`,
+      );
+    }
+    ids.add(item.id);
+  }
+  return { items: sortObservationSessions(items) };
+}
+
+function requireFiniteNumber(
+  value: unknown,
+  field: string,
+  {
+    minimum = 0,
+    maximum = Number.POSITIVE_INFINITY,
+    integer = false,
+  }: { minimum?: number; maximum?: number; integer?: boolean } = {},
+): number {
+  if (
+    typeof value !== "number" ||
+    !Number.isFinite(value) ||
+    value < minimum ||
+    value > maximum ||
+    (integer && !Number.isInteger(value))
+  ) {
+    throw new ObservationSessionContractError(`Поле ${field} содержит недопустимое число.`);
+  }
+  return value;
+}
+
+export function decodeObservationSessionReplay(
+  payload: unknown,
+): ObservationSessionReplayLaunch {
+  if (!isRecord(payload)) {
+    throw new ObservationSessionContractError("Ответ запуска повтора должен быть объектом.");
+  }
+  assertExactKeys(payload, REPLAY_KEYS, "Ответ запуска повтора");
+  if (payload.schema_version !== "missioncore.observation-session-replay/v2") {
+    throw new ObservationSessionContractError("Сервер вернул неподдерживаемый контракт повтора.");
+  }
+  if (!isRecord(payload.launch)) {
+    throw new ObservationSessionContractError("Ответ запуска не содержит descriptor записи.");
+  }
+  const launch = payload.launch;
+  assertExactKeys(launch, REPLAY_LAUNCH_KEYS, "Descriptor записи");
+  if (launch.kind !== "rerun-recording") {
+    throw new ObservationSessionContractError("Сервер не вернул seekable Rerun recording.");
+  }
+  const sessionId = requireString(launch.session_id, "launch.session_id", 128);
+  if (!SAFE_ID.test(sessionId)) {
+    throw new ObservationSessionContractError("Descriptor содержит небезопасный session id.");
+  }
+  const sourceUrl = requireString(launch.source_url, "launch.source_url", 512);
+  const expectedSourceUrl = `/api/v1/observation-sessions/${encodeURIComponent(sessionId)}/recording.rrd`;
+  if (
+    !SAFE_RECORDING_URL.test(sourceUrl) ||
+    sourceUrl !== expectedSourceUrl ||
+    sourceUrl.includes("..")
+  ) {
+    throw new ObservationSessionContractError(
+      "Запись должна публиковаться по безопасному same-origin API URL.",
+    );
+  }
+  if (launch.media_type !== "application/vnd.rerun.rrd" || launch.timeline !== "session_time") {
+    throw new ObservationSessionContractError("Descriptor записи содержит неподдерживаемый формат.");
+  }
+  if (launch.seekable !== true) {
+    throw new ObservationSessionContractError("Сохранённая сессия должна быть seekable.");
+  }
+  const timelineStartSeconds = requireFiniteNumber(
+    launch.timeline_start_seconds,
+    "launch.timeline_start_seconds",
+  );
+  const timelineEndSeconds = requireFiniteNumber(
+    launch.timeline_end_seconds,
+    "launch.timeline_end_seconds",
+  );
+  if (timelineEndSeconds < timelineStartSeconds) {
+    throw new ObservationSessionContractError("Диапазон времени записи задан в обратном порядке.");
+  }
+  if (typeof launch.sha256 !== "string" || !SHA256.test(launch.sha256)) {
+    throw new ObservationSessionContractError("Descriptor записи не содержит SHA-256.");
+  }
+  const viewerSourceUrl = requireString(
+    launch.viewer_source_url,
+    "launch.viewer_source_url",
+    640,
+  );
+  const expectedViewerSourceUrl = `${expectedSourceUrl}?generation=${launch.sha256}`;
+  if (viewerSourceUrl !== expectedViewerSourceUrl) {
+    throw new ObservationSessionContractError(
+      "URL визуализатора должен быть канонически привязан к SHA-256 поколения записи.",
+    );
+  }
+  if (!isRecord(launch.playback)) {
+    throw new ObservationSessionContractError("Descriptor записи не содержит playback.");
+  }
+  assertExactKeys(launch.playback, REPLAY_PLAYBACK_KEYS, "Параметры playback");
+  const speed = requireFiniteNumber(launch.playback.speed, "launch.playback.speed", {
+    maximum: 100,
+  });
+  if (typeof launch.playback.loop !== "boolean") {
+    throw new ObservationSessionContractError("Поле launch.playback.loop должно быть boolean.");
+  }
+  if (
+    !Array.isArray(launch.media_sources) ||
+    launch.media_sources.length > MAX_RECORDED_CAMERA_SOURCES
+  ) {
+    throw new ObservationSessionContractError(
+      "Descriptor записи содержит некорректный каталог медиаканалов.",
+    );
+  }
+  const mediaSources = launch.media_sources.map((entry, index) =>
+    decodeRecordedMediaSource(
+      entry,
+      index,
+      sessionId,
+      timelineStartSeconds,
+      timelineEndSeconds,
+    ));
+  if (new Set(mediaSources.map(({ id }) => id)).size !== mediaSources.length) {
+    throw new ObservationSessionContractError(
+      "Descriptor записи содержит повторяющиеся медиаканалы.",
+    );
+  }
+  const mediaByteLength = mediaSources.reduce((total, source) => total + source.byteLength, 0);
+  if (
+    !Number.isSafeInteger(mediaByteLength) ||
+    mediaByteLength > MAX_RECORDED_SESSION_CAMERA_BYTES
+  ) {
+    throw new ObservationSessionContractError(
+      "Совокупный объём записанных медиаканалов превышает безопасный лимит браузера.",
+    );
+  }
+  return {
+    kind: "rerun-recording",
+    sessionId,
+    sourceUrl,
+    viewerSourceUrl,
+    mediaType: "application/vnd.rerun.rrd",
+    timeline: "session_time",
+    timelineStartSeconds,
+    timelineEndSeconds,
+    seekable: true,
+    byteLength: requireFiniteNumber(launch.byte_length, "launch.byte_length", {
+      minimum: 1,
+      maximum: Number.MAX_SAFE_INTEGER,
+      integer: true,
+    }),
+    sha256: launch.sha256,
+    playback: { speed, loop: launch.playback.loop },
+    mediaSources,
+  };
+}
+
+const PREPARATION_STATES = new Set<ObservationSessionPreparationState>([
+  "queued",
+  "validating",
+  "exporting",
+  "finalizing",
+  "failed",
+  "cancelled",
+]);
+
+export function decodeObservationSessionPreparation(
+  payload: unknown,
+  expectedSessionId: string,
+): ObservationSessionPreparation {
+  if (!SAFE_ID.test(expectedSessionId)) {
+    throw new ObservationSessionContractError(
+      "Идентификатор подготавливаемой сессии имеет недопустимый формат.",
+    );
+  }
+  if (!isRecord(payload)) {
+    throw new ObservationSessionContractError("Ответ подготовки записи должен быть объектом.");
+  }
+  assertExactKeys(payload, PREPARATION_KEYS, "Ответ подготовки записи");
+  if (payload.schema_version !== "missioncore.observation-session-preparation/v1") {
+    throw new ObservationSessionContractError("Сервер вернул неподдерживаемый контракт подготовки.");
+  }
+  if (!isRecord(payload.preparation)) {
+    throw new ObservationSessionContractError("Ответ не содержит состояние подготовки записи.");
+  }
+  const value = payload.preparation;
+  assertExactKeys(value, PREPARATION_VALUE_KEYS, "Состояние подготовки записи");
+  const preparationId = requireString(value.preparation_id, "preparation.preparation_id", 128);
+  const sessionId = requireString(value.session_id, "preparation.session_id", 128);
+  if (!SAFE_ID.test(preparationId) || !SAFE_ID.test(sessionId) || sessionId !== expectedSessionId) {
+    throw new ObservationSessionContractError(
+      "Состояние подготовки содержит несовместимый идентификатор.",
+    );
+  }
+  if (
+    typeof value.state !== "string" ||
+    !PREPARATION_STATES.has(value.state as ObservationSessionPreparationState)
+  ) {
+    throw new ObservationSessionContractError("Состояние подготовки неизвестно клиенту.");
+  }
+  const state = value.state as ObservationSessionPreparationState;
+  const terminal = state === "failed" || state === "cancelled";
+  const progress = value.progress === null
+    ? null
+    : requireFiniteNumber(value.progress, "preparation.progress", { maximum: 1 });
+  const updatedAtUtc = requireUtcTimestamp(value.updated_at_utc, "preparation.updated_at_utc");
+  const statusUrl = requireString(value.status_url, "preparation.status_url", 512);
+  const expectedStatusUrl =
+    `/api/v1/observation-sessions/${encodeURIComponent(sessionId)}/recording-preparation`;
+  if (
+    !SAFE_PREPARATION_URL.test(statusUrl) ||
+    statusUrl !== expectedStatusUrl ||
+    statusUrl.includes("..")
+  ) {
+    throw new ObservationSessionContractError(
+      "Статус подготовки должен использовать канонический same-origin API URL.",
+    );
+  }
+  if (typeof value.cancellable !== "boolean") {
+    throw new ObservationSessionContractError("Поле preparation.cancellable должно быть boolean.");
+  }
+  if (value.retryable !== undefined && typeof value.retryable !== "boolean") {
+    throw new ObservationSessionContractError("Поле preparation.retryable должно быть boolean.");
+  }
+  if (
+    value.error !== undefined &&
+    value.error !== null &&
+    (typeof value.error !== "string" || !value.error.trim() || value.error.length > 1_000)
+  ) {
+    throw new ObservationSessionContractError("Поле preparation.error имеет недопустимый формат.");
+  }
+  if (!terminal && (value.retryable === true || (value.error !== undefined && value.error !== null))) {
+    throw new ObservationSessionContractError(
+      "Незавершённая подготовка не должна содержать terminal-поля.",
+    );
+  }
+  if (terminal && value.cancellable) {
+    throw new ObservationSessionContractError(
+      "Завершённую подготовку нельзя помечать как cancellable.",
+    );
+  }
+  return {
+    preparationId,
+    sessionId,
+    state,
+    progress,
+    updatedAtUtc,
+    statusUrl,
+    cancellable: value.cancellable,
+    retryable: terminal && value.retryable === true,
+    error: terminal && typeof value.error === "string" ? value.error.trim() : null,
+  };
+}
+
+function decodeRecordedMediaSource(
+  value: unknown,
+  index: number,
+  sessionId: string,
+  recordingStartSeconds: number,
+  recordingEndSeconds: number,
+): ObservationRecordedMediaSource {
+  if (!isRecord(value)) {
+    throw new ObservationSessionContractError(`Медиаканал ${index} должен быть объектом.`);
+  }
+  assertExactKeys(value, RECORDED_MEDIA_SOURCE_KEYS, `Медиаканал ${index}`);
+  const id = requireString(value.id, `media_sources[${index}].id`, 128);
+  if (!SAFE_ID.test(id) || !id.startsWith("recorded.camera.")) {
+    throw new ObservationSessionContractError("Медиаканал содержит небезопасный opaque id.");
+  }
+  if (value.modality !== "video" || value.media_type !== "video/mp4") {
+    throw new ObservationSessionContractError("Медиаканал имеет неподдерживаемый формат.");
+  }
+  const manifestUrl = requireString(
+    value.manifest_url,
+    `media_sources[${index}].manifest_url`,
+    512,
+  );
+  if (
+    typeof value.manifest_generation_sha256 !== "string" ||
+    !SHA256.test(value.manifest_generation_sha256)
+  ) {
+    throw new ObservationSessionContractError(
+      "Медиаканал не содержит immutable generation SHA-256.",
+    );
+  }
+  const sessionPrefix = `/api/v1/observation-sessions/${encodeURIComponent(sessionId)}/media/`;
+  if (
+    !SAFE_MEDIA_MANIFEST_URL.test(manifestUrl) ||
+    !manifestUrl.startsWith(sessionPrefix) ||
+    manifestUrl.includes("..")
+  ) {
+    throw new ObservationSessionContractError(
+      "Manifest медиаканала должен использовать безопасный same-origin API URL.",
+    );
+  }
+  const timelineStartSeconds = requireFiniteNumber(
+    value.timeline_start_seconds,
+    `media_sources[${index}].timeline_start_seconds`,
+  );
+  const timelineEndSeconds = requireFiniteNumber(
+    value.timeline_end_seconds,
+    `media_sources[${index}].timeline_end_seconds`,
+  );
+  if (
+    timelineEndSeconds <= timelineStartSeconds ||
+    timelineStartSeconds < recordingStartSeconds ||
+    timelineEndSeconds > recordingEndSeconds
+  ) {
+    throw new ObservationSessionContractError("Временной диапазон медиаканала некорректен.");
+  }
+  if (value.seekable !== true || value.synchronization !== "host-arrival-best-effort") {
+    throw new ObservationSessionContractError("Медиаканал не поддерживает ожидаемый повтор.");
+  }
+  return {
+    id,
+    label: requireString(value.label, `media_sources[${index}].label`, 160),
+    modality: "video",
+    manifestUrl,
+    manifestGenerationSha256: value.manifest_generation_sha256,
+    byteLength: requireFiniteNumber(
+      value.byte_length,
+      `media_sources[${index}].byte_length`,
+      { minimum: 1, maximum: MAX_RECORDED_MEDIA_SOURCE_BYTES, integer: true },
+    ),
+    mediaType: "video/mp4",
+    timelineStartSeconds,
+    timelineEndSeconds,
+    seekable: true,
+    synchronization: "host-arrival-best-effort",
+  };
+}
+
+export function decodeObservationRecordedMediaManifest(
+  payload: unknown,
+  source: ObservationRecordedMediaSource,
+): ObservationRecordedMediaManifest {
+  if (!isRecord(payload)) {
+    throw new ObservationSessionContractError("Manifest записанного видео должен быть объектом.");
+  }
+  assertExactKeys(payload, RECORDED_MEDIA_MANIFEST_KEYS, "Manifest записанного видео");
+  if (
+    payload.schema_version !== "missioncore.observation-recorded-media/v2" ||
+    payload.source_id !== source.id ||
+    typeof payload.generation_sha256 !== "string" ||
+    !SHA256.test(payload.generation_sha256) ||
+    payload.generation_sha256 !== source.manifestGenerationSha256 ||
+    payload.synchronization !== "host-arrival-best-effort" ||
+    !Array.isArray(payload.epochs) ||
+    payload.epochs.length < 1 ||
+    payload.epochs.length > 1_000
+  ) {
+    throw new ObservationSessionContractError("Manifest записанного видео несовместим.");
+  }
+  const manifestBase = source.manifestUrl.slice(0, -"/manifest".length);
+  const manifestByteLength = requireFiniteNumber(payload.byte_length, "manifest.byte_length", {
+    minimum: 1,
+    maximum: MAX_RECORDED_MEDIA_SOURCE_BYTES,
+    integer: true,
+  });
+  if (manifestByteLength !== source.byteLength) {
+    throw new ObservationSessionContractError(
+      "Размер manifest не совпадает с launch descriptor медиаканала.",
+    );
+  }
+  const manifestTimelineStartSeconds = requireFiniteNumber(
+    payload.timeline_start_seconds,
+    "manifest.timeline_start_seconds",
+  );
+  const manifestTimelineEndSeconds = requireFiniteNumber(
+    payload.timeline_end_seconds,
+    "manifest.timeline_end_seconds",
+  );
+  if (
+    manifestTimelineStartSeconds !== source.timelineStartSeconds ||
+    manifestTimelineEndSeconds !== source.timelineEndSeconds ||
+    manifestTimelineEndSeconds <= manifestTimelineStartSeconds
+  ) {
+    throw new ObservationSessionContractError(
+      "Временной диапазон manifest не совпадает с launch descriptor медиаканала.",
+    );
+  }
+  let previousEnd = Number.NEGATIVE_INFINITY;
+  let declaredBytes = 0;
+  const epochs = payload.epochs.map((entry, index): ObservationRecordedMediaEpoch => {
+    if (!isRecord(entry)) {
+      throw new ObservationSessionContractError(`Codec epoch ${index} должен быть объектом.`);
+    }
+    assertExactKeys(entry, RECORDED_MEDIA_EPOCH_KEYS, `Codec epoch ${index}`);
+    const ordinal = requireFiniteNumber(entry.ordinal, `epochs[${index}].ordinal`, {
+      minimum: 1,
+      maximum: 1_000,
+      integer: true,
+    });
+    if (ordinal !== index + 1) {
+      throw new ObservationSessionContractError("Codec epoch имеет непоследовательный ordinal.");
+    }
+    const timelineStartSeconds = requireFiniteNumber(
+      entry.timeline_start_seconds,
+      `epochs[${index}].timeline_start_seconds`,
+    );
+    const timelineEndSeconds = requireFiniteNumber(
+      entry.timeline_end_seconds,
+      `epochs[${index}].timeline_end_seconds`,
+    );
+    if (
+      timelineEndSeconds <= timelineStartSeconds ||
+      timelineStartSeconds < previousEnd ||
+      timelineStartSeconds < source.timelineStartSeconds ||
+      timelineEndSeconds > source.timelineEndSeconds
+    ) {
+      throw new ObservationSessionContractError("Codec epoch нарушает порядок временной шкалы.");
+    }
+    previousEnd = timelineEndSeconds;
+    const mediaType = requireString(entry.media_type, `epochs[${index}].media_type`, 128);
+    if (!SAFE_MP4_MEDIA_TYPE.test(mediaType)) {
+      throw new ObservationSessionContractError("Codec epoch содержит небезопасный media type.");
+    }
+    const initUrl = requireString(entry.init_url, `epochs[${index}].init_url`, 512);
+    const segmentUrlPrefix = requireString(
+      entry.segment_url_prefix,
+      `epochs[${index}].segment_url_prefix`,
+      512,
+    );
+    const expectedEpochBase = `${manifestBase}/epochs/${ordinal}`;
+    if (
+      initUrl !== `${expectedEpochBase}/init.mp4` ||
+      segmentUrlPrefix !== `${expectedEpochBase}/segments/` ||
+      initUrl.includes("..") ||
+      segmentUrlPrefix.includes("..")
+    ) {
+      throw new ObservationSessionContractError("Codec epoch содержит небезопасный API URL.");
+    }
+    const initByteLength = requireFiniteNumber(
+      entry.init_byte_length,
+      `epochs[${index}].init_byte_length`,
+      { minimum: 1, maximum: MAX_RECORDED_INIT_BYTES, integer: true },
+    );
+    if (typeof entry.init_sha256 !== "string" || !SHA256.test(entry.init_sha256)) {
+      throw new ObservationSessionContractError("Codec epoch не содержит SHA-256 init-сегмента.");
+    }
+    const segmentCount = requireFiniteNumber(
+      entry.segment_count,
+      `epochs[${index}].segment_count`,
+      { minimum: 1, maximum: 500_000, integer: true },
+    );
+    if (!Array.isArray(entry.segments) || entry.segments.length !== segmentCount) {
+      throw new ObservationSessionContractError(
+        "Codec epoch содержит неполный список канонических сегментов.",
+      );
+    }
+    const segments = entry.segments.map((segment, segmentIndex): ObservationRecordedMediaSegment => {
+      if (!isRecord(segment)) {
+        throw new ObservationSessionContractError(
+          `Сегмент epochs[${index}].segments[${segmentIndex}] должен быть объектом.`,
+        );
+      }
+      assertExactKeys(
+        segment,
+        RECORDED_MEDIA_SEGMENT_KEYS,
+        `Сегмент epochs[${index}].segments[${segmentIndex}]`,
+      );
+      const sequence = requireFiniteNumber(
+        segment.sequence,
+        `epochs[${index}].segments[${segmentIndex}].sequence`,
+        { minimum: 1, maximum: 500_000, integer: true },
+      );
+      if (sequence !== segmentIndex + 1) {
+        throw new ObservationSessionContractError(
+          "Codec epoch содержит непоследовательный сегмент.",
+        );
+      }
+      const url = requireString(
+        segment.url,
+        `epochs[${index}].segments[${segmentIndex}].url`,
+        512,
+      );
+      if (url !== `${segmentUrlPrefix}${sequence}.m4s` || url.includes("..")) {
+        throw new ObservationSessionContractError(
+          "Codec epoch содержит небезопасный URL сегмента.",
+        );
+      }
+      const byteLength = requireFiniteNumber(
+        segment.byte_length,
+        `epochs[${index}].segments[${segmentIndex}].byte_length`,
+        { minimum: 1, maximum: MAX_RECORDED_SEGMENT_BYTES, integer: true },
+      );
+      if (typeof segment.sha256 !== "string" || !SHA256.test(segment.sha256)) {
+        throw new ObservationSessionContractError(
+          "Codec epoch содержит сегмент без SHA-256.",
+        );
+      }
+      declaredBytes += byteLength;
+      return { sequence, url, byteLength, sha256: segment.sha256 };
+    });
+    declaredBytes += initByteLength;
+    if (declaredBytes > MAX_RECORDED_MEDIA_SOURCE_BYTES) {
+      throw new ObservationSessionContractError(
+        "Записанный медиаканал превышает безопасный лимит браузера.",
+      );
+    }
+    return {
+      ordinal,
+      timelineStartSeconds,
+      timelineEndSeconds,
+      mediaType,
+      initUrl,
+      initByteLength,
+      initSha256: entry.init_sha256,
+      segmentCount,
+      segmentUrlPrefix,
+      segments,
+    };
+  });
+  if (declaredBytes !== manifestByteLength) {
+    throw new ObservationSessionContractError(
+      "Сумма init- и media-сегментов не совпадает с размером immutable manifest.",
+    );
+  }
+  if (
+    epochs[0]?.timelineStartSeconds !== manifestTimelineStartSeconds ||
+    epochs[epochs.length - 1]?.timelineEndSeconds !== manifestTimelineEndSeconds
+  ) {
+    throw new ObservationSessionContractError(
+      "Codec epochs не покрывают граничные точки immutable manifest.",
+    );
+  }
+  return {
+    sourceId: source.id,
+    generationSha256: payload.generation_sha256,
+    byteLength: manifestByteLength,
+    timelineStartSeconds: manifestTimelineStartSeconds,
+    timelineEndSeconds: manifestTimelineEndSeconds,
+    synchronization: "host-arrival-best-effort",
+    epochs,
+  };
+}
+
+export async function fetchObservationRecordedMediaManifest(
+  source: ObservationRecordedMediaSource,
+  {
+    signal,
+    fetcher = globalThis.fetch,
+    expectedGenerationSha256,
+  }: {
+    signal?: AbortSignal;
+    fetcher?: ObservationSessionFetch;
+    expectedGenerationSha256?: string;
+  } = {},
+): Promise<ObservationRecordedMediaManifest> {
+  const boundGenerationSha256 = expectedGenerationSha256 ?? source.manifestGenerationSha256;
+  if (
+    !SHA256.test(boundGenerationSha256) ||
+    boundGenerationSha256 !== source.manifestGenerationSha256
+  ) {
+    throw new ObservationSessionContractError(
+      "Ожидаемая generation записанного видео имеет некорректный SHA-256.",
+    );
+  }
+  let response: Response;
+  try {
+    response = await fetcher(source.manifestUrl, {
+      method: "GET",
+      cache: "no-store",
+      headers: {
+        Accept: "application/json",
+        "If-Match": `"sha256:${boundGenerationSha256}"`,
+      },
+      signal,
+    });
+  } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") throw error;
+    throw new ObservationSessionApiError("Не удалось загрузить manifest записанного видео.");
+  }
+  const body = await responseBody(response);
+  if (!response.ok) {
+    throw new ObservationSessionApiError(
+      apiErrorMessage(body, `Manifest видео вернул HTTP ${response.status}.`),
+      response.status,
+    );
+  }
+  const manifest = decodeObservationRecordedMediaManifest(body, source);
+  if (manifest.generationSha256 !== boundGenerationSha256) {
+    throw new ObservationSessionContractError(
+      "Manifest записанного видео был заменён во время загрузки.",
+    );
+  }
+  const expectedEtag = `"sha256:${manifest.generationSha256}"`;
+  if (response.headers.get("ETag") !== expectedEtag) {
+    throw new ObservationSessionContractError(
+      "Manifest записанного видео не привязан к immutable generation.",
+    );
+  }
+  return manifest;
+}
+
+async function responseBody(response: Response): Promise<unknown> {
+  const text = await response.text();
+  if (!text) return undefined;
+  try {
+    return JSON.parse(text) as unknown;
+  } catch {
+    return text;
+  }
+}
+
+function apiErrorMessage(body: unknown, fallback: string): string {
+  if (isRecord(body) && typeof body.detail === "string" && body.detail.trim()) {
+    return body.detail.trim();
+  }
+  if (typeof body === "string" && body.trim()) return body.trim();
+  return fallback;
+}
+
+function preparationEtag(preparationId: string): string {
+  if (!SAFE_ID.test(preparationId)) {
+    throw new ObservationSessionContractError("Preparation id нельзя использовать как ETag.");
+  }
+  return `"${preparationId}"`;
+}
+
+function requirePreparationEtag(
+  response: Response,
+  preparationId: string,
+  context: string,
+): void {
+  const expected = preparationEtag(preparationId);
+  const received = response.headers.get("ETag");
+  if (received !== expected) {
+    throw new ObservationSessionContractError(
+      `${context} не подтвердил актуальный preparation ETag.`,
+    );
+  }
+}
+
+export async function fetchObservationSessionCatalog({
+  signal,
+  limit,
+  fetcher = globalThis.fetch,
+}: {
+  signal?: AbortSignal;
+  limit?: number;
+  fetcher?: ObservationSessionFetch;
+} = {}): Promise<ObservationSessionCatalog> {
+  const query = Number.isInteger(limit) && Number(limit) >= 1 && Number(limit) <= 100
+    ? `?limit=${Number(limit)}`
+    : "";
+  let response: Response;
+  try {
+    response = await fetcher(`/api/v1/observation-sessions${query}`, {
+      method: "GET",
+      headers: { Accept: "application/json" },
+      signal,
+    });
+  } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") throw error;
+    throw new ObservationSessionApiError("Не удалось загрузить каталог сохранённых сессий.");
+  }
+  const body = await responseBody(response);
+  if (!response.ok) {
+    throw new ObservationSessionApiError(
+      apiErrorMessage(body, `Каталог сессий вернул HTTP ${response.status}.`),
+      response.status,
+    );
+  }
+  return decodeObservationSessionCatalog(body);
+}
+
+export async function replayObservationSession(
+  sessionId: string,
+  {
+    signal,
+    fetcher = globalThis.fetch,
+  }: { signal?: AbortSignal; fetcher?: ObservationSessionFetch } = {},
+): Promise<ObservationSessionReplayResponse> {
+  if (!SAFE_ID.test(sessionId)) {
+    throw new ObservationSessionContractError(
+      "Идентификатор запускаемой сессии имеет недопустимый формат.",
+    );
+  }
+  let response: Response;
+  try {
+    response = await fetcher(
+      `/api/v1/observation-sessions/${encodeURIComponent(sessionId)}/replay`,
+      {
+        method: "POST",
+        headers: { Accept: "application/json" },
+        signal,
+      },
+    );
+  } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") throw error;
+    throw new ObservationSessionApiError("Не удалось запустить повтор сохранённой сессии.");
+  }
+  const body = await responseBody(response);
+  if (response.status === 200) {
+    const launch = decodeObservationSessionReplay(body);
+    if (launch.sessionId !== sessionId) {
+      throw new ObservationSessionContractError(
+        "Сервер подготовил повтор другой сессии.",
+      );
+    }
+    return { kind: "ready", launch };
+  }
+  if (response.status === 202 || response.status === 409) {
+    const preparation = decodeObservationSessionPreparation(body, sessionId);
+    requirePreparationEtag(response, preparation.preparationId, "Запуск подготовки");
+    const terminal = preparation.state === "failed" || preparation.state === "cancelled";
+    if ((response.status === 409) !== terminal) {
+      throw new ObservationSessionContractError(
+        "HTTP-статус не соответствует состоянию подготовки записи.",
+      );
+    }
+    return { kind: "preparing", preparation };
+  }
+  if (!response.ok) {
+    throw new ObservationSessionApiError(
+      apiErrorMessage(body, `Запуск повтора вернул HTTP ${response.status}.`),
+      response.status,
+    );
+  }
+  throw new ObservationSessionContractError(
+    `Запуск повтора вернул неожиданный HTTP ${response.status}.`,
+  );
+}
+
+export async function fetchObservationSessionPreparation(
+  preparation: Pick<ObservationSessionPreparation, "sessionId" | "preparationId" | "statusUrl">,
+  {
+    signal,
+    fetcher = globalThis.fetch,
+  }: { signal?: AbortSignal; fetcher?: ObservationSessionFetch } = {},
+): Promise<ObservationSessionReplayResponse> {
+  const expectedUrl =
+    `/api/v1/observation-sessions/${encodeURIComponent(preparation.sessionId)}/recording-preparation`;
+  if (
+    !SAFE_ID.test(preparation.sessionId) ||
+    !SAFE_ID.test(preparation.preparationId) ||
+    preparation.statusUrl !== expectedUrl ||
+    !SAFE_PREPARATION_URL.test(preparation.statusUrl)
+  ) {
+    throw new ObservationSessionContractError("Нельзя опросить небезопасный URL подготовки.");
+  }
+  let response: Response;
+  try {
+    response = await fetcher(preparation.statusUrl, {
+      method: "GET",
+      headers: {
+        Accept: "application/json",
+        "If-Match": preparationEtag(preparation.preparationId),
+      },
+      signal,
+    });
+  } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") throw error;
+    throw new ObservationSessionApiError("Не удалось проверить подготовку записи.");
+  }
+  const body = await responseBody(response);
+  if (response.status === 200) {
+    requirePreparationEtag(response, preparation.preparationId, "Готовая запись");
+    const launch = decodeObservationSessionReplay(body);
+    if (launch.sessionId !== preparation.sessionId) {
+      throw new ObservationSessionContractError("Подготовлен повтор другой сессии.");
+    }
+    return { kind: "ready", launch };
+  }
+  if (response.status === 202 || response.status === 409) {
+    const next = decodeObservationSessionPreparation(body, preparation.sessionId);
+    requirePreparationEtag(response, preparation.preparationId, "Статус подготовки");
+    if (
+      next.preparationId !== preparation.preparationId ||
+      next.statusUrl !== preparation.statusUrl
+    ) {
+      throw new ObservationSessionContractError("Сервер подменил идентификатор подготовки.");
+    }
+    const terminal = next.state === "failed" || next.state === "cancelled";
+    if ((response.status === 409) !== terminal) {
+      throw new ObservationSessionContractError(
+        "HTTP-статус не соответствует состоянию подготовки записи.",
+      );
+    }
+    return { kind: "preparing", preparation: next };
+  }
+  throw new ObservationSessionApiError(
+    apiErrorMessage(body, `Проверка подготовки вернула HTTP ${response.status}.`),
+    response.status,
+  );
+}
+
+export async function cancelObservationSessionPreparation(
+  preparation: Pick<ObservationSessionPreparation, "sessionId" | "preparationId" | "statusUrl">,
+  {
+    signal,
+    fetcher = globalThis.fetch,
+  }: { signal?: AbortSignal; fetcher?: ObservationSessionFetch } = {},
+): Promise<ObservationSessionPreparation | null> {
+  const expectedUrl =
+    `/api/v1/observation-sessions/${encodeURIComponent(preparation.sessionId)}/recording-preparation`;
+  if (
+    !SAFE_ID.test(preparation.sessionId) ||
+    !SAFE_ID.test(preparation.preparationId) ||
+    preparation.statusUrl !== expectedUrl ||
+    !SAFE_PREPARATION_URL.test(preparation.statusUrl)
+  ) {
+    throw new ObservationSessionContractError("Нельзя отменить небезопасную подготовку.");
+  }
+  let response: Response;
+  try {
+    response = await fetcher(preparation.statusUrl, {
+      method: "DELETE",
+      headers: {
+        Accept: "application/json",
+        "If-Match": preparationEtag(preparation.preparationId),
+      },
+      signal,
+    });
+  } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") throw error;
+    throw new ObservationSessionApiError("Не удалось отменить подготовку записи.");
+  }
+  if (response.status === 204) return null;
+  const body = await responseBody(response);
+  if (response.status === 200 || response.status === 202 || response.status === 409) {
+    const next = decodeObservationSessionPreparation(body, preparation.sessionId);
+    requirePreparationEtag(response, preparation.preparationId, "Отмена подготовки");
+    if (
+      next.preparationId !== preparation.preparationId ||
+      next.statusUrl !== preparation.statusUrl
+    ) {
+      throw new ObservationSessionContractError("Сервер подменил отменяемую подготовку.");
+    }
+    return next;
+  }
+  throw new ObservationSessionApiError(
+    apiErrorMessage(body, `Отмена подготовки вернула HTTP ${response.status}.`),
+    response.status,
+  );
+}
diff --git a/apps/control-station/src/core/observation/useObservationLayout.ts b/apps/control-station/src/core/observation/useObservationLayout.ts
index 45834f8..d82c256 100644
--- a/apps/control-station/src/core/observation/useObservationLayout.ts
+++ b/apps/control-station/src/core/observation/useObservationLayout.ts
@@ -6,12 +6,25 @@ import {
   openObservationSource,
   shouldRestartObservationSource,
 } from "./layoutPolicy";
+import {
+  normalizeObservationWindowRect,
+  projectObservationLayoutSnapshot,
+  validateObservationLayoutSnapshot,
+  validateObservationViewportSize,
+  type ObservationLayoutSnapshot,
+  type ObservationViewportSize,
+  type ObservationWindowRect,
+} from "./workspaceLayout";
 
-export interface ObservationWindowRect {
-  x: number;
-  y: number;
-  width: number;
-  height: number;
+export type { ObservationWindowRect } from "./workspaceLayout";
+
+export type ObservationLayoutPresentationMode = "preserve" | "reset";
+
+export function observationPresentationSourceAfterLayoutApply(
+  currentSourceId: string | null,
+  mode: ObservationLayoutPresentationMode,
+): string | null {
+  return mode === "preserve" ? currentSourceId : null;
 }
 
 export interface ObservationLayoutController {
@@ -20,6 +33,7 @@ export interface ObservationLayoutController {
   activeFloatingSourceId: string | null;
   maximizedFloatingSourceId: string | null;
   windowRects: Readonly<Record<string, ObservationWindowRect>>;
+  viewportSize: ObservationViewportSize | null;
   pendingSourceIds: ReadonlySet<string>;
   toggleSource: (sourceId: string) => Promise<boolean>;
   hideSource: (sourceId: string) => Promise<boolean>;
@@ -27,6 +41,9 @@ export interface ObservationLayoutController {
   activateFloatingSource: (sourceId: string) => void;
   setFloatingMaximized: (sourceId: string, maximized: boolean) => void;
   setWindowRect: (sourceId: string, rect: ObservationWindowRect) => void;
+  setViewportSize: (size: ObservationViewportSize) => void;
+  snapshot: () => ObservationLayoutSnapshot | null;
+  restore: (snapshot: ObservationLayoutSnapshot) => void;
 }
 
 function canOpenByDefault(source: ObservationSourceDescriptor): boolean {
@@ -50,6 +67,17 @@ function catalogIdentity(sources: readonly ObservationSourceDescriptor[]): strin
     .join("|");
 }
 
+function cloneSnapshot(snapshot: ObservationLayoutSnapshot): ObservationLayoutSnapshot {
+  return {
+    visibleSourceIds: [...snapshot.visibleSourceIds],
+    activeFloatingSourceId: snapshot.activeFloatingSourceId,
+    windowRects: Object.fromEntries(
+      Object.entries(snapshot.windowRects).map(([sourceId, rect]) => [sourceId, { ...rect }]),
+    ),
+    viewportSize: { ...snapshot.viewportSize },
+  };
+}
+
 export function useObservationLayout(
   sources: readonly ObservationSourceDescriptor[],
   setSourceActive?: (sourceId: string, active: boolean) => Promise<boolean>,
@@ -58,45 +86,151 @@ export function useObservationLayout(
   const visibleIdsRef = useRef<string[]>([]);
   const [pendingIds, setPendingIds] = useState<string[]>([]);
   const [focusedSourceId, setFocusedSourceIdState] = useState<string | null>(null);
-  const [activeFloatingSourceId, setActiveFloatingSourceId] = useState<string | null>(null);
+  const [activeFloatingSourceId, setActiveFloatingSourceIdState] = useState<string | null>(null);
+  const activeFloatingSourceIdRef = useRef<string | null>(null);
   const [maximizedFloatingSourceId, setMaximizedFloatingSourceId] = useState<string | null>(null);
-  const [windowRects, setWindowRects] = useState<Record<string, ObservationWindowRect>>({});
+  const [windowRects, setWindowRectsState] = useState<Record<string, ObservationWindowRect>>({});
+  const windowRectsRef = useRef<Record<string, ObservationWindowRect>>({});
+  const [viewportSize, setViewportSizeState] = useState<ObservationViewportSize | null>(null);
+  const viewportSizeRef = useRef<ObservationViewportSize | null>(null);
+  const desiredSnapshotRef = useRef<ObservationLayoutSnapshot | null>(null);
+  const restoredLayoutAuthorityRef = useRef(false);
   const initializedCatalog = useRef<string | null>(null);
   const sourceIdList = sources.map((source) => source.id).sort();
   const sourceIdsIdentity = sourceIdList.join("\u0000");
   const sourceIds = useMemo(() => new Set(sourceIdList), [sourceIdsIdentity]);
+  const sourceIdsRef = useRef<ReadonlySet<string>>(sourceIds);
+  sourceIdsRef.current = sourceIds;
+  const sourcesRef = useRef<readonly ObservationSourceDescriptor[]>(sources);
+  sourcesRef.current = sources;
   const identity = catalogIdentity(sources);
 
-  const commitVisibleIds = useCallback((next: string[]) => {
-    visibleIdsRef.current = next;
-    setVisibleIds(next);
+  const commitVisibleIds = useCallback((next: readonly string[]) => {
+    const unique = [...new Set(next)];
+    visibleIdsRef.current = unique;
+    setVisibleIds(unique);
   }, []);
 
-  const clearPresentation = useCallback((removedIds: readonly string[]) => {
+  const commitActiveFloatingSourceId = useCallback((next: string | null) => {
+    activeFloatingSourceIdRef.current = next;
+    setActiveFloatingSourceIdState(next);
+  }, []);
+
+  const commitWindowRects = useCallback((next: Record<string, ObservationWindowRect>) => {
+    windowRectsRef.current = next;
+    setWindowRectsState(next);
+  }, []);
+
+  const persistLiveLayout = useCallback(() => {
+    const currentViewport = viewportSizeRef.current;
+    if (!currentViewport) return;
+    const currentKnownIds = sourceIdsRef.current;
+    const previous = desiredSnapshotRef.current;
+    const unknownVisibleIds = previous?.visibleSourceIds.filter(
+      (sourceId) => !currentKnownIds.has(sourceId),
+    ) ?? [];
+    const visibleSourceIds = [...new Set([...unknownVisibleIds, ...visibleIdsRef.current])];
+    const unknownRects = Object.entries(previous?.windowRects ?? {}).filter(
+      ([sourceId]) => !currentKnownIds.has(sourceId),
+    );
+    const knownRects = Object.entries(windowRectsRef.current).map(([sourceId, rect]) => [
+      sourceId,
+      normalizeObservationWindowRect(rect, currentViewport),
+    ] as const);
+    const previousActive = previous?.activeFloatingSourceId ?? null;
+    const activeFloatingSourceId = activeFloatingSourceIdRef.current ?? (
+      previousActive && !currentKnownIds.has(previousActive) ? previousActive : null
+    );
+    desiredSnapshotRef.current = validateObservationLayoutSnapshot({
+      visibleSourceIds,
+      activeFloatingSourceId: activeFloatingSourceId && visibleSourceIds.includes(activeFloatingSourceId)
+        ? activeFloatingSourceId
+        : null,
+      windowRects: Object.fromEntries([...unknownRects, ...knownRects]),
+      viewportSize: currentViewport,
+    });
+  }, []);
+
+  const applyDesiredSnapshot = useCallback((
+    snapshot: ObservationLayoutSnapshot,
+    presentationMode: ObservationLayoutPresentationMode,
+  ) => {
+    const targetViewport = viewportSizeRef.current ?? snapshot.viewportSize;
+    const projected = projectObservationLayoutSnapshot(
+      snapshot,
+      sourceIdsRef.current,
+      targetViewport,
+    );
+    let visibleSourceIds = [...projected.visibleSourceIds];
+    let activeFloatingSourceId = projected.activeFloatingSourceId;
+    if (visibleSourceIds.length === 0 && sourcesRef.current.length > 0) {
+      for (const source of sourcesRef.current.filter(canOpenByDefault)) {
+        visibleSourceIds = openObservationSource(
+          visibleSourceIds,
+          source.id,
+          sourcesRef.current,
+        ).visibleIds;
+      }
+      activeFloatingSourceId = sourcesRef.current.find(
+        (source) => visibleSourceIds.includes(source.id) && source.capabilities.overlay,
+      )?.id ?? null;
+    }
+    commitVisibleIds(visibleSourceIds);
+    commitActiveFloatingSourceId(activeFloatingSourceId);
+    commitWindowRects({ ...projected.windowRects });
+    setFocusedSourceIdState((current) =>
+      observationPresentationSourceAfterLayoutApply(current, presentationMode));
+    setMaximizedFloatingSourceId((current) =>
+      observationPresentationSourceAfterLayoutApply(current, presentationMode));
+  }, [commitActiveFloatingSourceId, commitVisibleIds, commitWindowRects]);
+
+  const clearPresentation = useCallback((removedIds: readonly string[], persist = true) => {
     if (!removedIds.length) return;
     const removed = new Set(removedIds);
     setFocusedSourceIdState((current) => current && removed.has(current) ? null : current);
-    setActiveFloatingSourceId((current) => current && removed.has(current) ? null : current);
+    if (
+      activeFloatingSourceIdRef.current &&
+      removed.has(activeFloatingSourceIdRef.current)
+    ) {
+      commitActiveFloatingSourceId(null);
+    }
     setMaximizedFloatingSourceId((current) => current && removed.has(current) ? null : current);
-  }, []);
+    if (persist) persistLiveLayout();
+  }, [commitActiveFloatingSourceId, persistLiveLayout]);
 
   useEffect(() => {
+    const desired = desiredSnapshotRef.current;
+    if (desired) {
+      applyDesiredSnapshot(desired, "reset");
+      return;
+    }
     const currentVisible = visibleIdsRef.current;
     const nextVisible = currentVisible.filter((sourceId) => sourceIds.has(sourceId));
     if (nextVisible.length !== currentVisible.length) commitVisibleIds(nextVisible);
     setFocusedSourceIdState((current) => current && sourceIds.has(current) ? current : null);
-    setActiveFloatingSourceId((current) => current && sourceIds.has(current) ? current : null);
+    if (activeFloatingSourceIdRef.current && !sourceIds.has(activeFloatingSourceIdRef.current)) {
+      commitActiveFloatingSourceId(null);
+    }
     setMaximizedFloatingSourceId((current) => current && sourceIds.has(current) ? current : null);
-    setWindowRects((current) => {
-      const entries = Object.entries(current);
-      const nextEntries = entries.filter(([sourceId]) => sourceIds.has(sourceId));
-      return nextEntries.length === entries.length ? current : Object.fromEntries(nextEntries);
-    });
-  }, [commitVisibleIds, sourceIds]);
+    const entries = Object.entries(windowRectsRef.current);
+    const nextEntries = entries.filter(([sourceId]) => sourceIds.has(sourceId));
+    if (nextEntries.length !== entries.length) commitWindowRects(Object.fromEntries(nextEntries));
+  }, [
+    applyDesiredSnapshot,
+    commitActiveFloatingSourceId,
+    commitVisibleIds,
+    commitWindowRects,
+    sourceIds,
+  ]);
 
   useEffect(() => {
     if (!identity) {
-      initializedCatalog.current = null;
+      if (!desiredSnapshotRef.current) initializedCatalog.current = null;
+      return;
+    }
+    const desired = desiredSnapshotRef.current;
+    if (desired) {
+      initializedCatalog.current = identity;
       return;
     }
     if (initializedCatalog.current === identity) return;
@@ -109,8 +243,16 @@ export function useObservationLayout(
     const firstFloating = sources.find(
       (source) => canOpenByDefault(source) && source.capabilities.overlay,
     );
-    setActiveFloatingSourceId(firstFloating?.id ?? null);
-  }, [commitVisibleIds, identity, sources]);
+    commitActiveFloatingSourceId(firstFloating?.id ?? null);
+    persistLiveLayout();
+  }, [
+    applyDesiredSnapshot,
+    commitActiveFloatingSourceId,
+    commitVisibleIds,
+    identity,
+    persistLiveLayout,
+    sources,
+  ]);
 
   const selectedDeliveryIdentity = sources
     .filter((source) => source.capabilities.defaultVisible && source.activation?.selected && source.delivery)
@@ -124,6 +266,7 @@ export function useObservationLayout(
     .join("|");
 
   useEffect(() => {
+    if (restoredLayoutAuthorityRef.current) return;
     const selected = sources.filter(
       (source) => source.capabilities.defaultVisible && source.activation?.selected && source.delivery,
     );
@@ -135,8 +278,9 @@ export function useObservationLayout(
       change.removedIds.forEach((sourceId) => removed.add(sourceId));
     }
     commitVisibleIds(change.visibleIds);
-    clearPresentation([...removed]);
-  }, [clearPresentation, commitVisibleIds, selectedDeliveryIdentity]);
+    clearPresentation([...removed], false);
+    persistLiveLayout();
+  }, [clearPresentation, commitVisibleIds, persistLiveLayout, selectedDeliveryIdentity]);
 
   const markPending = useCallback((source: ObservationSourceDescriptor, pending: boolean) => {
     const groupId = source.activation?.groupId;
@@ -160,11 +304,13 @@ export function useObservationLayout(
         markPending(source, false);
       }
     }
+    restoredLayoutAuthorityRef.current = false;
     const change = closeObservationSource(visibleIdsRef.current, sourceId);
     commitVisibleIds(change.visibleIds);
-    clearPresentation(change.removedIds);
+    clearPresentation(change.removedIds, false);
+    persistLiveLayout();
     return true;
-  }, [clearPresentation, commitVisibleIds, markPending, setSourceActive, sources]);
+  }, [clearPresentation, commitVisibleIds, markPending, persistLiveLayout, setSourceActive, sources]);
 
   const toggleSource = useCallback(async (sourceId: string) => {
     const source = sources.find((candidate) => candidate.id === sourceId);
@@ -180,30 +326,95 @@ export function useObservationLayout(
         markPending(source, false);
       }
     }
+    restoredLayoutAuthorityRef.current = false;
     const change = openObservationSource(visibleIdsRef.current, sourceId, sources);
     commitVisibleIds(change.visibleIds);
-    clearPresentation(change.removedIds);
-    setActiveFloatingSourceId(sourceId);
+    clearPresentation(change.removedIds, false);
+    commitActiveFloatingSourceId(sourceId);
+    persistLiveLayout();
     return true;
-  }, [clearPresentation, commitVisibleIds, hideSource, markPending, setSourceActive, sources]);
+  }, [
+    clearPresentation,
+    commitActiveFloatingSourceId,
+    commitVisibleIds,
+    hideSource,
+    markPending,
+    persistLiveLayout,
+    setSourceActive,
+    sources,
+  ]);
 
   const setFocusedSourceId = useCallback((sourceId: string | null) => {
     setFocusedSourceIdState(sourceId);
-    if (sourceId) setActiveFloatingSourceId(sourceId);
-  }, []);
+    if (sourceId) {
+      commitActiveFloatingSourceId(sourceId);
+      persistLiveLayout();
+    }
+  }, [commitActiveFloatingSourceId, persistLiveLayout]);
 
   const activateFloatingSource = useCallback((sourceId: string) => {
-    setActiveFloatingSourceId(sourceId);
-  }, []);
+    commitActiveFloatingSourceId(sourceId);
+    persistLiveLayout();
+  }, [commitActiveFloatingSourceId, persistLiveLayout]);
 
   const setFloatingMaximized = useCallback((sourceId: string, maximized: boolean) => {
     setMaximizedFloatingSourceId(maximized ? sourceId : null);
-    if (maximized) setActiveFloatingSourceId(sourceId);
-  }, []);
+    if (maximized) {
+      commitActiveFloatingSourceId(sourceId);
+      persistLiveLayout();
+    }
+  }, [commitActiveFloatingSourceId, persistLiveLayout]);
 
   const setWindowRect = useCallback((sourceId: string, rect: ObservationWindowRect) => {
-    setWindowRects((current) => ({ ...current, [sourceId]: rect }));
-  }, []);
+    if (
+      !Object.values(rect).every((value) => Number.isFinite(value)) ||
+      rect.width <= 0 ||
+      rect.height <= 0
+    ) {
+      return;
+    }
+    const currentViewport = viewportSizeRef.current;
+    if (currentViewport) normalizeObservationWindowRect(rect, currentViewport);
+    commitWindowRects({ ...windowRectsRef.current, [sourceId]: { ...rect } });
+    persistLiveLayout();
+  }, [commitWindowRects, persistLiveLayout]);
+
+  const setViewportSize = useCallback((size: ObservationViewportSize) => {
+    const next = validateObservationViewportSize(size);
+    const current = viewportSizeRef.current;
+    if (current && current.width === next.width && current.height === next.height) return;
+    viewportSizeRef.current = next;
+    setViewportSizeState(next);
+    const desired = desiredSnapshotRef.current;
+    if (desired) {
+      desiredSnapshotRef.current = { ...desired, viewportSize: next };
+      // Entering fullscreen changes the shell geometry, which triggers this
+      // ResizeObserver path. Reproject persistent window rectangles without
+      // clearing the transient fullscreen/focus state that caused the resize.
+      applyDesiredSnapshot(desiredSnapshotRef.current, "preserve");
+    } else if (initializedCatalog.current) {
+      persistLiveLayout();
+    }
+  }, [applyDesiredSnapshot, persistLiveLayout]);
+
+  const snapshot = useCallback((): ObservationLayoutSnapshot | null => {
+    if (!viewportSizeRef.current) return null;
+    persistLiveLayout();
+    const desired = desiredSnapshotRef.current;
+    if (!desired) return null;
+    return cloneSnapshot(desired);
+  }, [persistLiveLayout]);
+
+  const restore = useCallback((saved: ObservationLayoutSnapshot) => {
+    const validated = validateObservationLayoutSnapshot(saved);
+    const currentViewport = viewportSizeRef.current;
+    desiredSnapshotRef.current = cloneSnapshot({
+      ...validated,
+      viewportSize: currentViewport ?? validated.viewportSize,
+    });
+    restoredLayoutAuthorityRef.current = true;
+    applyDesiredSnapshot(desiredSnapshotRef.current, "reset");
+  }, [applyDesiredSnapshot]);
 
   const visibleSourceIds = useMemo(() => new Set(visibleIds), [visibleIds]);
   const pendingSourceIds = useMemo(() => new Set(pendingIds), [pendingIds]);
@@ -214,6 +425,7 @@ export function useObservationLayout(
     activeFloatingSourceId,
     maximizedFloatingSourceId,
     windowRects,
+    viewportSize,
     pendingSourceIds,
     toggleSource,
     hideSource,
@@ -221,5 +433,8 @@ export function useObservationLayout(
     activateFloatingSource,
     setFloatingMaximized,
     setWindowRect,
+    setViewportSize,
+    snapshot,
+    restore,
   };
 }
diff --git a/apps/control-station/src/core/observation/useObservationSessions.ts b/apps/control-station/src/core/observation/useObservationSessions.ts
new file mode 100644
index 0000000..dacbcd8
--- /dev/null
+++ b/apps/control-station/src/core/observation/useObservationSessions.ts
@@ -0,0 +1,591 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+
+import {
+  decodeObservationSessionPreparation,
+  fetchObservationSessionCatalog,
+  fetchObservationSessionPreparation,
+  replayObservationSession,
+  type ObservationSessionFetch,
+  type ObservationSessionPreparation,
+  type ObservationSessionReplayLaunch,
+  type ObservationSessionSummary,
+} from "./sessionArchive";
+
+export type ObservationSessionsLoadState = "idle" | "loading" | "ready" | "error";
+export type ObservationReplayOutcome = "accepted" | "error" | "cancelled";
+export type ObservationPreparationPhase =
+  | "requesting"
+  | ObservationSessionPreparation["state"];
+
+export interface ObservationReplayProgress {
+  readonly sessionId: string;
+  readonly phase: ObservationPreparationPhase;
+  readonly progress: number | null;
+  readonly cancellable: boolean;
+}
+
+export interface ObservationSessionsController {
+  items: readonly ObservationSessionSummary[];
+  state: ObservationSessionsLoadState;
+  error: string | null;
+  replayingSessionId: string | null;
+  preparation: ObservationSessionPreparation | null;
+  replayProgress: ObservationReplayProgress | null;
+  failedSessionId: string | null;
+  refresh: () => Promise<boolean>;
+  replay: (sessionId: string) => Promise<boolean>;
+  retry: () => Promise<boolean>;
+}
+
+export interface ObservationReplayAttempt {
+  readonly signal: AbortSignal;
+  isCurrent: () => boolean;
+  finish: () => boolean;
+}
+
+export interface ObservationReplayCoordinator {
+  begin: () => ObservationReplayAttempt;
+  cancel: () => void;
+}
+
+export interface ObservationPreparationPollingOptions {
+  signal: AbortSignal;
+  fetcher?: ObservationSessionFetch;
+  onUpdate?: (preparation: ObservationSessionPreparation) => void;
+  requestTimeoutMs?: number;
+  heartbeatStallMs?: number;
+  maximumWaitMs?: number;
+  initialPollIntervalMs?: number;
+  maximumPollIntervalMs?: number;
+  now?: () => number;
+  sleep?: (milliseconds: number, signal: AbortSignal) => Promise<void>;
+}
+
+const PREPARATION_STORAGE_KEY = "missioncore.observation-session-preparation/v1";
+const DEFAULT_REQUEST_TIMEOUT_MS = 15_000;
+const DEFAULT_HEARTBEAT_STALL_MS = 45_000;
+const DEFAULT_MAXIMUM_WAIT_MS = 30 * 60_000;
+const DEFAULT_INITIAL_POLL_INTERVAL_MS = 750;
+const DEFAULT_MAXIMUM_POLL_INTERVAL_MS = 3_000;
+
+export class ObservationPreparationStalledError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "ObservationPreparationStalledError";
+  }
+}
+
+/** Latest selection wins, even if an obsolete server job finishes later. */
+export function createObservationReplayCoordinator(): ObservationReplayCoordinator {
+  let sequence = 0;
+  let active: AbortController | null = null;
+
+  return {
+    begin() {
+      active?.abort();
+      const controller = new AbortController();
+      const attemptSequence = ++sequence;
+      active = controller;
+      return {
+        signal: controller.signal,
+        isCurrent: () => (
+          !controller.signal.aborted &&
+          active === controller &&
+          sequence === attemptSequence
+        ),
+        finish: () => {
+          if (active !== controller || sequence !== attemptSequence) return false;
+          active = null;
+          return true;
+        },
+      };
+    },
+    cancel() {
+      sequence += 1;
+      active?.abort();
+      active = null;
+    },
+  };
+}
+
+function errorMessage(error: unknown): string {
+  return error instanceof Error && error.message.trim()
+    ? error.message
+    : "Операция с сохранёнными сессиями завершилась ошибкой.";
+}
+
+function isAbortError(error: unknown): boolean {
+  return error instanceof DOMException && error.name === "AbortError";
+}
+
+type PendingPreparationState = Exclude<
+  ObservationSessionPreparation["state"],
+  "failed" | "cancelled"
+>;
+
+function pendingPreparation(
+  preparation: ObservationSessionPreparation,
+): preparation is ObservationSessionPreparation & { state: PendingPreparationState } {
+  return preparation.state !== "failed" && preparation.state !== "cancelled";
+}
+
+const PREPARATION_PHASE_ORDER: Record<
+  PendingPreparationState,
+  number
+> = {
+  queued: 0,
+  validating: 1,
+  exporting: 2,
+  finalizing: 3,
+};
+
+function terminalPreparationError(preparation: ObservationSessionPreparation): Error {
+  if (preparation.error) return new Error(preparation.error);
+  return new Error(
+    preparation.state === "cancelled"
+      ? "Подготовка записи отменена."
+      : "Сервер не смог подготовить сохранённую сессию.",
+  );
+}
+
+function defaultSleep(milliseconds: number, signal: AbortSignal): Promise<void> {
+  return new Promise((resolve, reject) => {
+    if (signal.aborted) {
+      reject(new DOMException("cancelled", "AbortError"));
+      return;
+    }
+    const onAbort = () => {
+      globalThis.clearTimeout(timer);
+      reject(new DOMException("cancelled", "AbortError"));
+    };
+    const timer = globalThis.setTimeout(() => {
+      signal.removeEventListener("abort", onAbort);
+      resolve();
+    }, milliseconds);
+    signal.addEventListener("abort", onAbort, { once: true });
+  });
+}
+
+async function withRequestTimeout<T>(
+  signal: AbortSignal,
+  timeoutMs: number,
+  operation: (signal: AbortSignal) => Promise<T>,
+): Promise<T> {
+  if (signal.aborted) throw new DOMException("cancelled", "AbortError");
+  const controller = new AbortController();
+  let timedOut = false;
+  const forwardAbort = () => controller.abort();
+  signal.addEventListener("abort", forwardAbort, { once: true });
+  const timer = globalThis.setTimeout(() => {
+    timedOut = true;
+    controller.abort();
+  }, timeoutMs);
+  try {
+    return await operation(controller.signal);
+  } catch (error) {
+    if (timedOut && isAbortError(error)) {
+      throw new ObservationPreparationStalledError(
+        "Сервер слишком долго не отвечает. Подготовку можно повторить.",
+      );
+    }
+    throw error;
+  } finally {
+    globalThis.clearTimeout(timer);
+    signal.removeEventListener("abort", forwardAbort);
+  }
+}
+
+export async function waitForObservationReplayPreparation(
+  initial: ObservationSessionPreparation,
+  options: ObservationPreparationPollingOptions,
+): Promise<ObservationSessionReplayLaunch> {
+  if (!pendingPreparation(initial)) throw terminalPreparationError(initial);
+  const requestTimeoutMs = Math.max(100, options.requestTimeoutMs ?? DEFAULT_REQUEST_TIMEOUT_MS);
+  const heartbeatStallMs = Math.max(250, options.heartbeatStallMs ?? DEFAULT_HEARTBEAT_STALL_MS);
+  const maximumWaitMs = Math.max(heartbeatStallMs, options.maximumWaitMs ?? DEFAULT_MAXIMUM_WAIT_MS);
+  const initialInterval = Math.max(
+    50,
+    options.initialPollIntervalMs ?? DEFAULT_INITIAL_POLL_INTERVAL_MS,
+  );
+  const maximumInterval = Math.max(
+    initialInterval,
+    options.maximumPollIntervalMs ?? DEFAULT_MAXIMUM_POLL_INTERVAL_MS,
+  );
+  const now = options.now ?? Date.now;
+  const sleep = options.sleep ?? defaultSleep;
+  const startedAt = now();
+  let lastHeartbeatAt = startedAt;
+  let lastUpdatedAt = Date.parse(initial.updatedAtUtc);
+  let current: ObservationSessionPreparation = initial;
+  let interval = initialInterval;
+  options.onUpdate?.(current);
+
+  while (true) {
+    await sleep(interval, options.signal);
+    const response = await withRequestTimeout(
+      options.signal,
+      requestTimeoutMs,
+      (signal) => fetchObservationSessionPreparation(current, {
+        signal,
+        fetcher: options.fetcher,
+      }),
+    );
+    if (response.kind === "ready") return response.launch;
+
+    const next = response.preparation;
+    const nextUpdatedAt = Date.parse(next.updatedAtUtc);
+    if (nextUpdatedAt < lastUpdatedAt) {
+      throw new Error("Сервер вернул устаревшее состояние подготовки записи.");
+    }
+    if (nextUpdatedAt > lastUpdatedAt) {
+      lastUpdatedAt = nextUpdatedAt;
+      lastHeartbeatAt = now();
+    } else if (
+      next.state !== current.state ||
+      next.progress !== current.progress ||
+      next.cancellable !== current.cancellable
+    ) {
+      throw new Error("Сервер изменил подготовку без обновления heartbeat timestamp.");
+    }
+    if (pendingPreparation(next) && pendingPreparation(current)) {
+      if (PREPARATION_PHASE_ORDER[next.state] < PREPARATION_PHASE_ORDER[current.state]) {
+        throw new Error("Сервер вернул подготовку на уже завершённую фазу.");
+      }
+      if (
+        next.progress !== null &&
+        current.progress !== null &&
+        next.progress + Number.EPSILON < current.progress
+      ) {
+        throw new Error("Прогресс подготовки не может уменьшаться.");
+      }
+    }
+    current = next;
+    options.onUpdate?.(current);
+    if (!pendingPreparation(current)) throw terminalPreparationError(current);
+    if (current.state !== "queued" && now() - lastHeartbeatAt > heartbeatStallMs) {
+      throw new ObservationPreparationStalledError(
+        "Подготовка перестала обновляться. Текущая сцена сохранена; повторите запуск.",
+      );
+    }
+    if (now() - startedAt > maximumWaitMs) {
+      throw new ObservationPreparationStalledError(
+        "Подготовка превысила допустимое время. Текущая сцена сохранена; повторите запуск.",
+      );
+    }
+    interval = Math.min(maximumInterval, Math.round(interval * 1.35));
+  }
+}
+
+export async function resolveObservationSessionReplay(
+  sessionId: string,
+  options: ObservationPreparationPollingOptions,
+): Promise<ObservationSessionReplayLaunch> {
+  const response = await withRequestTimeout(
+    options.signal,
+    Math.max(100, options.requestTimeoutMs ?? DEFAULT_REQUEST_TIMEOUT_MS),
+    (signal) => replayObservationSession(sessionId, { signal, fetcher: options.fetcher }),
+  );
+  if (response.kind === "ready") return response.launch;
+  if (!pendingPreparation(response.preparation)) {
+    options.onUpdate?.(response.preparation);
+    throw terminalPreparationError(response.preparation);
+  }
+  return waitForObservationReplayPreparation(response.preparation, options);
+}
+
+function preparationStoragePayload(preparation: ObservationSessionPreparation): unknown {
+  return {
+    schema_version: "missioncore.observation-session-preparation/v1",
+    preparation: {
+      preparation_id: preparation.preparationId,
+      session_id: preparation.sessionId,
+      state: preparation.state,
+      progress: preparation.progress,
+      updated_at_utc: preparation.updatedAtUtc,
+      status_url: preparation.statusUrl,
+      cancellable: preparation.cancellable,
+      ...(preparation.state === "failed" || preparation.state === "cancelled"
+        ? { retryable: preparation.retryable, error: preparation.error }
+        : {}),
+    },
+  };
+}
+
+export function storeObservationReplayPreparation(
+  preparation: ObservationSessionPreparation,
+  storage: Storage = window.localStorage,
+): void {
+  if (!pendingPreparation(preparation)) {
+    storage.removeItem(PREPARATION_STORAGE_KEY);
+    return;
+  }
+  storage.setItem(PREPARATION_STORAGE_KEY, JSON.stringify(preparationStoragePayload(preparation)));
+}
+
+export function loadObservationReplayPreparation(
+  storage: Storage = window.localStorage,
+): ObservationSessionPreparation | null {
+  const serialized = storage.getItem(PREPARATION_STORAGE_KEY);
+  if (!serialized) return null;
+  try {
+    const parsed = JSON.parse(serialized) as unknown;
+    if (
+      typeof parsed !== "object" ||
+      parsed === null ||
+      !("preparation" in parsed) ||
+      typeof parsed.preparation !== "object" ||
+      parsed.preparation === null ||
+      !("session_id" in parsed.preparation) ||
+      typeof parsed.preparation.session_id !== "string"
+    ) {
+      throw new Error("invalid persisted preparation");
+    }
+    const preparation = decodeObservationSessionPreparation(
+      parsed,
+      parsed.preparation.session_id,
+    );
+    return pendingPreparation(preparation) ? preparation : null;
+  } catch {
+    storage.removeItem(PREPARATION_STORAGE_KEY);
+    return null;
+  }
+}
+
+export function clearObservationReplayPreparation(
+  storage: Storage = window.localStorage,
+): void {
+  storage.removeItem(PREPARATION_STORAGE_KEY);
+}
+
+export function useObservationSessions({
+  limit = 3,
+  onReplayBegin,
+  onReplayAccepted,
+  onReplaySettled,
+}: {
+  limit?: number;
+  /** Called only after the archive is ready, immediately before replacing the old viewer. */
+  onReplayBegin?: (
+    session: ObservationSessionSummary,
+    launch: ObservationSessionReplayLaunch,
+  ) => void | Promise<void>;
+  onReplayAccepted?: (
+    session: ObservationSessionSummary,
+    launch: ObservationSessionReplayLaunch,
+  ) => void | Promise<void>;
+  onReplaySettled?: (
+    session: ObservationSessionSummary,
+    outcome: ObservationReplayOutcome,
+  ) => void | Promise<void>;
+} = {}): ObservationSessionsController {
+  const [items, setItems] = useState<ObservationSessionSummary[]>([]);
+  const [state, setState] = useState<ObservationSessionsLoadState>("idle");
+  const [error, setError] = useState<string | null>(null);
+  const [replayingSessionId, setReplayingSessionId] = useState<string | null>(null);
+  const [preparation, setPreparation] = useState<ObservationSessionPreparation | null>(null);
+  const [replayProgress, setReplayProgress] = useState<ObservationReplayProgress | null>(null);
+  const [failedSessionId, setFailedSessionId] = useState<string | null>(null);
+  const mounted = useRef(true);
+  const catalogSequence = useRef(0);
+  const reattachStarted = useRef(false);
+  const preparationPollSequence = useRef(0);
+  const replayCoordinator = useRef<ObservationReplayCoordinator | null>(null);
+  if (replayCoordinator.current === null) {
+    replayCoordinator.current = createObservationReplayCoordinator();
+  }
+  const safeLimit = Number.isFinite(limit) ? Math.max(0, Math.floor(limit)) : 3;
+
+  const refresh = useCallback(async () => {
+    const sequence = ++catalogSequence.current;
+    setState("loading");
+    setError(null);
+    try {
+      const catalog = await fetchObservationSessionCatalog({ limit: safeLimit });
+      if (!mounted.current || sequence !== catalogSequence.current) return false;
+      setItems(catalog.items.slice(0, safeLimit));
+      setState("ready");
+      return true;
+    } catch (loadError) {
+      if (!mounted.current || sequence !== catalogSequence.current) return false;
+      setState("error");
+      setError(errorMessage(loadError));
+      return false;
+    }
+  }, [safeLimit]);
+
+  useEffect(() => {
+    mounted.current = true;
+    void refresh();
+    return () => {
+      mounted.current = false;
+      catalogSequence.current += 1;
+      replayCoordinator.current?.cancel();
+    };
+  }, [refresh]);
+
+  const catalogHasActivePreparation = items.some((item) => (
+    item.preparation !== null &&
+    ["queued", "validating", "exporting", "finalizing"].includes(item.preparation.state)
+  ));
+
+  useEffect(() => {
+    if (state !== "ready" || !catalogHasActivePreparation) return;
+    const sequence = ++preparationPollSequence.current;
+    const controller = new AbortController();
+    const timer = window.setTimeout(async () => {
+      try {
+        const catalog = await fetchObservationSessionCatalog({
+          limit: safeLimit,
+          signal: controller.signal,
+        });
+        if (
+          mounted.current &&
+          !controller.signal.aborted &&
+          sequence === preparationPollSequence.current
+        ) {
+          setItems(catalog.items.slice(0, safeLimit));
+        }
+      } catch (pollError) {
+        if (
+          mounted.current &&
+          !controller.signal.aborted &&
+          sequence === preparationPollSequence.current
+        ) {
+          setError(errorMessage(pollError));
+        }
+      }
+    }, 1_500);
+    return () => {
+      preparationPollSequence.current += 1;
+      window.clearTimeout(timer);
+      controller.abort();
+    };
+  }, [catalogHasActivePreparation, items, safeLimit, state]);
+
+  const executeReplay = useCallback(async (
+    session: ObservationSessionSummary,
+    resumedPreparation?: ObservationSessionPreparation,
+  ) => {
+    const attempt = replayCoordinator.current!.begin();
+    setReplayingSessionId(session.id);
+    setFailedSessionId(null);
+    setError(null);
+    setReplayProgress({
+      sessionId: session.id,
+      phase: resumedPreparation?.state ?? "requesting",
+      progress: resumedPreparation?.progress ?? null,
+      cancellable: resumedPreparation?.cancellable ?? false,
+    });
+    let outcome: ObservationReplayOutcome = "cancelled";
+    try {
+      const onUpdate = (next: ObservationSessionPreparation) => {
+        if (!mounted.current || !attempt.isCurrent()) return;
+        setPreparation(next);
+        setReplayProgress({
+          sessionId: next.sessionId,
+          phase: next.state,
+          progress: next.progress,
+          cancellable: next.cancellable,
+        });
+        try {
+          storeObservationReplayPreparation(next);
+        } catch {
+          // Private browsing/storage quota must not break replay preparation.
+        }
+      };
+      const launch = resumedPreparation
+        ? await waitForObservationReplayPreparation(resumedPreparation, {
+            signal: attempt.signal,
+            onUpdate,
+          })
+        : await resolveObservationSessionReplay(session.id, {
+            signal: attempt.signal,
+            onUpdate,
+          });
+      if (!mounted.current || !attempt.isCurrent()) return false;
+
+      // The current scene stays mounted throughout preparation. Only now that
+      // the launch descriptor exists do we release the previous viewer.
+      await onReplayBegin?.(session, launch);
+      if (!mounted.current || !attempt.isCurrent()) return false;
+      await onReplayAccepted?.(session, launch);
+      if (!mounted.current || !attempt.isCurrent()) return false;
+      outcome = "accepted";
+      try {
+        clearObservationReplayPreparation();
+      } catch {
+        // Storage is optional; an accepted replay must not turn into an error.
+      }
+      setPreparation(null);
+      setReplayProgress(null);
+      return true;
+    } catch (replayError) {
+      const aborted = isAbortError(replayError);
+      outcome = aborted ? "cancelled" : "error";
+      if (mounted.current && attempt.isCurrent() && !aborted) {
+        setError(errorMessage(replayError));
+        setFailedSessionId(session.id);
+        setReplayProgress(null);
+        try {
+          clearObservationReplayPreparation();
+        } catch {
+          // Storage is optional for the current browser lifetime.
+        }
+      }
+      return false;
+    } finally {
+      const current = attempt.finish();
+      if (mounted.current && current) {
+        setReplayingSessionId(null);
+        await onReplaySettled?.(session, outcome);
+      }
+    }
+  }, [onReplayAccepted, onReplayBegin, onReplaySettled]);
+
+  const replay = useCallback(async (sessionId: string) => {
+    const session = items.find((candidate) => candidate.id === sessionId);
+    if (!session || !session.replayable) return false;
+    reattachStarted.current = true;
+    return executeReplay(session);
+  }, [executeReplay, items]);
+
+  useEffect(() => {
+    if (state !== "ready" || reattachStarted.current) return;
+    reattachStarted.current = true;
+    let stored: ObservationSessionPreparation | null = null;
+    try {
+      stored = loadObservationReplayPreparation();
+    } catch {
+      stored = null;
+    }
+    if (!stored) return;
+    const session = items.find((candidate) => candidate.id === stored?.sessionId);
+    if (!session?.replayable) {
+      try {
+        clearObservationReplayPreparation();
+      } catch {
+        // Storage may be unavailable in hardened browser profiles.
+      }
+      return;
+    }
+    void executeReplay(session, stored);
+  }, [executeReplay, items, state]);
+
+  const retry = useCallback(async () => {
+    if (!failedSessionId) return false;
+    return replay(failedSessionId);
+  }, [failedSessionId, replay]);
+
+  return {
+    items,
+    state,
+    error,
+    replayingSessionId,
+    preparation,
+    replayProgress,
+    failedSessionId,
+    refresh,
+    replay,
+    retry,
+  };
+}
diff --git a/apps/control-station/src/core/observation/useRecordedSessionAdmission.ts b/apps/control-station/src/core/observation/useRecordedSessionAdmission.ts
new file mode 100644
index 0000000..a82aee6
--- /dev/null
+++ b/apps/control-station/src/core/observation/useRecordedSessionAdmission.ts
@@ -0,0 +1,126 @@
+import { useCallback, useEffect, useMemo, useState } from "react";
+
+import type { ObservationSessionReplayLaunch } from "./sessionArchive";
+import {
+  initialRecordedCameraAdmissions,
+  mergeRecordedCameraAdmission,
+  nextRecordedCameraPreparationIds,
+  recordedCameraDescriptorPreflight,
+  recordedSessionAdmissionPhase,
+  type RecordedAdmissionPhase,
+  type RecordedCameraAdmissionMap,
+  type RecordedCameraAdmissionState,
+} from "./recordedSessionAdmission";
+
+interface AdmissionSnapshot {
+  key: string | null;
+  spatialPhase: RecordedAdmissionPhase;
+  cameras: Record<string, RecordedCameraAdmissionState>;
+}
+
+export interface RecordedSessionAdmissionController {
+  key: string;
+  phase: RecordedAdmissionPhase;
+  cameraSourceIds: readonly string[];
+  cameras: RecordedCameraAdmissionMap;
+  activeCameraSourceIds: ReadonlySet<string>;
+  reportSpatial: (key: string, phase: RecordedAdmissionPhase) => void;
+  reportCamera: (
+    key: string,
+    sourceId: string,
+    state: RecordedCameraAdmissionState,
+  ) => void;
+}
+
+function replayAdmissionKey(replay: ObservationSessionReplayLaunch): string {
+  return [
+    replay.sessionId,
+    replay.sha256,
+    ...replay.mediaSources.map((source) => (
+      [
+        source.id,
+        source.manifestGenerationSha256,
+        source.byteLength,
+        source.timelineStartSeconds,
+        source.timelineEndSeconds,
+      ].join(":")
+    )),
+  ].join("|");
+}
+
+export function useRecordedSessionAdmission(
+  replay: ObservationSessionReplayLaunch | null,
+): RecordedSessionAdmissionController | null {
+  const key = replay ? replayAdmissionKey(replay) : null;
+  const cameraSourceIds = useMemo(
+    () => replay?.mediaSources.map(({ id }) => id) ?? [],
+    [replay],
+  );
+  const declaredByteLengths = useMemo(
+    () => Object.fromEntries(
+      (replay?.mediaSources ?? []).map(({ id, byteLength }) => [id, byteLength]),
+    ),
+    [replay],
+  );
+  const [snapshot, setSnapshot] = useState<AdmissionSnapshot>(() => ({
+    key,
+    spatialPhase: "loading",
+    cameras: initialRecordedCameraAdmissions(cameraSourceIds, declaredByteLengths),
+  }));
+
+  useEffect(() => {
+    setSnapshot({
+      key,
+      spatialPhase: "loading",
+      cameras: initialRecordedCameraAdmissions(cameraSourceIds, declaredByteLengths),
+    });
+  }, [cameraSourceIds, declaredByteLengths, key]);
+
+  const reportSpatial = useCallback((reportedKey: string, phase: RecordedAdmissionPhase) => {
+    setSnapshot((current) => current.key !== reportedKey
+      ? current
+      : { ...current, spatialPhase: phase });
+  }, []);
+
+  const reportCamera = useCallback((
+    reportedKey: string,
+    sourceId: string,
+    state: RecordedCameraAdmissionState,
+  ) => {
+    setSnapshot((current) => {
+      if (current.key !== reportedKey || !(sourceId in current.cameras)) return current;
+      const merged = mergeRecordedCameraAdmission(current.cameras[sourceId], state);
+      if (merged === current.cameras[sourceId]) return current;
+      return { ...current, cameras: { ...current.cameras, [sourceId]: merged } };
+    });
+  }, []);
+
+  if (!replay || !key) return null;
+  const current = snapshot.key === key
+    ? snapshot
+    : {
+        key,
+        spatialPhase: "loading" as const,
+        cameras: initialRecordedCameraAdmissions(cameraSourceIds, declaredByteLengths),
+      };
+  const descriptorPhase = recordedCameraDescriptorPreflight(replay.mediaSources);
+  const phase = descriptorPhase === "error"
+    ? "error"
+    : recordedSessionAdmissionPhase(
+        current.spatialPhase,
+        cameraSourceIds,
+        current.cameras,
+      );
+  const activeCameraSourceIds = new Set(phase === "error"
+    ? []
+    : nextRecordedCameraPreparationIds(cameraSourceIds, current.cameras));
+  return {
+    key,
+    phase,
+    cameraSourceIds,
+    cameras: current.cameras,
+    activeCameraSourceIds,
+    reportSpatial,
+    reportCamera,
+  };
+}
diff --git a/apps/control-station/src/core/observation/useWorkspaceLayoutProfile.ts b/apps/control-station/src/core/observation/useWorkspaceLayoutProfile.ts
new file mode 100644
index 0000000..d39ea8b
--- /dev/null
+++ b/apps/control-station/src/core/observation/useWorkspaceLayoutProfile.ts
@@ -0,0 +1,119 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+
+import {
+  fetchObservationWorkspaceLayoutProfile,
+  saveObservationWorkspaceLayoutProfile,
+  WorkspaceLayoutApiError,
+  type ObservationWorkspaceLayoutProfile,
+} from "./workspaceLayout";
+
+export type WorkspaceLayoutProfileState =
+  | "idle"
+  | "loading"
+  | "ready"
+  | "saving"
+  | "error"
+  | "conflict";
+
+export interface WorkspaceLayoutProfileController {
+  profile: ObservationWorkspaceLayoutProfile | null;
+  state: WorkspaceLayoutProfileState;
+  error: string | null;
+  refresh: () => Promise<ObservationWorkspaceLayoutProfile | null>;
+  save: (
+    profile: ObservationWorkspaceLayoutProfile,
+  ) => Promise<ObservationWorkspaceLayoutProfile | null>;
+}
+
+function errorMessage(error: unknown): string {
+  return error instanceof Error && error.message.trim()
+    ? error.message
+    : "Операция с профилем рабочей поверхности завершилась ошибкой.";
+}
+
+export function useWorkspaceLayoutProfile(): WorkspaceLayoutProfileController {
+  const [profile, setProfile] = useState<ObservationWorkspaceLayoutProfile | null>(null);
+  const profileRef = useRef<ObservationWorkspaceLayoutProfile | null>(null);
+  const [state, setState] = useState<WorkspaceLayoutProfileState>("idle");
+  const [error, setError] = useState<string | null>(null);
+  const mounted = useRef(true);
+  const requestSequence = useRef(0);
+  const saveInFlight = useRef(false);
+
+  const commitProfile = useCallback((next: ObservationWorkspaceLayoutProfile | null) => {
+    profileRef.current = next;
+    setProfile(next);
+  }, []);
+
+  const refresh = useCallback(async () => {
+    const sequence = ++requestSequence.current;
+    setState("loading");
+    setError(null);
+    try {
+      const loaded = await fetchObservationWorkspaceLayoutProfile();
+      if (!mounted.current || sequence !== requestSequence.current) return null;
+      commitProfile(loaded);
+      setState("ready");
+      return loaded;
+    } catch (loadError) {
+      if (!mounted.current || sequence !== requestSequence.current) return null;
+      setState("error");
+      setError(errorMessage(loadError));
+      return null;
+    }
+  }, [commitProfile]);
+
+  useEffect(() => {
+    mounted.current = true;
+    void refresh();
+    return () => {
+      mounted.current = false;
+      requestSequence.current += 1;
+    };
+  }, [refresh]);
+
+  useEffect(() => {
+    if (state !== "error") return;
+    // The desktop shell can become ready before its loopback API. Keep the
+    // last-layout restore self-healing instead of requiring a page reload once
+    // the local service finishes starting.
+    const timer = window.setTimeout(() => void refresh(), 5_000);
+    return () => window.clearTimeout(timer);
+  }, [refresh, state]);
+
+  useEffect(() => {
+    const refreshAfterNetworkRecovery = () => void refresh();
+    window.addEventListener("online", refreshAfterNetworkRecovery);
+    return () => window.removeEventListener("online", refreshAfterNetworkRecovery);
+  }, [refresh]);
+
+  const save = useCallback(async (draft: ObservationWorkspaceLayoutProfile) => {
+    if (saveInFlight.current) return null;
+    const current = profileRef.current;
+    if (current && draft.revision !== current.revision) {
+      setState("conflict");
+      setError("Профиль изменился после открытия. Обновите данные перед сохранением.");
+      return null;
+    }
+    saveInFlight.current = true;
+    setState("saving");
+    setError(null);
+    try {
+      const saved = await saveObservationWorkspaceLayoutProfile(draft);
+      if (!mounted.current) return null;
+      commitProfile(saved);
+      setState("ready");
+      return saved;
+    } catch (saveError) {
+      if (!mounted.current) return null;
+      const conflict = saveError instanceof WorkspaceLayoutApiError && saveError.conflict;
+      setState(conflict ? "conflict" : "error");
+      setError(errorMessage(saveError));
+      return null;
+    } finally {
+      saveInFlight.current = false;
+    }
+  }, [commitProfile]);
+
+  return { profile, state, error, refresh, save };
+}
diff --git a/apps/control-station/src/core/observation/workspaceLayout.ts b/apps/control-station/src/core/observation/workspaceLayout.ts
new file mode 100644
index 0000000..098c0be
--- /dev/null
+++ b/apps/control-station/src/core/observation/workspaceLayout.ts
@@ -0,0 +1,599 @@
+import type { SceneSettings } from "../../sceneSettings";
+
+export const OBSERVATION_WORKSPACE_ID = "observation.spatial" as const;
+export const OBSERVATION_WORKSPACE_LAYOUT_VERSION = 1 as const;
+export const OBSERVATION_WORKSPACE_LAYOUT_ENDPOINT =
+  "/api/v1/workspace-layouts/observation.spatial" as const;
+
+export type ObservationToolWindowId = "sources" | "display" | "layers";
+
+export interface ObservationToolWindows {
+  sourcesOpen: boolean;
+  displayOpen: boolean;
+  layersOpen: boolean;
+  order: readonly ObservationToolWindowId[];
+}
+
+export interface ObservationWindowRect {
+  x: number;
+  y: number;
+  width: number;
+  height: number;
+}
+
+export interface ObservationViewportSize {
+  width: number;
+  height: number;
+}
+
+export interface NormalizedObservationWindowRect {
+  x: number;
+  y: number;
+  width: number;
+  height: number;
+}
+
+export interface ObservationLayoutSnapshot {
+  visibleSourceIds: readonly string[];
+  activeFloatingSourceId: string | null;
+  windowRects: Readonly<Record<string, NormalizedObservationWindowRect>>;
+  viewportSize: ObservationViewportSize;
+}
+
+export interface ProjectedObservationLayout {
+  visibleSourceIds: readonly string[];
+  activeFloatingSourceId: string | null;
+  windowRects: Readonly<Record<string, ObservationWindowRect>>;
+}
+
+export interface ObservationWorkspaceLayoutProfile extends ObservationLayoutSnapshot {
+  version: typeof OBSERVATION_WORKSPACE_LAYOUT_VERSION;
+  revision: number;
+  workspaceId: typeof OBSERVATION_WORKSPACE_ID;
+  sceneSettings: SceneSettings;
+  toolWindows: ObservationToolWindows;
+}
+
+export type WorkspaceLayoutFetch = (
+  input: RequestInfo | URL,
+  init?: RequestInit,
+) => Promise<Response>;
+
+type WireProfile = {
+  version: number;
+  revision: number;
+  workspace_id: string;
+  scene_settings: {
+    projection: string;
+    point_size: number;
+    color_mode: string;
+    palette: string;
+    custom_color: string;
+    accumulation_seconds: number;
+    show_points: boolean;
+    show_trajectory: boolean;
+    show_grid: boolean;
+    show_labels: boolean;
+    show_camera_frustums: boolean;
+  };
+  tool_windows: {
+    sources_open: boolean;
+    display_open: boolean;
+    layers_open: boolean;
+    order: ObservationToolWindowId[];
+  };
+  visible_source_ids: string[];
+  active_floating_source_id: string | null;
+  window_rects: Record<string, NormalizedObservationWindowRect>;
+  viewport_size: ObservationViewportSize;
+};
+
+const PROFILE_KEYS = new Set([
+  "version",
+  "revision",
+  "workspace_id",
+  "scene_settings",
+  "tool_windows",
+  "visible_source_ids",
+  "active_floating_source_id",
+  "window_rects",
+  "viewport_size",
+]);
+const SCENE_KEYS = new Set([
+  "projection",
+  "point_size",
+  "color_mode",
+  "palette",
+  "custom_color",
+  "accumulation_seconds",
+  "show_points",
+  "show_trajectory",
+  "show_grid",
+  "show_labels",
+  "show_camera_frustums",
+]);
+const TOOL_WINDOW_KEYS = new Set(["sources_open", "display_open", "layers_open", "order"]);
+const VIEWPORT_KEYS = new Set(["width", "height"]);
+const RECT_KEYS = new Set(["x", "y", "width", "height"]);
+const PROJECTIONS = new Set<SceneSettings["projection"]>(["3d", "2d", "map"]);
+const COLOR_MODES = new Set<SceneSettings["colorMode"]>([
+  "intensity",
+  "height",
+  "distance",
+  "rgb",
+  "class",
+]);
+const PALETTES = new Set<SceneSettings["palette"]>([
+  "turbo",
+  "viridis",
+  "plasma",
+  "grayscale",
+  "custom",
+]);
+const TOOL_WINDOW_IDS = new Set<ObservationToolWindowId>(["sources", "display", "layers"]);
+const SAFE_STABLE_ID = /^[A-Za-z0-9][A-Za-z0-9._:-]{0,255}$/;
+const HEX_COLOR = /^#[0-9a-fA-F]{6}$/;
+const MAX_SOURCES = 256;
+const MAX_VIEWPORT_EDGE = 100_000;
+const NORMALIZED_EPSILON = 1e-9;
+
+export class WorkspaceLayoutContractError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "WorkspaceLayoutContractError";
+  }
+}
+
+export class WorkspaceLayoutApiError extends Error {
+  readonly status: number;
+
+  constructor(message: string, status = 0) {
+    super(message);
+    this.name = "WorkspaceLayoutApiError";
+    this.status = status;
+  }
+
+  get conflict(): boolean {
+    return this.status === 409 || this.status === 412;
+  }
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+function requireRecord(value: unknown, field: string): Record<string, unknown> {
+  if (!isRecord(value)) {
+    throw new WorkspaceLayoutContractError(`Поле ${field} должно быть объектом.`);
+  }
+  return value;
+}
+
+function assertExactKeys(
+  value: Record<string, unknown>,
+  expected: ReadonlySet<string>,
+  field: string,
+): void {
+  const actual = Object.keys(value);
+  const unknown = actual.filter((key) => !expected.has(key));
+  const missing = [...expected].filter((key) => !(key in value));
+  if (unknown.length || missing.length) {
+    const details = [
+      unknown.length ? `неизвестные: ${unknown.sort().join(", ")}` : "",
+      missing.length ? `отсутствуют: ${missing.sort().join(", ")}` : "",
+    ].filter(Boolean).join("; ");
+    throw new WorkspaceLayoutContractError(`${field}: неверная схема (${details}).`);
+  }
+}
+
+function requireBoolean(value: unknown, field: string): boolean {
+  if (typeof value !== "boolean") {
+    throw new WorkspaceLayoutContractError(`Поле ${field} должно быть boolean.`);
+  }
+  return value;
+}
+
+function requireFiniteInRange(
+  value: unknown,
+  field: string,
+  minimum: number,
+  maximum: number,
+  { integer = false, minimumExclusive = false }: { integer?: boolean; minimumExclusive?: boolean } = {},
+): number {
+  const belowMinimum = minimumExclusive
+    ? typeof value === "number" && value <= minimum
+    : typeof value === "number" && value < minimum;
+  if (
+    typeof value !== "number" ||
+    !Number.isFinite(value) ||
+    belowMinimum ||
+    value > maximum ||
+    (integer && !Number.isInteger(value))
+  ) {
+    throw new WorkspaceLayoutContractError(
+      `Поле ${field} должно быть конечным ${integer ? "целым " : ""}числом в допустимом диапазоне.`,
+    );
+  }
+  return value;
+}
+
+function requireStableId(value: unknown, field: string): string {
+  if (typeof value !== "string" || !SAFE_STABLE_ID.test(value)) {
+    throw new WorkspaceLayoutContractError(
+      `Поле ${field} должно содержать безопасный стабильный идентификатор источника.`,
+    );
+  }
+  return value;
+}
+
+function decodeViewport(value: unknown, field = "viewport_size"): ObservationViewportSize {
+  const record = requireRecord(value, field);
+  assertExactKeys(record, VIEWPORT_KEYS, field);
+  return {
+    width: requireFiniteInRange(record.width, `${field}.width`, 1, MAX_VIEWPORT_EDGE),
+    height: requireFiniteInRange(record.height, `${field}.height`, 1, MAX_VIEWPORT_EDGE),
+  };
+}
+
+export function validateObservationViewportSize(
+  value: ObservationViewportSize,
+): ObservationViewportSize {
+  return decodeViewport(value, "viewport");
+}
+
+function decodeNormalizedRect(
+  value: unknown,
+  field: string,
+): NormalizedObservationWindowRect {
+  const record = requireRecord(value, field);
+  assertExactKeys(record, RECT_KEYS, field);
+  const rect = {
+    x: requireFiniteInRange(record.x, `${field}.x`, 0, 1),
+    y: requireFiniteInRange(record.y, `${field}.y`, 0, 1),
+    width: requireFiniteInRange(record.width, `${field}.width`, 0, 1, { minimumExclusive: true }),
+    height: requireFiniteInRange(record.height, `${field}.height`, 0, 1, { minimumExclusive: true }),
+  };
+  if (
+    rect.x + rect.width > 1 + NORMALIZED_EPSILON ||
+    rect.y + rect.height > 1 + NORMALIZED_EPSILON
+  ) {
+    throw new WorkspaceLayoutContractError(`${field} выходит за нормализованные границы viewport.`);
+  }
+  return rect;
+}
+
+function decodeStableIds(value: unknown): string[] {
+  if (!Array.isArray(value) || value.length > MAX_SOURCES) {
+    throw new WorkspaceLayoutContractError(
+      `Поле visible_source_ids должно быть массивом не более ${MAX_SOURCES} элементов.`,
+    );
+  }
+  const result = value.map((entry, index) => requireStableId(entry, `visible_source_ids[${index}]`));
+  if (new Set(result).size !== result.length) {
+    throw new WorkspaceLayoutContractError("Поле visible_source_ids содержит повторяющиеся id.");
+  }
+  return result;
+}
+
+function decodeWindowRects(value: unknown): Record<string, NormalizedObservationWindowRect> {
+  const record = requireRecord(value, "window_rects");
+  if (Object.keys(record).length > MAX_SOURCES) {
+    throw new WorkspaceLayoutContractError(
+      `Поле window_rects содержит более ${MAX_SOURCES} элементов.`,
+    );
+  }
+  return Object.fromEntries(Object.entries(record).map(([sourceId, rect]) => [
+    requireStableId(sourceId, "window_rects key"),
+    decodeNormalizedRect(rect, `window_rects.${sourceId}`),
+  ]));
+}
+
+function requireEnum<T extends string>(
+  value: unknown,
+  allowed: ReadonlySet<T>,
+  field: string,
+): T {
+  if (typeof value !== "string" || !allowed.has(value as T)) {
+    throw new WorkspaceLayoutContractError(`Поле ${field} содержит неизвестное значение.`);
+  }
+  return value as T;
+}
+
+function decodeSceneSettings(value: unknown): SceneSettings {
+  const record = requireRecord(value, "scene_settings");
+  assertExactKeys(record, SCENE_KEYS, "scene_settings");
+  if (typeof record.custom_color !== "string" || !HEX_COLOR.test(record.custom_color)) {
+    throw new WorkspaceLayoutContractError("Поле scene_settings.custom_color должно быть цветом #RRGGBB.");
+  }
+  return {
+    projection: requireEnum(record.projection, PROJECTIONS, "scene_settings.projection"),
+    pointSize: requireFiniteInRange(record.point_size, "scene_settings.point_size", 0.1, 32),
+    colorMode: requireEnum(record.color_mode, COLOR_MODES, "scene_settings.color_mode"),
+    palette: requireEnum(record.palette, PALETTES, "scene_settings.palette"),
+    customColor: record.custom_color,
+    accumulationSeconds: requireFiniteInRange(
+      record.accumulation_seconds,
+      "scene_settings.accumulation_seconds",
+      0,
+      3_600,
+    ),
+    showPoints: requireBoolean(record.show_points, "scene_settings.show_points"),
+    showTrajectory: requireBoolean(record.show_trajectory, "scene_settings.show_trajectory"),
+    showGrid: requireBoolean(record.show_grid, "scene_settings.show_grid"),
+    showLabels: requireBoolean(record.show_labels, "scene_settings.show_labels"),
+    showCameraFrustums: requireBoolean(
+      record.show_camera_frustums,
+      "scene_settings.show_camera_frustums",
+    ),
+  };
+}
+
+function decodeToolWindows(value: unknown): ObservationToolWindows {
+  const record = requireRecord(value, "tool_windows");
+  assertExactKeys(record, TOOL_WINDOW_KEYS, "tool_windows");
+  if (!Array.isArray(record.order) || record.order.length !== TOOL_WINDOW_IDS.size) {
+    throw new WorkspaceLayoutContractError("Поле tool_windows.order должно содержать три окна.");
+  }
+  const order = record.order.map((entry, index) =>
+    requireEnum(entry, TOOL_WINDOW_IDS, `tool_windows.order[${index}]`));
+  if (new Set(order).size !== TOOL_WINDOW_IDS.size) {
+    throw new WorkspaceLayoutContractError("Поле tool_windows.order должно быть перестановкой окон.");
+  }
+  return {
+    sourcesOpen: requireBoolean(record.sources_open, "tool_windows.sources_open"),
+    displayOpen: requireBoolean(record.display_open, "tool_windows.display_open"),
+    layersOpen: requireBoolean(record.layers_open, "tool_windows.layers_open"),
+    order,
+  };
+}
+
+export function decodeObservationWorkspaceLayoutProfile(
+  value: unknown,
+): ObservationWorkspaceLayoutProfile {
+  const record = requireRecord(value, "workspace layout");
+  assertExactKeys(record, PROFILE_KEYS, "workspace layout");
+  if (record.version !== OBSERVATION_WORKSPACE_LAYOUT_VERSION) {
+    throw new WorkspaceLayoutContractError(
+      `Неподдерживаемая версия workspace layout: ${String(record.version)}.`,
+    );
+  }
+  if (record.workspace_id !== OBSERVATION_WORKSPACE_ID) {
+    throw new WorkspaceLayoutContractError("Профиль относится к другой рабочей поверхности.");
+  }
+  const visibleSourceIds = decodeStableIds(record.visible_source_ids);
+  const activeFloatingSourceId = record.active_floating_source_id === null
+    ? null
+    : requireStableId(record.active_floating_source_id, "active_floating_source_id");
+  if (activeFloatingSourceId && !visibleSourceIds.includes(activeFloatingSourceId)) {
+    throw new WorkspaceLayoutContractError(
+      "Активное плавающее окно должно относиться к видимому источнику.",
+    );
+  }
+  return {
+    version: OBSERVATION_WORKSPACE_LAYOUT_VERSION,
+    revision: requireFiniteInRange(record.revision, "revision", 0, Number.MAX_SAFE_INTEGER, {
+      integer: true,
+    }),
+    workspaceId: OBSERVATION_WORKSPACE_ID,
+    sceneSettings: decodeSceneSettings(record.scene_settings),
+    toolWindows: decodeToolWindows(record.tool_windows),
+    visibleSourceIds,
+    activeFloatingSourceId,
+    windowRects: decodeWindowRects(record.window_rects),
+    viewportSize: decodeViewport(record.viewport_size),
+  };
+}
+
+export function encodeObservationWorkspaceLayoutProfile(
+  profile: ObservationWorkspaceLayoutProfile,
+): WireProfile {
+  const wire: WireProfile = {
+    version: profile.version,
+    revision: profile.revision,
+    workspace_id: profile.workspaceId,
+    scene_settings: {
+      projection: profile.sceneSettings.projection,
+      point_size: profile.sceneSettings.pointSize,
+      color_mode: profile.sceneSettings.colorMode,
+      palette: profile.sceneSettings.palette,
+      custom_color: profile.sceneSettings.customColor,
+      accumulation_seconds: profile.sceneSettings.accumulationSeconds,
+      show_points: profile.sceneSettings.showPoints,
+      show_trajectory: profile.sceneSettings.showTrajectory,
+      show_grid: profile.sceneSettings.showGrid,
+      show_labels: profile.sceneSettings.showLabels,
+      show_camera_frustums: profile.sceneSettings.showCameraFrustums,
+    },
+    tool_windows: {
+      sources_open: profile.toolWindows.sourcesOpen,
+      display_open: profile.toolWindows.displayOpen,
+      layers_open: profile.toolWindows.layersOpen,
+      order: [...profile.toolWindows.order],
+    },
+    visible_source_ids: [...profile.visibleSourceIds],
+    active_floating_source_id: profile.activeFloatingSourceId,
+    window_rects: Object.fromEntries(
+      Object.entries(profile.windowRects).map(([sourceId, rect]) => [sourceId, { ...rect }]),
+    ),
+    viewport_size: { ...profile.viewportSize },
+  };
+  // The decoder is the single runtime schema authority for inbound and outbound documents.
+  decodeObservationWorkspaceLayoutProfile(wire);
+  return wire;
+}
+
+function clamp(value: number, minimum: number, maximum: number): number {
+  return Math.min(maximum, Math.max(minimum, value));
+}
+
+export function normalizeObservationWindowRect(
+  rect: ObservationWindowRect,
+  viewport: ObservationViewportSize,
+): NormalizedObservationWindowRect {
+  const safeViewport = decodeViewport(viewport, "viewport");
+  for (const [field, value] of Object.entries(rect)) {
+    if (typeof value !== "number" || !Number.isFinite(value)) {
+      throw new WorkspaceLayoutContractError(`Поле rect.${field} должно быть конечным числом.`);
+    }
+  }
+  const x = clamp(rect.x, 0, Math.max(0, safeViewport.width - 1));
+  const y = clamp(rect.y, 0, Math.max(0, safeViewport.height - 1));
+  const width = clamp(rect.width, 1, Math.max(1, safeViewport.width - x));
+  const height = clamp(rect.height, 1, Math.max(1, safeViewport.height - y));
+  return {
+    x: x / safeViewport.width,
+    y: y / safeViewport.height,
+    width: width / safeViewport.width,
+    height: height / safeViewport.height,
+  };
+}
+
+export function denormalizeObservationWindowRect(
+  rect: NormalizedObservationWindowRect,
+  viewport: ObservationViewportSize,
+): ObservationWindowRect {
+  const normalized = decodeNormalizedRect(rect, "rect");
+  const safeViewport = decodeViewport(viewport, "viewport");
+  return {
+    x: normalized.x * safeViewport.width,
+    y: normalized.y * safeViewport.height,
+    width: normalized.width * safeViewport.width,
+    height: normalized.height * safeViewport.height,
+  };
+}
+
+export function validateObservationLayoutSnapshot(
+  snapshot: ObservationLayoutSnapshot,
+): ObservationLayoutSnapshot {
+  const wire = {
+    version: OBSERVATION_WORKSPACE_LAYOUT_VERSION,
+    revision: 0,
+    workspace_id: OBSERVATION_WORKSPACE_ID,
+    scene_settings: {
+      projection: "3d",
+      point_size: 1,
+      color_mode: "intensity",
+      palette: "turbo",
+      custom_color: "#ffffff",
+      accumulation_seconds: 0,
+      show_points: true,
+      show_trajectory: true,
+      show_grid: true,
+      show_labels: false,
+      show_camera_frustums: true,
+    },
+    tool_windows: {
+      sources_open: false,
+      display_open: false,
+      layers_open: false,
+      order: ["sources", "display", "layers"],
+    },
+    visible_source_ids: [...snapshot.visibleSourceIds],
+    active_floating_source_id: snapshot.activeFloatingSourceId,
+    window_rects: snapshot.windowRects,
+    viewport_size: snapshot.viewportSize,
+  };
+  const decoded = decodeObservationWorkspaceLayoutProfile(wire);
+  return {
+    visibleSourceIds: decoded.visibleSourceIds,
+    activeFloatingSourceId: decoded.activeFloatingSourceId,
+    windowRects: decoded.windowRects,
+    viewportSize: decoded.viewportSize,
+  };
+}
+
+export function projectObservationLayoutSnapshot(
+  snapshot: ObservationLayoutSnapshot,
+  knownSourceIds: ReadonlySet<string>,
+  viewport: ObservationViewportSize,
+): ProjectedObservationLayout {
+  const validated = validateObservationLayoutSnapshot(snapshot);
+  const targetViewport = decodeViewport(viewport, "viewport");
+  const visibleSourceIds = validated.visibleSourceIds.filter((sourceId) => knownSourceIds.has(sourceId));
+  const visibleSet = new Set(visibleSourceIds);
+  return {
+    visibleSourceIds,
+    activeFloatingSourceId: validated.activeFloatingSourceId && visibleSet.has(validated.activeFloatingSourceId)
+      ? validated.activeFloatingSourceId
+      : null,
+    windowRects: Object.fromEntries(
+      Object.entries(validated.windowRects)
+        .filter(([sourceId]) => knownSourceIds.has(sourceId))
+        .map(([sourceId, rect]) => [
+          sourceId,
+          denormalizeObservationWindowRect(rect, targetViewport),
+        ]),
+    ),
+  };
+}
+
+async function responseMessage(response: Response, fallback: string): Promise<string> {
+  try {
+    const body: unknown = await response.json();
+    if (isRecord(body) && typeof body.detail === "string" && body.detail.trim()) {
+      return body.detail.trim();
+    }
+  } catch {
+    // A non-JSON error body is represented by the stable fallback.
+  }
+  return fallback;
+}
+
+export async function fetchObservationWorkspaceLayoutProfile({
+  fetcher = fetch,
+}: { fetcher?: WorkspaceLayoutFetch } = {}): Promise<ObservationWorkspaceLayoutProfile | null> {
+  const response = await fetcher(OBSERVATION_WORKSPACE_LAYOUT_ENDPOINT, {
+    method: "GET",
+    headers: { Accept: "application/json" },
+    cache: "no-store",
+  });
+  if (response.status === 404) return null;
+  if (!response.ok) {
+    throw new WorkspaceLayoutApiError(
+      await responseMessage(response, "Не удалось загрузить профиль рабочей поверхности."),
+      response.status,
+    );
+  }
+  let body: unknown;
+  try {
+    body = await response.json();
+  } catch {
+    throw new WorkspaceLayoutContractError("Сервер вернул профиль не в формате JSON.");
+  }
+  return decodeObservationWorkspaceLayoutProfile(body);
+}
+
+export async function saveObservationWorkspaceLayoutProfile(
+  profile: ObservationWorkspaceLayoutProfile,
+  { fetcher = fetch }: { fetcher?: WorkspaceLayoutFetch } = {},
+): Promise<ObservationWorkspaceLayoutProfile> {
+  const wire = encodeObservationWorkspaceLayoutProfile(profile);
+  const response = await fetcher(OBSERVATION_WORKSPACE_LAYOUT_ENDPOINT, {
+    method: "PUT",
+    headers: {
+      Accept: "application/json",
+      "Content-Type": "application/json",
+      "If-Match": `"${profile.revision}"`,
+    },
+    body: JSON.stringify(wire),
+  });
+  if (!response.ok) {
+    throw new WorkspaceLayoutApiError(
+      await responseMessage(response, response.status === 409 || response.status === 412
+        ? "Профиль уже изменён в другом окне. Обновите данные и повторите сохранение."
+        : "Не удалось сохранить профиль рабочей поверхности."),
+      response.status,
+    );
+  }
+  let body: unknown;
+  try {
+    body = await response.json();
+  } catch {
+    throw new WorkspaceLayoutContractError("Сервер не вернул сохранённый профиль в формате JSON.");
+  }
+  const saved = decodeObservationWorkspaceLayoutProfile(body);
+  if (saved.revision <= profile.revision) {
+    throw new WorkspaceLayoutContractError("Сервер не увеличил revision сохранённого профиля.");
+  }
+  return saved;
+}
diff --git a/apps/control-station/src/core/runtime/contracts.ts b/apps/control-station/src/core/runtime/contracts.ts
index 17175f1..bb481b0 100644
--- a/apps/control-station/src/core/runtime/contracts.ts
+++ b/apps/control-station/src/core/runtime/contracts.ts
@@ -123,6 +123,16 @@ export type ObservationSourceDelivery =
       kind: "video-url" | "image-url";
       url: string;
       mediaType?: string | null;
+    }
+  | {
+      id: string;
+      kind: "recorded-fmp4-manifest";
+      url: string;
+      mediaType: "video/mp4";
+      manifestGenerationSha256: string;
+      byteLength: number;
+      timelineStartSeconds: number;
+      timelineEndSeconds: number;
     };
 
 export interface ObservationSourceActivation {
diff --git a/apps/control-station/src/core/runtime/latestAsyncCommitter.ts b/apps/control-station/src/core/runtime/latestAsyncCommitter.ts
new file mode 100644
index 0000000..b991955
--- /dev/null
+++ b/apps/control-station/src/core/runtime/latestAsyncCommitter.ts
@@ -0,0 +1,89 @@
+export interface LatestAsyncCommitter<T> {
+  enqueue: (value: T) => void;
+  hasPending: () => boolean;
+  isBusy: () => boolean;
+  waitForIdle: () => Promise<void>;
+  dispose: () => void;
+}
+
+export interface LatestAsyncCommitResult<T> {
+  value: T;
+  applied: boolean;
+  superseded: boolean;
+}
+
+/**
+ * Serializes an expensive settings commit while retaining only the newest
+ * value submitted during the active request. This keeps slider and color
+ * interactions from creating an unbounded backend queue.
+ */
+export function createLatestAsyncCommitter<T>({
+  commit,
+  onSettled,
+}: {
+  commit: (value: T) => Promise<boolean>;
+  onSettled?: (result: LatestAsyncCommitResult<T>) => void;
+}): LatestAsyncCommitter<T> {
+  let pending: T | undefined;
+  let running = false;
+  let disposed = false;
+  const idleWaiters = new Set<() => void>();
+
+  const settleIdleWaiters = () => {
+    if (running || pending !== undefined) return;
+    for (const resolve of idleWaiters) resolve();
+    idleWaiters.clear();
+  };
+
+  const drain = async () => {
+    if (running || disposed) return;
+    running = true;
+
+    try {
+      while (!disposed && pending !== undefined) {
+        const value = pending;
+        pending = undefined;
+
+        let applied = false;
+        try {
+          applied = await commit(value);
+        } catch {
+          applied = false;
+        }
+
+        if (disposed) return;
+        onSettled?.({
+          value,
+          applied,
+          superseded: pending !== undefined,
+        });
+      }
+    } finally {
+      running = false;
+      if (!disposed && pending !== undefined) {
+        void drain();
+      } else {
+        settleIdleWaiters();
+      }
+    }
+  };
+
+  return {
+    enqueue(value) {
+      if (disposed) return;
+      pending = value;
+      void drain();
+    },
+    hasPending: () => pending !== undefined,
+    isBusy: () => running || pending !== undefined,
+    waitForIdle() {
+      if (!running && pending === undefined) return Promise.resolve();
+      return new Promise<void>((resolve) => idleWaiters.add(resolve));
+    },
+    dispose() {
+      disposed = true;
+      pending = undefined;
+      settleIdleWaiters();
+    },
+  };
+}
diff --git a/apps/control-station/src/styles/observation-sessions.css b/apps/control-station/src/styles/observation-sessions.css
new file mode 100644
index 0000000..c1c4b08
--- /dev/null
+++ b/apps/control-station/src/styles/observation-sessions.css
@@ -0,0 +1,233 @@
+.observation-header-tools {
+  display: flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: 0.65rem;
+}
+
+.workspace-layout-feedback {
+  display: inline-flex;
+  max-width: 15rem;
+  align-items: center;
+  gap: 0.45rem;
+  color: var(--nodedc-text-muted);
+  font-size: var(--nodedc-font-size-xs);
+  line-height: 1.2;
+}
+
+.workspace-layout-feedback[data-error="true"] {
+  color: rgb(var(--nodedc-danger-rgb));
+}
+
+.observation-session-select__trigger {
+  display: inline-flex;
+  min-width: 15rem;
+  height: 2.75rem;
+  align-items: center;
+  justify-content: flex-start;
+  gap: 0.55rem;
+  border: 0;
+  border-radius: 999px;
+  background: rgb(255 255 255 / 0.055);
+  color: var(--nodedc-text-secondary);
+  padding: 0 0.85rem;
+  font: inherit;
+  font-size: var(--nodedc-font-size-sm);
+  font-weight: var(--nodedc-font-weight-strong);
+  cursor: pointer;
+}
+
+.observation-session-select__trigger:hover,
+.observation-session-select__trigger[data-active="true"] {
+  background: rgb(255 255 255 / 0.095);
+  color: var(--nodedc-text-primary);
+}
+
+.observation-session-select__trigger > span {
+  min-width: 0;
+  flex: 1 1 auto;
+  overflow: hidden;
+  text-align: left;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.observation-session-select__trigger > small {
+  display: grid;
+  min-width: 1.35rem;
+  height: 1.35rem;
+  place-items: center;
+  border-radius: 999px;
+  background: rgb(255 255 255 / 0.08);
+  color: var(--nodedc-text-muted);
+  font-size: var(--nodedc-font-size-xs);
+}
+
+.observation-session-menu {
+  overflow: hidden;
+  font-family: var(--nodedc-font-family);
+}
+
+.observation-session-menu__content,
+.observation-session-menu__list {
+  display: grid;
+}
+
+.observation-session-menu__head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1rem;
+  padding: 0.85rem 0.9rem 0.6rem;
+}
+
+.observation-session-menu__head span,
+.observation-session-menu__head strong {
+  display: block;
+}
+
+.observation-session-menu__head strong {
+  margin-top: 0.3rem;
+  color: var(--nodedc-text-primary);
+  font-size: var(--nodedc-font-size-md);
+}
+
+.observation-session-menu__head button {
+  display: grid;
+  width: 2rem;
+  height: 2rem;
+  place-items: center;
+  border: 0;
+  border-radius: 50%;
+  background: rgb(255 255 255 / 0.055);
+  color: var(--nodedc-text-secondary);
+  cursor: pointer;
+}
+
+.observation-session-menu__head button:hover {
+  background: rgb(255 255 255 / 0.1);
+  color: var(--nodedc-text-primary);
+}
+
+.observation-session-menu__list {
+  max-height: min(26rem, 60vh);
+  gap: 0.2rem;
+  overflow: auto;
+  padding: 0.35rem;
+}
+
+.observation-session-option {
+  grid-template-columns: auto minmax(0, 1fr) auto;
+}
+
+.observation-session-option i {
+  display: block;
+  width: 0.45rem;
+  height: 0.45rem;
+  border-radius: 50%;
+  background: var(--nodedc-text-muted);
+}
+
+.observation-session-option i[data-session-visual-state="ready"],
+.observation-session-option i[data-session-visual-state="processing"] {
+  background: rgb(var(--nodedc-success-rgb));
+}
+
+.observation-session-option i[data-session-visual-state="processing"] {
+  animation: observation-session-processing 1.1s ease-in-out infinite;
+}
+
+.observation-session-option i[data-session-visual-state="error"] {
+  background: var(--nodedc-text-muted);
+  opacity: 0.48;
+}
+
+@keyframes observation-session-processing {
+  0%, 100% { opacity: 0.3; }
+  50% { opacity: 1; }
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .observation-session-option i[data-session-visual-state="processing"] {
+    animation: none;
+    opacity: 0.72;
+  }
+}
+
+.observation-session-option__state {
+  max-width: 9.5rem;
+  overflow: hidden;
+  color: var(--nodedc-text-muted);
+  font-size: var(--nodedc-font-size-xs);
+  font-weight: var(--nodedc-font-weight-medium);
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.observation-session-menu__empty {
+  display: grid;
+  min-height: 9rem;
+  place-items: center;
+  align-content: center;
+  gap: 0.5rem;
+  padding: 1rem;
+  color: var(--nodedc-text-muted);
+  text-align: center;
+}
+
+.observation-session-menu__empty strong {
+  color: var(--nodedc-text-secondary);
+  font-size: var(--nodedc-font-size-sm);
+}
+
+.observation-session-menu__empty span {
+  max-width: 24rem;
+  font-size: var(--nodedc-font-size-xs);
+  line-height: 1.45;
+}
+
+.observation-session-menu__error {
+  display: flex;
+  align-items: flex-start;
+  gap: 0.45rem;
+  padding: 0.65rem 0.9rem 0.8rem;
+  color: rgb(var(--nodedc-danger-rgb));
+  font-size: var(--nodedc-font-size-xs);
+  line-height: 1.4;
+}
+
+.observation-session-menu__error > span {
+  min-width: 0;
+  flex: 1 1 auto;
+}
+
+.observation-session-menu__error button {
+  flex: 0 0 auto;
+  border: 0;
+  border-radius: 999px;
+  background: rgb(255 255 255 / 0.08);
+  color: var(--nodedc-text-primary);
+  padding: 0.4rem 0.65rem;
+  font: inherit;
+  font-weight: var(--nodedc-font-weight-strong);
+  cursor: pointer;
+}
+
+@media (max-width: 860px) {
+  .workspace-layout-feedback {
+    display: none;
+  }
+
+  .observation-session-select__trigger {
+    min-width: 2.75rem;
+    width: 2.75rem;
+    padding: 0;
+    justify-content: center;
+  }
+
+  .observation-session-select__trigger > span,
+  .observation-session-select__trigger > small,
+  .observation-session-select__trigger > svg:last-child {
+    display: none;
+  }
+}
diff --git a/apps/control-station/src/styles/observation.css b/apps/control-station/src/styles/observation.css
index 04d8ee0..a783115 100644
--- a/apps/control-station/src/styles/observation.css
+++ b/apps/control-station/src/styles/observation.css
@@ -191,6 +191,32 @@ i[data-availability="error"] {
   background: #050608;
 }
 
+.recorded-media-player {
+  position: relative;
+  width: 100%;
+  height: 100%;
+  overflow: hidden;
+  background: #070809;
+}
+
+.recorded-media-player:not([data-state="ready"]) .observation-media__asset {
+  visibility: hidden;
+}
+
+.recorded-media-player__notice {
+  position: absolute;
+  inset: 0;
+  display: grid;
+  place-items: center;
+  padding: 18px;
+  color: rgba(247, 248, 244, 0.72);
+  background: #070809;
+  font: inherit;
+  font-size: 11px;
+  text-align: center;
+  pointer-events: none;
+}
+
 .mse-fmp4-player {
   position: relative;
   width: 100%;
@@ -316,11 +342,8 @@ i[data-availability="error"] {
 }
 
 .observation-timeline {
-  display: grid;
+  display: block;
   min-width: 0;
-  grid-template-columns: auto auto minmax(0, 1fr) auto auto;
-  align-items: center;
-  gap: 0.6rem;
   border: 0;
   border-radius: 0.9rem;
   background: rgb(9 10 13 / 0.78);
@@ -328,22 +351,73 @@ i[data-availability="error"] {
   backdrop-filter: blur(16px);
 }
 
-.observation-timeline__track {
-  height: 0.3rem;
-  overflow: hidden;
-  border-radius: 999px;
-  background: rgb(255 255 255 / 0.08);
+.observation-timeline[data-accumulation="true"] {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  align-items: center;
+  gap: 0.8rem;
 }
 
-.observation-timeline__track span {
-  display: block;
-  height: 100%;
-  border-radius: inherit;
+.observation-timeline__playback {
+  display: grid;
+  min-width: 0;
+  grid-template-columns: auto auto minmax(0, 1fr) auto auto;
+  align-items: center;
+  gap: 0.6rem;
+}
+
+.observation-timeline__accumulation {
+  display: grid;
+  min-width: 0;
+  grid-template-columns: auto minmax(0, 1fr) auto;
+  align-items: center;
+  gap: 0.7rem;
+  padding: 0 0.45rem;
+}
+
+.observation-timeline__accumulation span,
+.observation-timeline__accumulation code {
+  color: var(--nodedc-text-muted);
+  font-size: 0.55rem;
+  white-space: nowrap;
+}
+
+.observation-timeline__accumulation code {
+  min-width: 2.65rem;
+  color: var(--nodedc-text-primary);
+  text-align: right;
+}
+
+.observation-timeline__track {
+  width: 100%;
+  height: 0.3rem;
+  appearance: none;
+  border: 0;
+  border-radius: 999px;
+  background: rgb(255 255 255 / 0.08);
+  cursor: pointer;
+}
+
+.observation-timeline__track::-webkit-slider-thumb {
+  width: 0.72rem;
+  height: 0.72rem;
+  appearance: none;
+  border: 0;
+  border-radius: 50%;
   background: var(--nodedc-text-primary);
 }
 
-.observation-timeline__track[data-disabled="true"] {
+.observation-timeline__track::-moz-range-thumb {
+  width: 0.72rem;
+  height: 0.72rem;
+  border: 0;
+  border-radius: 50%;
+  background: var(--nodedc-text-primary);
+}
+
+.observation-timeline__track:disabled {
   opacity: 0.46;
+  cursor: default;
 }
 
 .observation-timeline__meta {
@@ -364,11 +438,17 @@ i[data-availability="error"] {
   align-items: center;
   gap: 0.38rem;
   color: var(--nodedc-text-muted);
+  border: 0;
+  background: transparent;
   padding: 0.3rem 0.45rem;
   font-size: 0.52rem;
   font-weight: 820;
 }
 
+.observation-timeline__follow:not(:disabled) {
+  cursor: pointer;
+}
+
 .observation-timeline__follow::before {
   width: 0.4rem;
   height: 0.4rem;
@@ -514,11 +594,15 @@ i[data-availability="error"] {
     left: 0.6rem;
   }
 
-  .observation-timeline {
+  .observation-timeline[data-accumulation="true"] {
+    grid-template-columns: minmax(0, 1fr);
+  }
+
+  .observation-timeline__playback {
     grid-template-columns: auto minmax(0, 1fr) auto;
   }
 
-  .observation-timeline > .nodedc-button:first-child,
+  .observation-timeline__playback > .nodedc-button:first-child,
   .observation-timeline__meta {
     display: none;
   }
diff --git a/apps/control-station/src/styles/responsive.css b/apps/control-station/src/styles/responsive.css
index ef91874..77e2bbd 100644
--- a/apps/control-station/src/styles/responsive.css
+++ b/apps/control-station/src/styles/responsive.css
@@ -104,7 +104,6 @@
 }
 
 @media (max-width: 760px) {
-  .station-label,
   .control-station .nodedc-header__profile-button {
     display: none;
   }
diff --git a/apps/control-station/src/styles/shell.css b/apps/control-station/src/styles/shell.css
index 37032be..0aa2bdb 100644
--- a/apps/control-station/src/styles/shell.css
+++ b/apps/control-station/src/styles/shell.css
@@ -1,13 +1,3 @@
-.station-label {
-  overflow: hidden;
-  color: var(--nodedc-text-muted);
-  font-size: 0.61rem;
-  font-weight: 820;
-  letter-spacing: 0.13em;
-  text-overflow: ellipsis;
-  white-space: nowrap;
-}
-
 .api-dot {
   width: 0.48rem;
   height: 0.48rem;
diff --git a/apps/control-station/src/styles/spatial.css b/apps/control-station/src/styles/spatial.css
index 5919e91..1ce67a9 100644
--- a/apps/control-station/src/styles/spatial.css
+++ b/apps/control-station/src/styles/spatial.css
@@ -45,17 +45,34 @@
   min-height: 0;
 }
 
+.rerun-viewport__canvas[data-presented="false"] {
+  visibility: hidden;
+}
+
+.recorded-session-preloaders {
+  position: fixed;
+  left: -10000px;
+  top: -10000px;
+  width: 1px;
+  height: 1px;
+  overflow: hidden;
+  opacity: 0;
+  pointer-events: none;
+}
+
 .rerun-viewport {
-  --rerun-tab-bar-height: 24px;
+  --rerun-native-chrome-height: 72px;
   overflow: hidden;
 }
 
-/* Rerun WebViewer 0.34.1 draws its selected recording tab inside WASM.
-   The native panels are already disabled; crop only that fixed tab row. */
+/* Rerun WebViewer 0.34.1 keeps three fixed 24px canvas rows even after its
+   panels are overridden: the native top row, recording tab and view tab.
+   They are drawn inside WASM and cannot be styled independently, so crop the
+   fixed native chrome while keeping the actual 3D viewport full-height. */
 .rerun-viewport__canvas {
-  top: calc(-1 * var(--rerun-tab-bar-height));
+  top: calc(-1 * var(--rerun-native-chrome-height));
   bottom: auto;
-  height: calc(100% + var(--rerun-tab-bar-height));
+  height: calc(100% + var(--rerun-native-chrome-height));
 }
 
 .rerun-viewport__canvas canvas {
@@ -65,8 +82,9 @@
 }
 
 .rerun-viewport:is([data-status="loading"], [data-status="error"])
-  .rerun-viewport__canvas > div {
+  .rerun-viewport__canvas {
   visibility: hidden;
+  pointer-events: none;
 }
 
 .rerun-viewport__notice {
diff --git a/apps/control-station/src/workspaces/Workspaces.tsx b/apps/control-station/src/workspaces/Workspaces.tsx
index 30201b8..8122bf6 100644
--- a/apps/control-station/src/workspaces/Workspaces.tsx
+++ b/apps/control-station/src/workspaces/Workspaces.tsx
@@ -14,6 +14,12 @@ import {
 } from "../components/ObservationSources";
 import { ObservationTimeline } from "../components/ObservationTimeline";
 import { FloatingObservationWindow } from "../components/FloatingObservationWindow";
+import type { ObservationSessionReplayLaunch } from "../core/observation/sessionArchive";
+import type { RecordedSessionAdmissionController } from "../core/observation/useRecordedSessionAdmission";
+import type {
+  RecordedAdmissionPhase,
+  RecordedCameraAdmissionState,
+} from "../core/observation/recordedSessionAdmission";
 import type { ObservationLayoutController } from "../core/observation/useObservationLayout";
 import type {
   BackendStatus,
@@ -22,6 +28,10 @@ import type {
 } from "../core/runtime/contracts";
 import {
   RerunViewport,
+  isRecordedPlaybackPresentationReady,
+  rerunPresentationStatus,
+  type RerunPlaybackController,
+  type RerunPlaybackState,
   type RerunSelection,
   type RerunViewportStatus,
 } from "../components/RerunViewport";
@@ -95,7 +105,12 @@ export interface WorkspaceRendererProps {
   state: MissionRuntimeState | null;
   backendStatus: BackendStatus;
   sourceUrl: string;
+  recordedReplay: ObservationSessionReplayLaunch | null;
+  recordedSessionAdmission: RecordedSessionAdmissionController | null;
   sceneSettings: SceneSettings;
+  accumulationSeconds: number;
+  onAccumulationChange: (value: number) => void;
+  onAccumulationCommit: () => void;
   observationLayout: ObservationLayoutController;
   navigation: WorkspaceNavigation;
 }
@@ -248,13 +263,27 @@ function EmptySpatialStage({ settings }: { settings: SceneSettings }) {
 function SpatialWorkspace({
   state,
   sourceUrl,
+  recordedReplay,
+  recordedSessionAdmission,
   sceneSettings,
+  accumulationSeconds,
+  onAccumulationChange,
+  onAccumulationCommit,
   observationLayout,
   navigation,
 }: WorkspaceRendererProps) {
   const [viewerStatus, setViewerStatus] = useState<RerunViewportStatus>(sourceUrl ? "loading" : "idle");
   const [viewerMessage, setViewerMessage] = useState("");
   const [selection, setSelection] = useState<RerunSelection | null>(null);
+  const [playbackState, setPlaybackState] = useState<RerunPlaybackState | null>(null);
+  const [playbackController, setPlaybackController] = useState<RerunPlaybackController | null>(null);
+  const recordedSource = state?.sourceMode === "replay" || /\.rrd(?:$|[?#])/i.test(sourceUrl);
+  const recordedSessionGate: RecordedAdmissionPhase = recordedSource
+    ? recordedSessionAdmission?.phase ?? "loading"
+    : "ready";
+  const recordedPlaybackReady = !recordedSource ||
+    (recordedSessionGate === "ready" &&
+      isRecordedPlaybackPresentationReady(viewerStatus, playbackState));
   const streamActive = state?.sourceMode === "live" || state?.sourceMode === "replay";
   const metrics = streamActive ? state?.metrics : undefined;
   const latency = pipelineLatency(metrics);
@@ -277,28 +306,83 @@ function SpatialWorkspace({
   const floatingSourceMaximized = Boolean(observationLayout.maximizedFloatingSourceId);
   const timeline = state?.observationTimeline;
   const viewportRef = useRef<HTMLDivElement>(null);
+  const presentedViewerStatus = rerunPresentationStatus(
+    viewerStatus,
+    recordedSessionGate,
+    recordedSource,
+  );
 
   const onStatusChange = useCallback((status: RerunViewportStatus, message?: string) => {
     setViewerStatus(status);
     setViewerMessage(message ?? "");
-  }, []);
+    if (recordedSessionAdmission) {
+      recordedSessionAdmission.reportSpatial(
+        recordedSessionAdmission.key,
+        status === "ready" ? "ready" : status === "error" ? "error" : "loading",
+      );
+    }
+  }, [recordedSessionAdmission?.key, recordedSessionAdmission?.reportSpatial]);
+  const onRecordedAdmissionChange = useCallback((
+    sourceId: string,
+    next: RecordedCameraAdmissionState,
+  ) => {
+    if (!recordedSessionAdmission) return;
+    if (next.admissionKey !== recordedSessionAdmission.key) return;
+    recordedSessionAdmission.reportCamera(recordedSessionAdmission.key, sourceId, next);
+  }, [recordedSessionAdmission?.key, recordedSessionAdmission?.reportCamera]);
+  const shouldPrepareRecordedSource = useCallback((sourceId: string) => {
+    if (!recordedSessionAdmission) return false;
+    return recordedSessionAdmission.activeCameraSourceIds.has(sourceId) ||
+      recordedSessionAdmission.cameras[sourceId]?.phase === "ready";
+  }, [recordedSessionAdmission]);
   const onSelectionChange = useCallback((next: RerunSelection | null) => setSelection(next), []);
+  const onPlaybackChange = useCallback(
+    (next: RerunPlaybackState | null) => setPlaybackState(next),
+    [],
+  );
+  const onPlaybackControllerChange = useCallback(
+    (next: RerunPlaybackController | null) => setPlaybackController(next),
+    [],
+  );
 
   useEffect(() => {
     if (pointCloudVisible && sourceUrl.trim()) return;
     setViewerStatus("idle");
     setViewerMessage("");
     setSelection(null);
+    setPlaybackState(null);
+    setPlaybackController(null);
   }, [pointCloudVisible, sourceUrl]);
 
+  useEffect(() => {
+    const viewport = viewportRef.current;
+    if (!viewport) return;
+    const publishViewportSize = () => {
+      const bounds = viewport.getBoundingClientRect();
+      if (bounds.width < 1 || bounds.height < 1) return;
+      observationLayout.setViewportSize({
+        width: bounds.width,
+        height: bounds.height,
+      });
+    };
+    publishViewportSize();
+    const observer = new ResizeObserver(publishViewportSize);
+    observer.observe(viewport);
+    return () => observer.disconnect();
+  }, [observationLayout.setViewportSize]);
+
   const viewerStatusLabel = {
     idle: "Источник не назначен",
     loading: "Подключение",
     ready: "Визуализатор готов",
     error: "Ошибка источника",
-  }[viewerStatus];
+  }[presentedViewerStatus];
 
-  const viewerStatusTone = viewerStatus === "ready" ? "success" : viewerStatus === "error" ? "danger" : "neutral";
+  const viewerStatusTone = presentedViewerStatus === "ready"
+    ? "success"
+    : presentedViewerStatus === "error"
+      ? "danger"
+      : "neutral";
 
   return (
     <div
@@ -331,9 +415,21 @@ function SpatialWorkspace({
           {sourceUrl.trim() && pointCloudVisible ? (
             <RerunViewport
               sourceUrl={sourceUrl}
-              followLive={state?.sourceMode === "live"}
+              recordedArtifact={recordedSource ? recordedReplay : null}
+              followLive={!recordedSource && state?.sourceMode === "live"}
+              autoplayWhenReady={recordedSource}
+              presentationGate={recordedSessionGate}
+              expectedTimelineStartSeconds={recordedSource
+                ? state?.observationTimeline?.range?.startSeconds
+                : undefined}
+              expectedTimelineEndSeconds={recordedSource
+                ? state?.observationTimeline?.range?.endSeconds
+                : undefined}
+              sceneSettings={sceneSettings}
               onStatusChange={onStatusChange}
               onSelectionChange={onSelectionChange}
+              onPlaybackChange={onPlaybackChange}
+              onPlaybackControllerChange={onPlaybackControllerChange}
             />
           ) : (
             <EmptySpatialStage settings={sceneSettings} />
@@ -415,13 +511,26 @@ function SpatialWorkspace({
             </div>
           ) : null}
 
-          {!pointCloudFocused && !floatingSourceMaximized ? (
+          {!pointCloudFocused && !floatingSourceMaximized && recordedPlaybackReady ? (
             <ObservationTimeline
-              active={viewerStatus === "ready"}
+              active={presentedViewerStatus === "ready"}
               sourceCount={Math.max(1, 1 + visibleMediaSources.length)}
-              mode={timeline?.mode}
-              seekable={timeline?.seekable}
+              mode={recordedSource && playbackState?.rangeNs
+                ? "recorded"
+                : timeline?.mode}
+              seekable={recordedSource && playbackState?.rangeNs
+                ? true
+                : timeline?.seekable}
               synchronization={timeline?.synchronization}
+              rangeNs={playbackState?.rangeNs}
+              currentNs={playbackState?.currentNs}
+              playing={playbackState?.playing}
+              onSeek={playbackController?.seek}
+              onPlayingChange={playbackController?.setPlaying}
+              onJumpToEnd={playbackController?.jumpToEnd}
+              accumulationSeconds={accumulationSeconds}
+              onAccumulationChange={onAccumulationChange}
+              onAccumulationCommit={onAccumulationCommit}
               className="scene-timeline"
             />
           ) : null}
@@ -440,6 +549,14 @@ function SpatialWorkspace({
               onMaximizedChange={(maximized) =>
                 observationLayout.setFloatingMaximized(source.id, maximized)}
               onActivate={() => observationLayout.activateFloatingSource(source.id)}
+              playback={recordedSource && playbackState ? {
+                currentSeconds: playbackState.currentNs / 1_000_000_000,
+                playing: playbackState.playing,
+              } : null}
+              prepareRecorded={!recordedSource || shouldPrepareRecordedSource(source.id)}
+              recordedSessionGate={recordedSessionGate}
+              recordedAdmissionKey={recordedSessionAdmission?.key ?? null}
+              onRecordedAdmissionChange={onRecordedAdmissionChange}
               onClose={() => {
                 if (observationLayout.pendingSourceIds.has(source.id)) return;
                 observationLayout.setFloatingMaximized(source.id, false);
@@ -447,6 +564,28 @@ function SpatialWorkspace({
               }}
             />
           )) : null}
+          {recordedSource ? (
+            <div className="recorded-session-preloaders" aria-hidden="true">
+              {mediaSources.filter((source) => (
+                source.delivery?.kind === "recorded-fmp4-manifest" &&
+                (pointCloudFocused || !observationLayout.visibleSourceIds.has(source.id)) &&
+                shouldPrepareRecordedSource(source.id)
+              )).map((source) => (
+                <ObservationMedia
+                  key={source.id}
+                  source={source}
+                  playback={playbackState ? {
+                    currentSeconds: playbackState.currentNs / 1_000_000_000,
+                    playing: false,
+                  } : null}
+                  prepareRecorded
+                  recordedSessionGate="loading"
+                  recordedAdmissionKey={recordedSessionAdmission?.key ?? null}
+                  onRecordedAdmissionChange={onRecordedAdmissionChange}
+                />
+              ))}
+            </div>
+          ) : null}
       </div>
 
       <div className="spatial-contract-strip">
@@ -470,6 +609,10 @@ function CameraSourceCard({
   onToggle,
   onFocus,
   onClose,
+  prepareRecorded,
+  recordedSessionGate,
+  recordedAdmissionKey,
+  onRecordedAdmissionChange,
 }: {
   source: ObservationSourceDescriptor;
   focused: boolean;
@@ -479,6 +622,13 @@ function CameraSourceCard({
   onToggle: () => void;
   onFocus: () => void;
   onClose: () => void;
+  prepareRecorded: boolean;
+  recordedSessionGate: RecordedAdmissionPhase;
+  recordedAdmissionKey: string | null;
+  onRecordedAdmissionChange: (
+    sourceId: string,
+    state: RecordedCameraAdmissionState,
+  ) => void;
 }) {
   const deliveryActive = Boolean(
     (source.delivery || source.previewUrl) &&
@@ -542,7 +692,13 @@ function CameraSourceCard({
         </div>
       </header>
       <div className="camera-slot__body">
-        <ObservationMedia source={source} />
+        <ObservationMedia
+          source={source}
+          prepareRecorded={prepareRecorded}
+          recordedSessionGate={recordedSessionGate}
+          recordedAdmissionKey={recordedAdmissionKey}
+          onRecordedAdmissionChange={onRecordedAdmissionChange}
+        />
       </div>
       <footer>
         <span>{source.description}</span>
@@ -552,13 +708,36 @@ function CameraSourceCard({
   );
 }
 
-function CamerasWorkspace({ definition, state, observationLayout }: WorkspaceRendererProps) {
+function CamerasWorkspace({
+  definition,
+  state,
+  observationLayout,
+  recordedReplay,
+  recordedSessionAdmission,
+}: WorkspaceRendererProps) {
   const sources = (state?.observationSources ?? []).filter(
     (source) => source.modality === "video" || source.modality === "image" || source.modality === "depth",
   );
   const focusedSource = sources.find((source) => source.id === observationLayout.focusedSourceId) ?? null;
   const timeline = state?.observationTimeline;
   const displayedSources = focusedSource ? [focusedSource] : sources;
+  const recordedSessionGate: RecordedAdmissionPhase = recordedReplay
+    ? recordedSessionAdmission?.phase ?? "loading"
+    : "ready";
+  const onRecordedAdmissionChange = useCallback((
+    sourceId: string,
+    next: RecordedCameraAdmissionState,
+  ) => {
+    if (!recordedSessionAdmission) return;
+    if (next.admissionKey !== recordedSessionAdmission.key) return;
+    recordedSessionAdmission.reportCamera(recordedSessionAdmission.key, sourceId, next);
+  }, [recordedSessionAdmission?.key, recordedSessionAdmission?.reportCamera]);
+  const shouldPrepareRecordedSource = useCallback((sourceId: string) => {
+    if (!recordedReplay) return true;
+    if (!recordedSessionAdmission) return false;
+    return recordedSessionAdmission.activeCameraSourceIds.has(sourceId) ||
+      recordedSessionAdmission.cameras[sourceId]?.phase === "ready";
+  }, [recordedReplay, recordedSessionAdmission]);
   return (
     <div className="standard-workspace cameras-workspace" data-focused={focusedSource ? "true" : undefined}>
       <WorkspaceLead definition={definition} note="Кадры не подменяются демонстрационным видео" />
@@ -587,6 +766,10 @@ function CamerasWorkspace({ definition, state, observationLayout }: WorkspaceRen
               observationLayout.setFocusedSourceId(null);
               void observationLayout.hideSource(source.id);
             }}
+            prepareRecorded={shouldPrepareRecordedSource(source.id)}
+            recordedSessionGate={recordedSessionGate}
+            recordedAdmissionKey={recordedSessionAdmission?.key ?? null}
+            onRecordedAdmissionChange={onRecordedAdmissionChange}
           />
         )) : (
           <div className="camera-grid__empty">
@@ -596,7 +779,25 @@ function CamerasWorkspace({ definition, state, observationLayout }: WorkspaceRen
           </div>
         )}
       </div>
-      <ObservationTimeline
+      {recordedReplay ? (
+        <div className="recorded-session-preloaders" aria-hidden="true">
+          {sources.filter((source) => (
+            !displayedSources.some(({ id }) => id === source.id) &&
+            source.delivery?.kind === "recorded-fmp4-manifest" &&
+            shouldPrepareRecordedSource(source.id)
+          )).map((source) => (
+            <ObservationMedia
+              key={source.id}
+              source={source}
+              prepareRecorded
+              recordedSessionGate="loading"
+              recordedAdmissionKey={recordedSessionAdmission?.key ?? null}
+              onRecordedAdmissionChange={onRecordedAdmissionChange}
+            />
+          ))}
+        </div>
+      ) : null}
+      {!recordedReplay || recordedSessionGate === "ready" ? <ObservationTimeline
         active={sources.some((source) =>
           source.availability === "streaming" &&
           (!source.activation || source.activation.selected))}
@@ -606,7 +807,7 @@ function CamerasWorkspace({ definition, state, observationLayout }: WorkspaceRen
         seekable={timeline?.seekable}
         synchronization={timeline?.synchronization}
         className="camera-timeline"
-      />
+      /> : null}
     </div>
   );
 }
diff --git a/apps/control-station/test/observationSessions.test.mjs b/apps/control-station/test/observationSessions.test.mjs
new file mode 100644
index 0000000..8d365ec
--- /dev/null
+++ b/apps/control-station/test/observationSessions.test.mjs
@@ -0,0 +1,832 @@
+import assert from "node:assert/strict";
+import { readFile } from "node:fs/promises";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let decodeObservationSessionCatalog;
+let decodeObservationSessionReplay;
+let decodeObservationSessionPreparation;
+let fetchObservationSessionCatalog;
+let replayObservationSession;
+let fetchObservationSessionPreparation;
+let cancelObservationSessionPreparation;
+let ObservationSessionApiError;
+let ObservationSessionContractError;
+let decodeObservationRecordedMediaManifest;
+let createObservationReplayCoordinator;
+let resolveObservationSessionReplay;
+let waitForObservationReplayPreparation;
+let storeObservationReplayPreparation;
+let loadObservationReplayPreparation;
+let observationSessionVisualState;
+let observationSessionVisualLabel;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  ({
+    decodeObservationSessionCatalog,
+    decodeObservationSessionReplay,
+    decodeObservationSessionPreparation,
+    fetchObservationSessionCatalog,
+    replayObservationSession,
+    fetchObservationSessionPreparation,
+    cancelObservationSessionPreparation,
+    ObservationSessionApiError,
+    ObservationSessionContractError,
+    decodeObservationRecordedMediaManifest,
+  } = await server.ssrLoadModule("/src/core/observation/sessionArchive.ts"));
+  ({
+    createObservationReplayCoordinator,
+    resolveObservationSessionReplay,
+    waitForObservationReplayPreparation,
+    storeObservationReplayPreparation,
+    loadObservationReplayPreparation,
+  } = await server.ssrLoadModule(
+    "/src/core/observation/useObservationSessions.ts",
+  ));
+  ({ observationSessionVisualState, observationSessionVisualLabel } = await server.ssrLoadModule(
+    "/src/components/ObservationSessionSelect.tsx",
+  ));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+function session(overrides = {}) {
+  return {
+    id: "20260716T205632Z_viewer_live",
+    label: "K1 · наблюдение 16 июля",
+    started_at_utc: "2026-07-16T20:56:32.635Z",
+    completed_at_utc: "2026-07-16T21:20:43.379Z",
+    status: "ready",
+    modalities: ["point-cloud", "pose"],
+    duration_seconds: 1_450.744,
+    replayable: true,
+    ...overrides,
+  };
+}
+
+function replay(overrides = {}) {
+  const sessionId = overrides.session_id ?? "session-20260716T205632Z";
+  const sourceUrl = overrides.source_url ??
+    `/api/v1/observation-sessions/${encodeURIComponent(sessionId)}/recording.rrd`;
+  const sha256 = overrides.sha256 ?? "a".repeat(64);
+  return {
+    schema_version: "missioncore.observation-session-replay/v2",
+    launch: {
+      kind: "rerun-recording",
+      session_id: sessionId,
+      source_url: sourceUrl,
+      viewer_source_url: overrides.viewer_source_url ?? `${sourceUrl}?generation=${sha256}`,
+      media_type: "application/vnd.rerun.rrd",
+      timeline: "session_time",
+      timeline_start_seconds: 0,
+      timeline_end_seconds: 1_450.744,
+      seekable: true,
+      byte_length: 123_456,
+      sha256,
+      playback: { speed: 1, loop: false },
+      media_sources: [],
+      ...overrides,
+    },
+  };
+}
+
+function preparation(overrides = {}) {
+  const sessionId = overrides.session_id ?? "session-20260716T205632Z";
+  return {
+    schema_version: "missioncore.observation-session-preparation/v1",
+    preparation: {
+      preparation_id: "prepare-20260717T131400Z",
+      session_id: sessionId,
+      state: "queued",
+      progress: null,
+      updated_at_utc: "2026-07-17T10:14:00Z",
+      status_url: `/api/v1/observation-sessions/${encodeURIComponent(sessionId)}/recording-preparation`,
+      cancellable: true,
+      ...overrides,
+    },
+  };
+}
+
+const preparationEtag = '"prepare-20260717T131400Z"';
+
+test("session catalog decodes canonical snake_case into a path-free camelCase model", () => {
+  const catalog = decodeObservationSessionCatalog({ items: [session()] });
+
+  assert.deepEqual(catalog.items, [{
+    id: "20260716T205632Z_viewer_live",
+    label: "K1 · наблюдение 16 июля",
+    startedAtUtc: "2026-07-16T20:56:32.635Z",
+    completedAtUtc: "2026-07-16T21:20:43.379Z",
+    status: "ready",
+    modalities: ["point-cloud", "pose"],
+    durationSeconds: 1_450.744,
+    replayable: true,
+    preparation: null,
+  }]);
+  assert.equal("raw_capture" in catalog.items[0], false);
+  assert.equal("path" in catalog.items[0], false);
+});
+
+test("session catalog exposes authoritative background preparation state", () => {
+  const catalog = decodeObservationSessionCatalog({
+    items: [session({
+      preparation: {
+        preparation_id: "prepare-catalog-1",
+        state: "exporting",
+        progress: 0.42,
+        updated_at_utc: "2026-07-17T10:14:00Z",
+        cancellable: true,
+        retryable: false,
+      },
+    })],
+  });
+  assert.deepEqual(catalog.items[0].preparation, {
+    preparationId: "prepare-catalog-1",
+    state: "exporting",
+    progress: 0.42,
+    updatedAtUtc: "2026-07-17T10:14:00Z",
+    cancellable: true,
+    retryable: false,
+    error: null,
+  });
+});
+
+test("saved-session rows use only authoritative ready, processing and error states", () => {
+  const makeDecoded = (state, overrides = {}) => decodeObservationSessionCatalog({
+    items: [session({
+      status: "interrupted",
+      preparation: state === null ? null : {
+        preparation_id: `prepare-${state}`,
+        state,
+        progress: state === "ready" ? 1 : 0.5,
+        updated_at_utc: "2026-07-17T10:14:00Z",
+        cancellable: ["queued", "validating", "exporting", "finalizing"].includes(state),
+        retryable: state === "failed",
+        ...(state === "failed" ? { error: "export failed" } : {}),
+      },
+      ...overrides,
+    })],
+  }).items[0];
+
+  assert.equal(observationSessionVisualState(makeDecoded("ready")), "ready");
+  for (const state of ["queued", "validating", "exporting", "finalizing"]) {
+    assert.equal(observationSessionVisualState(makeDecoded(state)), "processing");
+  }
+  assert.equal(observationSessionVisualState(makeDecoded("failed")), "error");
+  assert.equal(observationSessionVisualState(makeDecoded("cancelled")), "error");
+  assert.equal(
+    observationSessionVisualState(makeDecoded("failed", { status: "recording" })),
+    "error",
+  );
+  assert.equal(observationSessionVisualState(makeDecoded(null)), "error");
+  assert.equal(
+    observationSessionVisualState(makeDecoded(null, { status: "recording" })),
+    "processing",
+  );
+  assert.equal(
+    observationSessionVisualState(makeDecoded("ready", { replayable: false })),
+    "error",
+  );
+  assert.equal(
+    observationSessionVisualState(makeDecoded("ready"), { failed: true }),
+    "error",
+  );
+  assert.equal(
+    observationSessionVisualState(makeDecoded("failed"), { pending: true, failed: true }),
+    "error",
+  );
+  assert.equal(observationSessionVisualLabel("ready"), "Готово");
+  assert.equal(observationSessionVisualLabel("processing"), "Обработка");
+  assert.equal(observationSessionVisualLabel("error"), "Ошибка");
+});
+
+test("saved-session lamps use green or dim gray only, never warning or danger colors", async () => {
+  const css = await readFile(
+    new URL("../src/styles/observation-sessions.css", import.meta.url),
+    "utf8",
+  );
+  const start = css.indexOf(".observation-session-option i {");
+  const end = css.indexOf(".observation-session-option__state", start);
+  assert.notEqual(start, -1);
+  assert.notEqual(end, -1);
+  const lampRules = css.slice(start, end);
+  assert.match(lampRules, /data-session-visual-state="ready"[\s\S]*--nodedc-success-rgb/);
+  assert.match(lampRules, /data-session-visual-state="processing"[\s\S]*animation:/);
+  assert.match(lampRules, /data-session-visual-state="error"[\s\S]*--nodedc-text-muted/);
+  assert.match(lampRules, /data-session-visual-state="error"[\s\S]*opacity:\s*0\.48/);
+  assert.doesNotMatch(lampRules, /\b(?:warning|danger|yellow|red)\b/i);
+});
+
+test("session catalog sorts newest first and uses id as a deterministic tie-breaker", () => {
+  const catalog = decodeObservationSessionCatalog({
+    items: [
+      session({ id: "same-b", started_at_utc: "2026-07-16T19:00:00Z", completed_at_utc: null }),
+      session({ id: "newest", started_at_utc: "2026-07-17T00:00:00Z", completed_at_utc: null }),
+      session({ id: "same-a", started_at_utc: "2026-07-16T19:00:00Z", completed_at_utc: null }),
+    ],
+  });
+
+  assert.deepEqual(catalog.items.map(({ id }) => id), ["newest", "same-a", "same-b"]);
+});
+
+test("session catalog rejects raw storage fields, unsafe ids and duplicate ids", () => {
+  assert.throws(
+    () => decodeObservationSessionCatalog({
+      items: [session({ raw_capture: "sessions/private/mqtt.raw.k1mqtt" })],
+    }),
+    ObservationSessionContractError,
+  );
+  assert.throws(
+    () => decodeObservationSessionCatalog({ items: [session({ id: "../private" })] }),
+    ObservationSessionContractError,
+  );
+  assert.throws(
+    () => decodeObservationSessionCatalog({ items: [session(), session()] }),
+    /повторяющийся id/,
+  );
+});
+
+test("session catalog rejects invalid temporal, status and duration values", () => {
+  assert.throws(
+    () => decodeObservationSessionCatalog({
+      items: [session({ started_at_utc: "16 July 2026" })],
+    }),
+    /ISO-датой/,
+  );
+  assert.throws(
+    () => decodeObservationSessionCatalog({ items: [session({ status: "complete" })] }),
+    /неизвестное состояние/,
+  );
+  assert.throws(
+    () => decodeObservationSessionCatalog({ items: [session({ duration_seconds: -1 })] }),
+    /неотрицательным числом/,
+  );
+  assert.throws(
+    () => decodeObservationSessionCatalog({
+      items: [session({ completed_at_utc: "2026-07-16T19:00:00Z" })],
+    }),
+    /раньше времени начала/,
+  );
+});
+
+test("catalog API preserves HTTP detail without accepting a malformed success body", async () => {
+  await assert.rejects(
+    fetchObservationSessionCatalog({
+      fetcher: async () => new Response(JSON.stringify({ detail: "storage unavailable" }), {
+        status: 503,
+        headers: { "Content-Type": "application/json" },
+      }),
+    }),
+    (error) => error instanceof ObservationSessionApiError &&
+      error.status === 503 && error.message === "storage unavailable",
+  );
+
+  await assert.rejects(
+    fetchObservationSessionCatalog({
+      fetcher: async () => new Response(JSON.stringify({ items: "not-an-array" }), {
+        status: 200,
+        headers: { "Content-Type": "application/json" },
+      }),
+    }),
+    ObservationSessionContractError,
+  );
+});
+
+test("replay API accepts only a same-origin seekable recording descriptor", async () => {
+  const calls = [];
+  const launch = await replayObservationSession("session-20260716T205632Z", {
+    fetcher: async (input, init) => {
+      calls.push({ input: String(input), init });
+      return new Response(JSON.stringify(replay()), {
+        status: 200,
+        headers: { "Content-Type": "application/json" },
+      });
+    },
+  });
+
+  assert.equal(calls.length, 1);
+  assert.equal(calls[0].input, "/api/v1/observation-sessions/session-20260716T205632Z/replay");
+  assert.equal(calls[0].init.method, "POST");
+  assert.equal(launch.kind, "ready");
+  assert.equal(launch.launch.timeline, "session_time");
+  assert.equal(
+    launch.launch.sourceUrl,
+    "/api/v1/observation-sessions/session-20260716T205632Z/recording.rrd",
+  );
+  await assert.rejects(
+    replayObservationSession("../private", { fetcher: async () => new Response(null) }),
+    ObservationSessionContractError,
+  );
+});
+
+test("preparation contract is strict, session-scoped and same-origin", async () => {
+  const sessionId = "session-20260716T205632Z";
+  const decoded = decodeObservationSessionPreparation(preparation(), sessionId);
+  assert.equal(decoded.sessionId, sessionId);
+  assert.equal(decoded.state, "queued");
+  assert.equal(decoded.progress, null);
+
+  assert.throws(
+    () => decodeObservationSessionPreparation(
+      preparation({ status_url: "https://invalid.test/status" }),
+      sessionId,
+    ),
+    /канонический same-origin/,
+  );
+  assert.throws(
+    () => decodeObservationSessionPreparation(preparation({ debug_path: "/tmp/raw" }), sessionId),
+    /неизвестные поля/,
+  );
+  assert.throws(
+    () => decodeObservationSessionPreparation(preparation({ progress: 1.1 }), sessionId),
+    /недопустимое число/,
+  );
+  await assert.rejects(
+    replayObservationSession(sessionId, {
+      fetcher: async () => new Response(JSON.stringify(preparation()), {
+        status: 202,
+        headers: { "Content-Type": "application/json" },
+      }),
+    }),
+    /preparation ETag/,
+  );
+});
+
+test("202 preparation polls through explicit phases and reveals launch only when ready", async () => {
+  const sessionId = "session-20260716T205632Z";
+  const calls = [];
+  const phases = [];
+  let poll = 0;
+  let clock = 0;
+  let previousViewerMounted = true;
+  const launch = await resolveObservationSessionReplay(sessionId, {
+    signal: new AbortController().signal,
+    requestTimeoutMs: 1_000,
+    heartbeatStallMs: 5_000,
+    maximumWaitMs: 10_000,
+    initialPollIntervalMs: 50,
+    maximumPollIntervalMs: 50,
+    now: () => clock,
+    sleep: async (milliseconds) => {
+      assert.equal(previousViewerMounted, true);
+      clock += milliseconds;
+    },
+    onUpdate: (value) => {
+      assert.equal(previousViewerMounted, true);
+      phases.push([value.state, value.progress]);
+    },
+    fetcher: async (input, init) => {
+      calls.push([String(input), init.method, new Headers(init.headers).get("If-Match")]);
+      if (init.method === "POST") {
+        return new Response(JSON.stringify(preparation()), {
+          status: 202,
+          headers: { "Content-Type": "application/json", ETag: preparationEtag },
+        });
+      }
+      poll += 1;
+      if (poll === 1) {
+        return new Response(JSON.stringify(preparation({
+          state: "exporting",
+          progress: 0.5,
+          updated_at_utc: "2026-07-17T10:14:01Z",
+        })), {
+          status: 202,
+          headers: { "Content-Type": "application/json", ETag: preparationEtag },
+        });
+      }
+      return new Response(JSON.stringify(replay({ session_id: sessionId })), {
+        status: 200,
+        headers: { "Content-Type": "application/json", ETag: preparationEtag },
+      });
+    },
+  });
+  // This is the point where App is allowed to unmount the old viewer.
+  previousViewerMounted = false;
+  assert.equal(launch.sessionId, sessionId);
+  assert.deepEqual(phases, [["queued", null], ["exporting", 0.5]]);
+  assert.deepEqual(calls.map((entry) => entry[1]), ["POST", "GET", "GET"]);
+  assert.deepEqual(calls.map((entry) => entry[2]), [null, preparationEtag, preparationEtag]);
+});
+
+test("status-ready response must match the preparation ETag before launch is accepted", async () => {
+  const decoded = decodeObservationSessionPreparation(
+    preparation({ state: "finalizing", progress: 0.95 }),
+    "session-20260716T205632Z",
+  );
+  let receivedIfMatch;
+  await assert.rejects(
+    fetchObservationSessionPreparation(decoded, {
+      fetcher: async (_input, init) => {
+        receivedIfMatch = new Headers(init.headers).get("If-Match");
+        return new Response(JSON.stringify(replay()), {
+          status: 200,
+          headers: { "Content-Type": "application/json", ETag: '"replacement-job"' },
+        });
+      },
+    }),
+    /актуальный preparation ETag/,
+  );
+  assert.equal(receivedIfMatch, preparationEtag);
+});
+
+test("preparation cancellation is conditional on the same preparation ETag", async () => {
+  const decoded = decodeObservationSessionPreparation(
+    preparation({ state: "exporting", progress: 0.5 }),
+    "session-20260716T205632Z",
+  );
+  let request;
+  const result = await cancelObservationSessionPreparation(decoded, {
+    fetcher: async (input, init) => {
+      request = {
+        input: String(input),
+        method: init.method,
+        ifMatch: new Headers(init.headers).get("If-Match"),
+      };
+      return new Response(null, { status: 204 });
+    },
+  });
+  assert.equal(result, null);
+  assert.deepEqual(request, {
+    input: decoded.statusUrl,
+    method: "DELETE",
+    ifMatch: preparationEtag,
+  });
+});
+
+test("preparation polling fails explicitly when the server heartbeat stalls", async () => {
+  const decoded = decodeObservationSessionPreparation(
+    preparation({ state: "exporting", progress: 0.1 }),
+    "session-20260716T205632Z",
+  );
+  let clock = 0;
+  await assert.rejects(
+    waitForObservationReplayPreparation(decoded, {
+      signal: new AbortController().signal,
+      requestTimeoutMs: 1_000,
+      heartbeatStallMs: 250,
+      maximumWaitMs: 5_000,
+      initialPollIntervalMs: 150,
+      maximumPollIntervalMs: 150,
+      now: () => clock,
+      sleep: async (milliseconds) => { clock += milliseconds; },
+      fetcher: async () => new Response(JSON.stringify(preparation({
+        state: "exporting",
+        progress: 0.1,
+      })), {
+        status: 202,
+        headers: { "Content-Type": "application/json", ETag: preparationEtag },
+      }),
+    }),
+    /перестала обновляться/,
+  );
+});
+
+test("queued preparation can wait behind the bounded backend worker without false heartbeat failure", async () => {
+  const decoded = decodeObservationSessionPreparation(
+    preparation({ state: "queued", progress: 0 }),
+    "session-20260716T205632Z",
+  );
+  let clock = 0;
+  let polls = 0;
+  const launch = await waitForObservationReplayPreparation(decoded, {
+    signal: new AbortController().signal,
+    requestTimeoutMs: 1_000,
+    heartbeatStallMs: 250,
+    maximumWaitMs: 5_000,
+    initialPollIntervalMs: 150,
+    maximumPollIntervalMs: 150,
+    now: () => clock,
+    sleep: async (milliseconds) => { clock += milliseconds; },
+    fetcher: async () => {
+      polls += 1;
+      if (polls <= 2) {
+        return new Response(JSON.stringify(preparation({ state: "queued", progress: 0 })), {
+          status: 202,
+          headers: { "Content-Type": "application/json", ETag: preparationEtag },
+        });
+      }
+      return new Response(JSON.stringify(replay()), {
+        status: 200,
+        headers: { "Content-Type": "application/json", ETag: preparationEtag },
+      });
+    },
+  });
+  assert.equal(clock, 450);
+  assert.equal(launch.sessionId, "session-20260716T205632Z");
+});
+
+test("terminal preparation failure is explicit and retryable", async () => {
+  const sessionId = "session-20260716T205632Z";
+  const response = await replayObservationSession(sessionId, {
+    fetcher: async () => new Response(JSON.stringify(preparation({
+      state: "failed",
+      progress: 0.4,
+      cancellable: false,
+      retryable: true,
+      error: "Повреждён индекс исходной записи.",
+    })), {
+      status: 409,
+      headers: { "Content-Type": "application/json", ETag: preparationEtag },
+    }),
+  });
+  assert.equal(response.kind, "preparing");
+  assert.equal(response.preparation.retryable, true);
+  assert.equal(response.preparation.error, "Повреждён индекс исходной записи.");
+});
+
+test("pending preparation survives reload only through its strict canonical contract", () => {
+  const values = new Map();
+  const storage = {
+    get length() { return values.size; },
+    clear: () => values.clear(),
+    getItem: (key) => values.get(key) ?? null,
+    key: (index) => [...values.keys()][index] ?? null,
+    removeItem: (key) => values.delete(key),
+    setItem: (key, value) => values.set(key, String(value)),
+  };
+  const decoded = decodeObservationSessionPreparation(
+    preparation({ state: "exporting", progress: 0.7 }),
+    "session-20260716T205632Z",
+  );
+  storeObservationReplayPreparation(decoded, storage);
+  assert.deepEqual(loadObservationReplayPreparation(storage), decoded);
+
+  const key = storage.key(0);
+  storage.setItem(key, JSON.stringify({ ...preparation(), raw_path: "/private/raw" }));
+  assert.equal(loadObservationReplayPreparation(storage), null);
+  assert.equal(storage.length, 0);
+});
+
+test("replay API forwards cancellation and preserves AbortError semantics", async () => {
+  const controller = new AbortController();
+  let receivedSignal;
+  const pending = replayObservationSession("session-20260716T205632Z", {
+    signal: controller.signal,
+    fetcher: async (_input, init) => {
+      receivedSignal = init.signal;
+      return await new Promise((_resolve, reject) => {
+        init.signal.addEventListener("abort", () => {
+          reject(new DOMException("cancelled", "AbortError"));
+        }, { once: true });
+      });
+    },
+  });
+
+  controller.abort();
+  assert.equal(receivedSignal, controller.signal);
+  await assert.rejects(pending, (error) => error?.name === "AbortError");
+});
+
+test("replay coordinator makes rapid saved-session selection latest-request-wins", () => {
+  const coordinator = createObservationReplayCoordinator();
+  const first = coordinator.begin();
+  assert.equal(first.isCurrent(), true);
+
+  const second = coordinator.begin();
+  assert.equal(first.signal.aborted, true);
+  assert.equal(first.isCurrent(), false);
+  assert.equal(first.finish(), false);
+  assert.equal(second.isCurrent(), true);
+  assert.equal(second.finish(), true);
+  assert.equal(second.isCurrent(), false);
+
+  const third = coordinator.begin();
+  coordinator.cancel();
+  assert.equal(third.signal.aborted, true);
+  assert.equal(third.isCurrent(), false);
+});
+
+test("switching saved sessions aborts only local polling and never cancels shared backend work", async () => {
+  const hookSource = await readFile(
+    new URL("../src/core/observation/useObservationSessions.ts", import.meta.url),
+    "utf8",
+  );
+  const selectorSource = await readFile(
+    new URL("../src/components/ObservationSessionSelect.tsx", import.meta.url),
+    "utf8",
+  );
+  assert.doesNotMatch(hookSource, /cancelObservationSessionPreparation|method:\s*["']DELETE/);
+  assert.doesNotMatch(selectorSource, /cancelReplay|>\s*Отменить\s*</);
+});
+
+test("replay descriptor rejects path leaks, mismatched sessions and non-seekable data", () => {
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({ source_url: "file:///private/session.rrd" })),
+    /same-origin/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({ source_url: "/api/v1/observation-sessions/other/recording.rrd" })),
+    /same-origin/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({ seekable: false })),
+    /seekable/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({
+      viewer_source_url: "/api/v1/observation-sessions/session-20260716T205632Z/recording.rrd",
+    })),
+    /канонически привязан/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({
+      viewer_source_url: `https://foreign.test/recording.rrd?generation=${"a".repeat(64)}`,
+    })),
+    /канонически привязан/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({ raw_path: "/private/raw.k1mqtt" })),
+    /неизвестные поля/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({ byte_length: Number.MAX_SAFE_INTEGER + 1 })),
+    /недопустимое число/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({ playback: { speed: 101, loop: false } })),
+    /недопустимое число/,
+  );
+});
+
+test("replay decodes opaque recorded cameras and their same-origin fMP4 manifest", () => {
+  const sessionId = "session-20260716T205632Z";
+  const source = {
+    id: "recorded.camera.5a5a5a5a5a5a5a5a",
+    label: "Записанная камера 1",
+    modality: "video",
+    manifest_url: `/api/v1/observation-sessions/${sessionId}/media/recorded-video-5a5a5a5a5a5a5a5a/manifest`,
+    manifest_generation_sha256: "c".repeat(64),
+    byte_length: 3_266,
+    media_type: "video/mp4",
+    timeline_start_seconds: 0.25,
+    timeline_end_seconds: 20,
+    seekable: true,
+    synchronization: "host-arrival-best-effort",
+  };
+  const decoded = decodeObservationSessionReplay(replay({
+    session_id: sessionId,
+    timeline_end_seconds: 20,
+    media_sources: [source],
+  }));
+  assert.equal(
+    decoded.viewerSourceUrl,
+    `/api/v1/observation-sessions/${sessionId}/recording.rrd?generation=${"a".repeat(64)}`,
+  );
+  assert.equal(decoded.mediaSources.length, 1);
+  assert.equal(decoded.mediaSources[0].id, source.id);
+  assert.equal(decoded.mediaSources[0].manifestUrl, source.manifest_url);
+  assert.equal(
+    decoded.mediaSources[0].manifestGenerationSha256,
+    source.manifest_generation_sha256,
+  );
+
+  const manifest = decodeObservationRecordedMediaManifest({
+    schema_version: "missioncore.observation-recorded-media/v2",
+    source_id: source.id,
+    generation_sha256: "c".repeat(64),
+    byte_length: 3_266,
+    timeline_start_seconds: 0.25,
+    timeline_end_seconds: 20,
+    synchronization: "host-arrival-best-effort",
+    epochs: [{
+      ordinal: 1,
+      timeline_start_seconds: 0.25,
+      timeline_end_seconds: 20,
+      media_type: 'video/mp4; codecs="avc1.640028"',
+      init_url: source.manifest_url.replace("/manifest", "/epochs/1/init.mp4"),
+      init_byte_length: 128,
+      init_sha256: "a".repeat(64),
+      segment_count: 12,
+      segment_url_prefix: source.manifest_url.replace("/manifest", "/epochs/1/segments/"),
+      segments: Array.from({ length: 12 }, (_, index) => ({
+        sequence: index + 1,
+        url: source.manifest_url.replace("/manifest", `/epochs/1/segments/${index + 1}.m4s`),
+        byte_length: 256 + index,
+        sha256: "b".repeat(64),
+      })),
+    }],
+  }, decoded.mediaSources[0]);
+  assert.equal(manifest.epochs[0].segmentCount, 12);
+  assert.equal(manifest.epochs[0].segments.length, 12);
+  assert.equal(manifest.epochs[0].timelineStartSeconds, 0.25);
+  assert.throws(
+    () => decodeObservationRecordedMediaManifest({
+      ...{
+        schema_version: "missioncore.observation-recorded-media/v1",
+        source_id: source.id,
+        generation_sha256: "c".repeat(64),
+        byte_length: 3_266,
+        timeline_start_seconds: 0.25,
+        timeline_end_seconds: 20,
+        synchronization: "host-arrival-best-effort",
+        epochs: [],
+      },
+    }, decoded.mediaSources[0]),
+    /несовместим/,
+  );
+  assert.throws(
+    () => decodeObservationRecordedMediaManifest({
+      schema_version: "missioncore.observation-recorded-media/v2",
+      source_id: source.id,
+      generation_sha256: "c".repeat(64),
+      byte_length: 3_267,
+      timeline_start_seconds: 0.25,
+      timeline_end_seconds: 20,
+      synchronization: "host-arrival-best-effort",
+      epochs: [],
+    }, decoded.mediaSources[0]),
+    /несовместим|launch descriptor/,
+  );
+});
+
+test("recorded camera contracts reject foreign origins, path escapes and unknown fields", () => {
+  const sessionId = "session-20260716T205632Z";
+  const base = {
+    id: "recorded.camera.5a5a5a5a5a5a5a5a",
+    label: "Записанная камера 1",
+    modality: "video",
+    manifest_url: `/api/v1/observation-sessions/${sessionId}/media/recorded-video-5a5a5a5a5a5a5a5a/manifest`,
+    manifest_generation_sha256: "c".repeat(64),
+    byte_length: 384,
+    media_type: "video/mp4",
+    timeline_start_seconds: 0,
+    timeline_end_seconds: 20,
+    seekable: true,
+    synchronization: "host-arrival-best-effort",
+  };
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({
+      session_id: sessionId,
+      timeline_end_seconds: 20,
+      media_sources: [{ ...base, manifest_url: "https://invalid.test/private" }],
+    })),
+    /same-origin/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({
+      session_id: sessionId,
+      timeline_end_seconds: 20,
+      media_sources: [{ ...base, path: "/private/archive" }],
+    })),
+    /неизвестные поля/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({
+      session_id: sessionId,
+      timeline_end_seconds: 20,
+      media_sources: [{ ...base, manifest_generation_sha256: undefined }],
+    })),
+    /immutable generation/,
+  );
+  assert.throws(
+    () => decodeObservationSessionReplay(replay({
+      session_id: sessionId,
+      timeline_end_seconds: 20,
+      media_sources: [{ ...base, manifest_generation_sha256: "not-a-digest" }],
+    })),
+    /immutable generation/,
+  );
+  const decoded = decodeObservationSessionReplay(replay({
+    session_id: sessionId,
+    timeline_end_seconds: 20,
+    media_sources: [base],
+  }));
+  assert.throws(
+    () => decodeObservationRecordedMediaManifest({
+      schema_version: "missioncore.observation-recorded-media/v2",
+      source_id: base.id,
+      generation_sha256: "c".repeat(64),
+      byte_length: 384,
+      timeline_start_seconds: 0,
+      timeline_end_seconds: 20,
+      synchronization: "host-arrival-best-effort",
+      epochs: [{
+        ordinal: 1,
+        timeline_start_seconds: 0,
+        timeline_end_seconds: 20,
+        media_type: 'video/mp4; codecs="avc1.640028"',
+        init_url: "file:///private/init.mp4",
+        init_byte_length: 128,
+        init_sha256: "a".repeat(64),
+        segment_count: 1,
+        segment_url_prefix: "file:///private/segments/",
+        segments: [{
+          sequence: 1,
+          url: "file:///private/segments/1.m4s",
+          byte_length: 256,
+          sha256: "b".repeat(64),
+        }],
+      }],
+    }, decoded.mediaSources[0]),
+    /небезопасный API URL/,
+  );
+});
diff --git a/apps/control-station/test/observationSources.test.mjs b/apps/control-station/test/observationSources.test.mjs
index d147042..4df5859 100644
--- a/apps/control-station/test/observationSources.test.mjs
+++ b/apps/control-station/test/observationSources.test.mjs
@@ -1,6 +1,8 @@
 import assert from "node:assert/strict";
 import { after, before, test } from "node:test";
 
+import { createElement } from "react";
+import { renderToStaticMarkup } from "react-dom/server";
 import { createServer } from "vite";
 
 let server;
@@ -11,6 +13,20 @@ let shouldRestartObservationSource;
 let consumeCameraLeaseRetry;
 let resetCameraLeaseRetryBudget;
 let initialObservationWindowRect;
+let ObservationTimeline;
+let shouldCaptureWorkspacePointer;
+let normalizeTimelineRange;
+let timelineOffsetSeconds;
+let formatTimelineDuration;
+let normalizeAccumulationSeconds;
+let formatAccumulationDuration;
+let resolveRerunSourceUrl;
+let resolveRecordedBlueprintUrl;
+let fetchRecordedBlueprintRrd;
+let isRecordedPlaybackFullyBuffered;
+let recordedObservationSources;
+let selectRecordedMediaEpoch;
+let recordedMediaLocalTime;
 
 before(async () => {
   server = await createServer({
@@ -30,9 +46,32 @@ before(async () => {
   ({ consumeCameraLeaseRetry, resetCameraLeaseRetryBudget } = await server.ssrLoadModule(
     "/src/components/MseFmp4WebSocketPlayer.tsx",
   ));
-  ({ initialObservationWindowRect } = await server.ssrLoadModule(
+  ({ initialObservationWindowRect, shouldCaptureWorkspacePointer } = await server.ssrLoadModule(
     "/src/components/FloatingObservationWindow.tsx",
   ));
+  ({
+    ObservationTimeline,
+    normalizeTimelineRange,
+    timelineOffsetSeconds,
+    formatTimelineDuration,
+    normalizeAccumulationSeconds,
+    formatAccumulationDuration,
+  } =
+    await server.ssrLoadModule("/src/components/ObservationTimeline.tsx"));
+  ({
+    resolveRerunSourceUrl,
+    resolveRecordedBlueprintUrl,
+    fetchRecordedBlueprintRrd,
+    isRecordedPlaybackFullyBuffered,
+  } = await server.ssrLoadModule(
+    "/src/components/RerunViewport.tsx",
+  ));
+  ({ recordedObservationSources } = await server.ssrLoadModule(
+    "/src/core/observation/recordedObservationSources.ts",
+  ));
+  ({ selectRecordedMediaEpoch, recordedMediaLocalTime } = await server.ssrLoadModule(
+    "/src/components/RecordedFmp4Player.tsx",
+  ));
 });
 
 test("observation camera windows tile from the bottom-right above the live timeline", () => {
@@ -75,6 +114,251 @@ test("observation camera tiling remains in bounds on a constrained viewport", ()
   assert.ok(rects[1].y + rects[1].height <= rects[0].y);
 });
 
+test("floating observation interaction captures resize and movable header pointers", () => {
+  const target = (matches) => ({ closest: (selector) => matches.includes(selector) });
+  assert.equal(
+    shouldCaptureWorkspacePointer(0, target([".nodedc-workspace-window__resize"])),
+    true,
+  );
+  assert.equal(
+    shouldCaptureWorkspacePointer(0, target([".nodedc-workspace-window__head"])),
+    true,
+  );
+  assert.equal(
+    shouldCaptureWorkspacePointer(
+      0,
+      target([".nodedc-workspace-window__head", "button, input, select, textarea, a"]),
+    ),
+    false,
+  );
+  assert.equal(
+    shouldCaptureWorkspacePointer(2, target([".nodedc-workspace-window__resize"])),
+    false,
+  );
+});
+
+test("recorded observation timeline clamps relative seek time without epoch precision in the UI", () => {
+  const range = normalizeTimelineRange({
+    min: 0,
+    max: 12_500_000_000,
+  });
+  assert.ok(range);
+  assert.equal(timelineOffsetSeconds(range, range.min + 2_250_000_000), 2.25);
+  assert.equal(timelineOffsetSeconds(range, range.min - 1), 0);
+  assert.equal(timelineOffsetSeconds(range, range.max + 1), 12.5);
+  assert.equal(formatTimelineDuration(62.125), "01:02.125");
+});
+
+test("recorded observation timeline rejects empty and non-finite ranges", () => {
+  assert.equal(normalizeTimelineRange(null), null);
+  assert.equal(normalizeTimelineRange({ min: 10, max: 10 }), null);
+  assert.equal(normalizeTimelineRange({ min: Number.NaN, max: 10 }), null);
+});
+
+test("accumulation control normalizes UI values and distinguishes a single frame", () => {
+  assert.equal(normalizeAccumulationSeconds(-3), 0);
+  assert.equal(normalizeAccumulationSeconds(12.6), 13);
+  assert.equal(normalizeAccumulationSeconds(999), 120);
+  assert.equal(normalizeAccumulationSeconds(Number.NaN), 0);
+  assert.equal(formatAccumulationDuration(0), "Кадр");
+  assert.equal(formatAccumulationDuration(12), "12 с");
+});
+
+test("spatial timeline renders synchronized accumulation and playback controls", () => {
+  const markup = renderToStaticMarkup(createElement(ObservationTimeline, {
+    active: true,
+    sourceCount: 2,
+    mode: "recorded",
+    seekable: true,
+    rangeNs: { min: 0, max: 20_000_000_000 },
+    currentNs: 5_000_000_000,
+    accumulationSeconds: 12,
+    onAccumulationChange: () => undefined,
+    onAccumulationCommit: () => undefined,
+    onSeek: () => undefined,
+  }));
+
+  assert.match(markup, /data-accumulation="true"/);
+  assert.match(markup, /Накопление/);
+  assert.match(markup, /aria-label="Окно накопления облака точек"/);
+  assert.match(markup, /aria-valuetext="12 с"/);
+  assert.match(markup, /aria-label="Позиция воспроизведения"/);
+  assert.equal((markup.match(/type="range"/g) ?? []).length, 2);
+});
+
+test("Rerun expands only root-relative session recordings onto the current origin", () => {
+  assert.equal(
+    resolveRerunSourceUrl(
+      " /api/v1/observation-sessions/session-1/recording.rrd ",
+      "http://127.0.0.1:5174",
+    ),
+    "http://127.0.0.1:5174/api/v1/observation-sessions/session-1/recording.rrd",
+  );
+  assert.equal(
+    resolveRerunSourceUrl("rerun+http://127.0.0.1:9877/proxy", "http://127.0.0.1:5174"),
+    "rerun+http://127.0.0.1:9877/proxy",
+  );
+  assert.equal(
+    resolveRerunSourceUrl("//different-authority.invalid/session.rrd", "http://127.0.0.1:5174"),
+    "//different-authority.invalid/session.rrd",
+  );
+});
+
+test("recorded blueprint endpoint is derived only from canonical same-origin RRD sources", () => {
+  assert.equal(
+    resolveRecordedBlueprintUrl(
+      "/api/v1/observation-sessions/session-1/recording.rrd",
+      "http://127.0.0.1:5174",
+    ),
+    "http://127.0.0.1:5174/api/v1/observation-sessions/session-1/blueprint.rrd",
+  );
+  assert.equal(
+    resolveRecordedBlueprintUrl(
+      "https://outside.invalid/api/v1/observation-sessions/session-1/recording.rrd",
+      "http://127.0.0.1:5174",
+    ),
+    null,
+  );
+  assert.equal(
+    resolveRecordedBlueprintUrl(
+      "/api/v1/observation-sessions/../recording.rrd",
+      "http://127.0.0.1:5174",
+    ),
+    null,
+  );
+});
+
+test("recorded replay becomes ready only after the complete declared timeline is buffered", () => {
+  assert.equal(isRecordedPlaybackFullyBuffered(null, 20), false);
+  assert.equal(
+    isRecordedPlaybackFullyBuffered({ min: 0, max: 19_500_000_000 }, 20),
+    false,
+  );
+  assert.equal(
+    isRecordedPlaybackFullyBuffered({ min: 0, max: 19_999_500_000 }, 20),
+    true,
+  );
+  assert.equal(
+    isRecordedPlaybackFullyBuffered({ min: 0, max: 1 }, undefined),
+    true,
+  );
+  assert.equal(
+    isRecordedPlaybackFullyBuffered({ min: 0, max: 20_000_000_000 }, Number.NaN),
+    false,
+  );
+});
+
+test("recorded blueprint fetch is bounded, strict and sends only display settings", async () => {
+  const calls = [];
+  const payload = Uint8Array.from([0x52, 0x52, 0x46, 0x32, 0x01]);
+  const result = await fetchRecordedBlueprintRrd(
+    "http://127.0.0.1:5174/api/v1/observation-sessions/session-1/blueprint.rrd",
+    {
+      accumulationSeconds: 24,
+      showGrid: false,
+      showPoints: true,
+      showTrajectory: false,
+      pointSize: 4.5,
+      palette: "custom",
+      customColor: "#35d7c1",
+    },
+    { applicationId: "nodedc_mission_core_recorded", recordingId: "recording-001" },
+    {
+      origin: "http://127.0.0.1:5174",
+      fetcher: async (input, init) => {
+        calls.push({ input: String(input), init, body: JSON.parse(String(init.body)) });
+        return new Response(payload, {
+          status: 200,
+          headers: { "Content-Type": "application/vnd.rerun.rrd" },
+        });
+      },
+    },
+  );
+  assert.deepEqual([...result], [...payload]);
+  assert.equal(calls[0].init.method, "POST");
+  assert.equal(calls[0].init.credentials, "same-origin");
+  assert.deepEqual(calls[0].body, {
+    application_id: "nodedc_mission_core_recorded",
+    recording_id: "recording-001",
+    accumulation_seconds: 24,
+    show_grid: false,
+    show_points: true,
+    show_trajectory: false,
+    point_size: 4.5,
+    palette: "custom",
+    custom_color: "#35d7c1",
+  });
+
+  await assert.rejects(
+    fetchRecordedBlueprintRrd(
+      "https://outside.invalid/api/v1/observation-sessions/session-1/blueprint.rrd",
+      {
+        accumulationSeconds: 24,
+        showGrid: false,
+        showPoints: true,
+        showTrajectory: false,
+        pointSize: 4.5,
+        palette: "custom",
+        customColor: "#35d7c1",
+      },
+      { applicationId: "nodedc_mission_core_recorded", recordingId: "recording-001" },
+      { origin: "http://127.0.0.1:5174", fetcher: async () => new Response(payload) },
+    ),
+    /Unsafe recorded blueprint request/,
+  );
+});
+
+test("recorded replay creates an isolated source catalog without live device bindings", () => {
+  const sources = recordedObservationSources({
+    kind: "rerun-recording",
+    sessionId: "session-1",
+    sourceUrl: "/api/v1/observation-sessions/session-1/recording.rrd",
+    viewerSourceUrl: `/api/v1/observation-sessions/session-1/recording.rrd?generation=${"a".repeat(64)}`,
+    mediaType: "application/vnd.rerun.rrd",
+    timeline: "session_time",
+    timelineStartSeconds: 0,
+    timelineEndSeconds: 20,
+    seekable: true,
+    byteLength: 123,
+    sha256: "a".repeat(64),
+    playback: { speed: 1, loop: false },
+    mediaSources: [{
+      id: "recorded.camera.abc123",
+      label: "Записанная камера 1",
+      modality: "video",
+      manifestUrl: "/api/v1/observation-sessions/session-1/media/recorded-video-abc123/manifest",
+      manifestGenerationSha256: "c".repeat(64),
+      byteLength: 1_024,
+      mediaType: "video/mp4",
+      timelineStartSeconds: 0.25,
+      timelineEndSeconds: 20,
+      seekable: true,
+      synchronization: "host-arrival-best-effort",
+    }],
+  });
+  assert.deepEqual(sources.map(({ modality }) => modality), ["point-cloud", "video"]);
+  assert.equal(sources[1].delivery.kind, "recorded-fmp4-manifest");
+  assert.equal(sources[1].delivery.manifestGenerationSha256, "c".repeat(64));
+  assert.deepEqual(sources[1].binding, {});
+  assert.equal(sources.some(({ provider }) => provider.pluginId.includes("xgrids")), false);
+  assert.equal(JSON.stringify(sources).includes("192.168"), false);
+});
+
+test("recorded camera epoch selection and shared-clock offset are deterministic", () => {
+  const epochs = [
+    { ordinal: 1, timelineStartSeconds: 0.25, timelineEndSeconds: 9 },
+    { ordinal: 2, timelineStartSeconds: 10, timelineEndSeconds: 20 },
+  ];
+  assert.equal(selectRecordedMediaEpoch(epochs, 0), null);
+  assert.equal(selectRecordedMediaEpoch(epochs, 0.25).ordinal, 1);
+  assert.equal(selectRecordedMediaEpoch(epochs, 9), epochs[0]);
+  assert.equal(selectRecordedMediaEpoch(epochs, 9.9), null);
+  assert.equal(selectRecordedMediaEpoch(epochs, 10).ordinal, 2);
+  assert.equal(recordedMediaLocalTime(10, 12.5), 2.5);
+  assert.equal(recordedMediaLocalTime(10, 8), 0);
+  assert.equal(recordedMediaLocalTime(10, 30, 4), 4);
+});
+
 after(async () => {
   await server?.close();
 });
diff --git a/apps/control-station/test/recordedCameraBuffering.test.mjs b/apps/control-station/test/recordedCameraBuffering.test.mjs
new file mode 100644
index 0000000..f7e5bfe
--- /dev/null
+++ b/apps/control-station/test/recordedCameraBuffering.test.mjs
@@ -0,0 +1,303 @@
+import assert from "node:assert/strict";
+import { createHash } from "node:crypto";
+import { readFile } from "node:fs/promises";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let fetchVerifiedRecordedMediaArchive;
+let recordedMediaPresentationState;
+let recordedMediaSeekableCoverage;
+let appendRecordedMediaBuffer;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  ({
+    fetchVerifiedRecordedMediaArchive,
+    recordedMediaPresentationState,
+    recordedMediaSeekableCoverage,
+    appendRecordedMediaBuffer,
+  } = await server.ssrLoadModule("/src/components/RecordedFmp4Player.tsx"));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+function digest(payload) {
+  return createHash("sha256").update(payload).digest("hex");
+}
+
+function fixture() {
+  const manifestUrl = "/api/v1/observation-sessions/session-1/media/camera-1/manifest";
+  const init = Buffer.from("canonical-init");
+  const first = Buffer.from("canonical-first-fragment");
+  const second = Buffer.from("canonical-second-fragment");
+  const generation = "a".repeat(64);
+  const segmentPrefix = manifestUrl.replace("/manifest", "/epochs/1/segments/");
+  const manifest = {
+    schema_version: "missioncore.observation-recorded-media/v2",
+    source_id: "recorded.camera.camera-1",
+    generation_sha256: generation,
+    byte_length: init.byteLength + first.byteLength + second.byteLength,
+    timeline_start_seconds: 0,
+    timeline_end_seconds: 20,
+    synchronization: "host-arrival-best-effort",
+    epochs: [{
+      ordinal: 1,
+      timeline_start_seconds: 0,
+      timeline_end_seconds: 20,
+      media_type: 'video/mp4; codecs="avc1.640028"',
+      init_url: manifestUrl.replace("/manifest", "/epochs/1/init.mp4"),
+      init_byte_length: init.byteLength,
+      init_sha256: digest(init),
+      segment_count: 2,
+      segment_url_prefix: segmentPrefix,
+      segments: [first, second].map((payload, index) => ({
+        sequence: index + 1,
+        url: `${segmentPrefix}${index + 1}.m4s`,
+        byte_length: payload.byteLength,
+        sha256: digest(payload),
+      })),
+    }],
+  };
+  const source = {
+    id: manifest.source_id,
+    label: "Записанная камера",
+    modality: "video",
+    manifestUrl,
+    manifestGenerationSha256: generation,
+    byteLength: manifest.byte_length,
+    mediaType: "video/mp4",
+    timelineStartSeconds: 0,
+    timelineEndSeconds: 20,
+    seekable: true,
+    synchronization: "host-arrival-best-effort",
+  };
+  return { source, manifest, generation, init, first, second };
+}
+
+function jsonResponse(payload, generation) {
+  return new Response(JSON.stringify(payload), {
+    status: 200,
+    headers: {
+      "Content-Type": "application/json",
+      ETag: `"sha256:${generation}"`,
+    },
+  });
+}
+
+function mediaResponse(payload, sha = digest(payload), length = payload.byteLength) {
+  return new Response(payload, {
+    status: 200,
+    headers: {
+      "Content-Length": String(length),
+      ETag: `"sha256:${sha}"`,
+    },
+  });
+}
+
+function deferred() {
+  let resolve;
+  let reject;
+  const promise = new Promise((resolvePromise, rejectPromise) => {
+    resolve = resolvePromise;
+    reject = rejectPromise;
+  });
+  return { promise, resolve, reject };
+}
+
+async function flushAsync() {
+  await new Promise((resolve) => setTimeout(resolve, 0));
+  await new Promise((resolve) => setTimeout(resolve, 0));
+}
+
+test("recorded camera archive stays pending until every canonical byte is verified", async () => {
+  const { source, manifest, generation, init, first, second } = fixture();
+  const finalSegment = deferred();
+  const requested = [];
+  let manifestRequests = 0;
+  const fetcher = async (input, request = {}) => {
+    const url = String(input);
+    requested.push(url);
+    const headers = new Headers(request.headers);
+    if (url === source.manifestUrl) {
+      manifestRequests += 1;
+      assert.equal(headers.get("If-Match"), `"sha256:${generation}"`);
+      return jsonResponse(manifest, generation);
+    }
+    const epoch = manifest.epochs[0];
+    if (url === epoch.init_url) {
+      assert.equal(headers.get("If-Match"), `"sha256:${epoch.init_sha256}"`);
+      return mediaResponse(init);
+    }
+    if (url === epoch.segments[0].url) return mediaResponse(first);
+    if (url === epoch.segments[1].url) return finalSegment.promise;
+    throw new Error(`Unexpected URL ${url}`);
+  };
+
+  let settled = false;
+  const archivePromise = fetchVerifiedRecordedMediaArchive(source, { fetcher })
+    .then((archive) => {
+      settled = true;
+      return archive;
+    });
+  await flushAsync();
+
+  assert.equal(settled, false, "init and a partial segment prefix must not publish the camera");
+  assert.deepEqual(requested.slice(0, 4), [
+    source.manifestUrl,
+    manifest.epochs[0].init_url,
+    manifest.epochs[0].segments[0].url,
+    manifest.epochs[0].segments[1].url,
+  ]);
+
+  finalSegment.resolve(mediaResponse(second));
+  const archive = await archivePromise;
+  assert.equal(manifestRequests, 2, "the immutable generation is revalidated after transfer");
+  assert.equal(archive.byteLength, init.byteLength + first.byteLength + second.byteLength);
+  assert.equal(archive.epochs[0].segments.length, 2);
+});
+
+test("first camera manifest request is launch-generation bound and rejects replacement", async () => {
+  const { source, manifest, generation } = fixture();
+  const replacementGeneration = "d".repeat(64);
+  let requests = 0;
+  const fetcher = async (input, request = {}) => {
+    requests += 1;
+    assert.equal(String(input), source.manifestUrl);
+    assert.equal(
+      new Headers(request.headers).get("If-Match"),
+      `"sha256:${generation}"`,
+    );
+    return jsonResponse(
+      { ...manifest, generation_sha256: replacementGeneration },
+      replacementGeneration,
+    );
+  };
+
+  await assert.rejects(
+    fetchVerifiedRecordedMediaArchive(source, { fetcher }),
+    /несовместим|заменён/,
+  );
+  assert.equal(requests, 1);
+});
+
+test("recorded camera archive fails closed on truncation despite plausible headers", async () => {
+  const { source, manifest, generation, init, first, second } = fixture();
+  const fetcher = async (input) => {
+    const url = String(input);
+    if (url === source.manifestUrl) return jsonResponse(manifest, generation);
+    const epoch = manifest.epochs[0];
+    if (url === epoch.init_url) return mediaResponse(init);
+    if (url === epoch.segments[0].url) return mediaResponse(first);
+    if (url === epoch.segments[1].url) {
+      return mediaResponse(second.subarray(0, second.byteLength - 1), digest(second), second.byteLength);
+    }
+    throw new Error(`Unexpected URL ${url}`);
+  };
+
+  await assert.rejects(
+    fetchVerifiedRecordedMediaArchive(source, { fetcher }),
+    /усечён/,
+  );
+});
+
+test("recorded camera archive fails closed when bytes are replaced under an old ETag", async () => {
+  const { source, manifest, generation, init, first, second } = fixture();
+  const replacement = Buffer.from(second.map((value) => value ^ 0xff));
+  assert.equal(replacement.byteLength, second.byteLength);
+  const fetcher = async (input) => {
+    const url = String(input);
+    if (url === source.manifestUrl) return jsonResponse(manifest, generation);
+    const epoch = manifest.epochs[0];
+    if (url === epoch.init_url) return mediaResponse(init);
+    if (url === epoch.segments[0].url) return mediaResponse(first);
+    if (url === epoch.segments[1].url) {
+      return mediaResponse(replacement, digest(second), second.byteLength);
+    }
+    throw new Error(`Unexpected URL ${url}`);
+  };
+
+  await assert.rejects(
+    fetchVerifiedRecordedMediaArchive(source, { fetcher }),
+    /SHA-256/,
+  );
+});
+
+test("camera presentation gate opens only for the completely appended selected epoch", () => {
+  assert.equal(recordedMediaPresentationState("loading", null, "g1", false), "loading");
+  assert.equal(recordedMediaPresentationState("ready", null, "g1", false), "loading");
+  assert.equal(recordedMediaPresentationState("ready", "g2", "g1", false), "loading");
+  assert.equal(recordedMediaPresentationState("ready", "g1", "g1", false), "ready");
+  assert.equal(recordedMediaPresentationState("ready", "g1", null, true), "waiting");
+  assert.equal(recordedMediaPresentationState("error", "g1", "g1", false), "error");
+  assert.equal(recordedMediaPresentationState("ready", "g1", "g1", false, "loading"), "loading");
+  assert.equal(recordedMediaPresentationState("ready", "g1", null, true, "loading"), "loading");
+  assert.equal(recordedMediaPresentationState("ready", "g1", "g1", false, "error"), "error");
+});
+
+test("decoded duration and seekable range cover the complete declared epoch", () => {
+  assert.equal(recordedMediaSeekableCoverage(20, 20, 20), true);
+  assert.equal(recordedMediaSeekableCoverage(19, 19, 20), true);
+  assert.equal(recordedMediaSeekableCoverage(18.99, 20, 20), false);
+  assert.equal(recordedMediaSeekableCoverage(20, 18.99, 20), false);
+  assert.equal(recordedMediaSeekableCoverage(20, 20, 20, 1, 1), true);
+  assert.equal(recordedMediaSeekableCoverage(20, 20, 20, 1, 1.01), false);
+});
+
+test("aborting SourceBuffer append removes every temporary listener", async () => {
+  const listeners = new Map();
+  const sourceBuffer = {
+    addEventListener(type, listener) {
+      const bucket = listeners.get(type) ?? new Set();
+      bucket.add(listener);
+      listeners.set(type, bucket);
+    },
+    removeEventListener(type, listener) {
+      listeners.get(type)?.delete(listener);
+    },
+    appendBuffer() {},
+  };
+  const abort = new AbortController();
+  const pending = appendRecordedMediaBuffer(
+    sourceBuffer,
+    new ArrayBuffer(8),
+    abort.signal,
+  );
+  assert.equal(listeners.get("updateend")?.size, 1);
+  assert.equal(listeners.get("error")?.size, 1);
+  abort.abort();
+  await assert.rejects(pending, (error) => error?.name === "AbortError");
+  assert.equal(listeners.get("updateend")?.size, 0);
+  assert.equal(listeners.get("error")?.size, 0);
+});
+
+test("verified camera archives remain immutable for safe player remount", async () => {
+  const source = await readFile(
+    new URL("../src/components/RecordedFmp4Player.tsx", import.meta.url),
+    "utf8",
+  );
+  assert.doesNotMatch(source, /\.init\s*=\s*new ArrayBuffer/);
+  assert.doesNotMatch(source, /\.segments\.length\s*=\s*0/);
+});
+
+test("loading and error overlays fully conceal recorded camera pixels", async () => {
+  const css = await readFile(
+    new URL("../src/styles/observation.css", import.meta.url),
+    "utf8",
+  );
+  assert.match(
+    css,
+    /\.recorded-media-player:not\(\[data-state="ready"\]\) \.observation-media__asset\s*\{[^}]*visibility:\s*hidden/s,
+  );
+  assert.match(
+    css,
+    /\.recorded-media-player__notice\s*\{[^}]*inset:\s*0;[^}]*background:\s*#070809/s,
+  );
+});
diff --git a/apps/control-station/test/recordedSessionAdmission.test.mjs b/apps/control-station/test/recordedSessionAdmission.test.mjs
new file mode 100644
index 0000000..2bc4ae9
--- /dev/null
+++ b/apps/control-station/test/recordedSessionAdmission.test.mjs
@@ -0,0 +1,175 @@
+import assert from "node:assert/strict";
+import { readFile } from "node:fs/promises";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let admission;
+let rerunPresentationStatus;
+let recordedMediaPresentationState;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  admission = await server.ssrLoadModule(
+    "/src/core/observation/recordedSessionAdmission.ts",
+  );
+  ({ rerunPresentationStatus } = await server.ssrLoadModule(
+    "/src/components/RerunViewport.tsx",
+  ));
+  ({ recordedMediaPresentationState } = await server.ssrLoadModule(
+    "/src/components/RecordedFmp4Player.tsx",
+  ));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+function camera(phase, byteLength = 1_024) {
+  return { phase, byteLength, message: null };
+}
+
+test("recorded session admits RRD and every declared camera as one atomic generation", () => {
+  const ids = ["camera.left", "camera.right"];
+  const oneCamera = {
+    "camera.left": camera("ready"),
+    "camera.right": camera("pending"),
+  };
+  const partialGate = admission.recordedSessionAdmissionPhase("ready", ids, oneCamera);
+  assert.equal(partialGate, "loading");
+  assert.equal(rerunPresentationStatus("ready", partialGate, true), "loading");
+  assert.equal(
+    recordedMediaPresentationState("ready", "generation", "generation", false, partialGate),
+    "loading",
+  );
+
+  const completeGate = admission.recordedSessionAdmissionPhase("ready", ids, {
+    ...oneCamera,
+    "camera.right": camera("ready"),
+  });
+  assert.equal(completeGate, "ready");
+  assert.equal(rerunPresentationStatus("ready", completeGate, true), "ready");
+  assert.equal(
+    recordedMediaPresentationState("ready", "generation", "generation", false, completeGate),
+    "ready",
+  );
+});
+
+test("any RRD or camera failure closes the complete recorded session", () => {
+  const ids = ["camera.left", "camera.right"];
+  const cameras = {
+    "camera.left": camera("ready"),
+    "camera.right": camera("error"),
+  };
+  assert.equal(admission.recordedSessionAdmissionPhase("ready", ids, cameras), "error");
+  assert.equal(admission.recordedSessionAdmissionPhase("error", ids, {
+    ...cameras,
+    "camera.right": camera("ready"),
+  }), "error");
+  assert.equal(rerunPresentationStatus("ready", "error", true), "error");
+  assert.equal(
+    recordedMediaPresentationState("ready", "generation", "generation", false, "error"),
+    "error",
+  );
+});
+
+test("camera admission enforces independent 16/128/512 MiB limits before fetching", () => {
+  const {
+    MAX_RECORDED_CAMERA_SOURCES,
+    MAX_RECORDED_MEDIA_SOURCE_BYTES,
+    MAX_RECORDED_SESSION_CAMERA_BYTES,
+    recordedCameraDescriptorPreflight,
+  } = admission;
+  assert.equal(MAX_RECORDED_CAMERA_SOURCES, 16);
+  assert.equal(MAX_RECORDED_MEDIA_SOURCE_BYTES, 128 * 1024 * 1024);
+  assert.equal(MAX_RECORDED_SESSION_CAMERA_BYTES, 512 * 1024 * 1024);
+  assert.equal(recordedCameraDescriptorPreflight(
+    Array.from({ length: 4 }, (_, index) => ({
+      id: `camera.${index}`,
+      byteLength: MAX_RECORDED_MEDIA_SOURCE_BYTES,
+    })),
+  ), "ready");
+  assert.equal(recordedCameraDescriptorPreflight(
+    Array.from({ length: 17 }, (_, index) => ({ id: `camera.${index}`, byteLength: 1 })),
+  ), "error");
+  assert.equal(recordedCameraDescriptorPreflight([
+    { id: "camera.large", byteLength: MAX_RECORDED_MEDIA_SOURCE_BYTES + 1 },
+  ]), "error");
+  assert.equal(recordedCameraDescriptorPreflight(
+    Array.from({ length: 5 }, (_, index) => ({
+      id: `camera.${index}`,
+      byteLength: 110 * 1024 * 1024,
+    })),
+  ), "error");
+  assert.equal(recordedCameraDescriptorPreflight([
+    { id: "camera.duplicate", byteLength: 1 },
+    { id: "camera.duplicate", byteLength: 1 },
+  ]), "error");
+});
+
+test("camera preparation remains single-flight and retains the loading permit", () => {
+  const ids = ["camera.first", "camera.preferred"];
+  const cameras = {
+    "camera.first": camera("loading"),
+    "camera.preferred": camera("pending"),
+  };
+  assert.deepEqual(
+    admission.nextRecordedCameraPreparationIds(
+      ids,
+      cameras,
+      new Set(["camera.preferred"]),
+    ),
+    ["camera.first"],
+  );
+  assert.deepEqual(
+    admission.nextRecordedCameraPreparationIds(ids, {
+      ...cameras,
+      "camera.first": camera("ready"),
+    }),
+    ["camera.preferred"],
+  );
+});
+
+test("new render workers close readiness and stale callbacks cannot reopen it", () => {
+  const ready = { ...camera("ready"), workerGeneration: 1 };
+  const remounted = admission.mergeRecordedCameraAdmission(ready, {
+    ...camera("loading"),
+    workerGeneration: 2,
+  });
+  assert.equal(remounted.phase, "loading");
+  assert.equal(remounted.workerGeneration, 2);
+  assert.equal(admission.mergeRecordedCameraAdmission(remounted, {
+    ...camera("ready"),
+    workerGeneration: 1,
+  }), remounted);
+  const admitted = admission.mergeRecordedCameraAdmission(remounted, {
+    ...camera("ready"),
+    workerGeneration: 2,
+  });
+  assert.equal(admitted.phase, "ready");
+  const failed = admission.mergeRecordedCameraAdmission(admitted, {
+    ...camera("error"),
+    workerGeneration: 2,
+  });
+  assert.equal(failed.phase, "error");
+  assert.equal(admission.mergeRecordedCameraAdmission(failed, {
+    ...camera("loading"),
+    workerGeneration: 3,
+  }), failed);
+});
+
+test("recorded player is not mounted for a camera without a scheduler permit", async () => {
+  const source = await readFile(
+    new URL("../src/components/ObservationSources.tsx", import.meta.url),
+    "utf8",
+  );
+  const placeholder = source.indexOf("if (!prepareRecorded)");
+  const player = source.indexOf("<RecordedFmp4Player", placeholder);
+  assert.ok(placeholder >= 0 && player > placeholder);
+  assert.match(source.slice(placeholder, player), /return\s*\(/);
+});
diff --git a/apps/control-station/test/rerunViewportAtomicAdmission.test.mjs b/apps/control-station/test/rerunViewportAtomicAdmission.test.mjs
new file mode 100644
index 0000000..7464e78
--- /dev/null
+++ b/apps/control-station/test/rerunViewportAtomicAdmission.test.mjs
@@ -0,0 +1,154 @@
+import assert from "node:assert/strict";
+import { readFile } from "node:fs/promises";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let createRecordedOpenWatchdog;
+let recordedOpenWatchdogTimeoutMs;
+let rerunViewerInitialSource;
+let resolveRecordedViewerSourceUrl;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  ({
+    createRecordedOpenWatchdog,
+    recordedOpenWatchdogTimeoutMs,
+    rerunViewerInitialSource,
+    resolveRecordedViewerSourceUrl,
+  } = await server.ssrLoadModule("/src/components/RerunViewport.tsx"));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+const sourceUrl = "/api/v1/observation-sessions/session-atomic/recording.rrd";
+const sha256 = "a".repeat(64);
+const viewerSourceUrl = `${sourceUrl}?generation=${sha256}`;
+
+test("only the canonical digest-bound generation URL reaches the native Rerun receiver", () => {
+  const descriptor = {
+    sourceUrl,
+    viewerSourceUrl,
+    byteLength: 246_331_680,
+    sha256,
+  };
+  const resolved = resolveRecordedViewerSourceUrl(descriptor, "http://mission-core.test");
+  assert.equal(resolved, `http://mission-core.test${viewerSourceUrl}`);
+  assert.equal(rerunViewerInitialSource(resolved), resolved);
+
+  for (const unsafeViewerSourceUrl of [
+    sourceUrl,
+    `${sourceUrl}?generation=${"b".repeat(64)}`,
+    `${viewerSourceUrl}&extra=true`,
+    `https://foreign.test${viewerSourceUrl}`,
+  ]) {
+    assert.throws(
+      () => resolveRecordedViewerSourceUrl({
+        ...descriptor,
+        viewerSourceUrl: unsafeViewerSourceUrl,
+      }, "http://mission-core.test"),
+      /Unsafe recorded RRD viewer descriptor/,
+    );
+  }
+});
+
+test("recorded admission watchdog is size-aware and exits an incomplete load", () => {
+  const smallDelay = recordedOpenWatchdogTimeoutMs(4);
+  const currentDelay = recordedOpenWatchdogTimeoutMs(246_331_680);
+  const largeDelay = recordedOpenWatchdogTimeoutMs(805_687_122);
+  assert.ok(smallDelay >= 120_000);
+  assert.ok(currentDelay >= smallDelay);
+  assert.ok(largeDelay > currentDelay);
+  assert.ok(largeDelay <= 1_800_000);
+  assert.ok(largeDelay > 12_000);
+
+  let scheduledCallback;
+  let scheduledDelay;
+  let timeoutCount = 0;
+  const cancelled = [];
+  const watchdog = createRecordedOpenWatchdog({
+    byteLength: 246_331_680,
+    schedule(callback, timeoutMs) {
+      scheduledCallback = callback;
+      scheduledDelay = timeoutMs;
+      return 17;
+    },
+    cancel(handle) {
+      cancelled.push(handle);
+    },
+    onTimeout() {
+      timeoutCount += 1;
+    },
+  });
+  watchdog.arm();
+  assert.equal(watchdog.pending(), true);
+  assert.equal(scheduledDelay, currentDelay);
+  scheduledCallback();
+  assert.equal(timeoutCount, 1);
+  assert.equal(watchdog.pending(), false);
+  assert.deepEqual(cancelled, []);
+});
+
+test("complete recorded admission clears its watchdog", () => {
+  let timeoutCount = 0;
+  const cancelled = [];
+  const watchdog = createRecordedOpenWatchdog({
+    byteLength: 805_687_122,
+    schedule() {
+      return 23;
+    },
+    cancel(handle) {
+      cancelled.push(handle);
+    },
+    onTimeout() {
+      timeoutCount += 1;
+    },
+  });
+  watchdog.arm();
+  watchdog.clear();
+  assert.equal(watchdog.pending(), false);
+  assert.equal(timeoutCount, 0);
+  assert.deepEqual(cancelled, [23]);
+});
+
+test("recorded RRD bytes are never split across LogChannel.send_rrd calls", async () => {
+  const source = await readFile(
+    new URL("../src/components/RerunViewport.tsx", import.meta.url),
+    "utf8",
+  );
+  assert.doesNotMatch(source, /streamVerifiedRecordedRrd/);
+  assert.doesNotMatch(source, /missioncore\/recorded-recording/);
+  assert.doesNotMatch(source, /recordedChannel/);
+  assert.match(source, /viewer\.start\(\s*rerunViewerInitialSource\(resolvedSource\)/s);
+  assert.match(
+    source,
+    /recordingOpened = true;[\s\S]*if \(!isRecordedSource\) clearLiveRecordingOpenTimer\(\);/,
+  );
+  assert.match(
+    source,
+    /viewerStartResolved = true;\s*if \(isRecordedSource && !recordedSceneAdmitted\) recordedOpenWatchdog\?\.arm\(\);/,
+  );
+  assert.match(
+    source,
+    /if \(readyToRender && !readyPublished\)[\s\S]*clearRecordedAdmissionWatchdog\(\);/,
+  );
+});
+
+test("the complete vendor canvas host is hidden during partial and failed admission", async () => {
+  const css = await readFile(new URL("../src/styles/spatial.css", import.meta.url), "utf8");
+  assert.match(
+    css,
+    /\.rerun-viewport:is\(\[data-status="loading"\], \[data-status="error"\]\)\s+\.rerun-viewport__canvas\s*\{[^}]*visibility:\s*hidden;[^}]*pointer-events:\s*none;/s,
+  );
+  assert.doesNotMatch(
+    css,
+    /data-status="loading"[^}]*\.rerun-viewport__canvas\s*>\s*div/s,
+  );
+});
diff --git a/apps/control-station/test/rerunViewportPlayback.test.mjs b/apps/control-station/test/rerunViewportPlayback.test.mjs
new file mode 100644
index 0000000..8a3858f
--- /dev/null
+++ b/apps/control-station/test/rerunViewportPlayback.test.mjs
@@ -0,0 +1,96 @@
+import assert from "node:assert/strict";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let attemptRecordedAutoplay;
+let createLatestAnimationFrameEmitter;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  ({ attemptRecordedAutoplay, createLatestAnimationFrameEmitter } =
+    await server.ssrLoadModule("/src/components/RerunViewport.tsx"));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+test("recorded autoplay reports success only after seek and play both succeed", () => {
+  let seekAttempts = 0;
+  let playAttempts = 0;
+  const seekToStart = () => {
+    seekAttempts += 1;
+  };
+  const startPlaying = () => {
+    playAttempts += 1;
+    if (playAttempts === 1) throw new Error("receiver is not ready yet");
+  };
+
+  assert.equal(attemptRecordedAutoplay(seekToStart, startPlaying), false);
+  assert.equal(attemptRecordedAutoplay(seekToStart, startPlaying), true);
+  assert.equal(seekAttempts, 2);
+  assert.equal(playAttempts, 2);
+});
+
+test("recorded autoplay does not try play when the seek itself fails", () => {
+  let playAttempts = 0;
+
+  assert.equal(attemptRecordedAutoplay(
+    () => {
+      throw new Error("timeline is not ready yet");
+    },
+    () => {
+      playAttempts += 1;
+    },
+  ), false);
+  assert.equal(playAttempts, 0);
+});
+
+test("time updates coalesce to the latest value once per animation frame", () => {
+  let nextHandle = 1;
+  const frames = new Map();
+  const cancelled = [];
+  const emitted = [];
+  const emitter = createLatestAnimationFrameEmitter({
+    emit(value) {
+      emitted.push(value);
+    },
+    requestFrame(callback) {
+      const handle = nextHandle;
+      nextHandle += 1;
+      frames.set(handle, callback);
+      return handle;
+    },
+    cancelFrame(handle) {
+      cancelled.push(handle);
+      frames.delete(handle);
+    },
+  });
+
+  emitter.push(1);
+  emitter.push(2);
+  emitter.push(3);
+  assert.equal(frames.size, 1);
+  assert.deepEqual(emitted, []);
+
+  const firstFrame = frames.get(1);
+  frames.delete(1);
+  firstFrame(0);
+  assert.deepEqual(emitted, [3]);
+
+  emitter.push(4);
+  assert.equal(frames.size, 1);
+  emitter.cancel();
+  assert.deepEqual(cancelled, [2]);
+  assert.deepEqual(emitted, [3]);
+
+  emitter.push(5);
+  assert.equal(frames.size, 0);
+  assert.deepEqual(emitted, [3]);
+});
diff --git a/apps/control-station/test/rerunViewportProgressivePlayback.test.mjs b/apps/control-station/test/rerunViewportProgressivePlayback.test.mjs
new file mode 100644
index 0000000..78feef2
--- /dev/null
+++ b/apps/control-station/test/rerunViewportProgressivePlayback.test.mjs
@@ -0,0 +1,170 @@
+import assert from "node:assert/strict";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let canPublishRecordedPlaybackController;
+let createRecordedAutoplayGate;
+let isRecordedPlaybackReady;
+let isRecordedPlaybackPresentationReady;
+let isUsableRecordedPlaybackRange;
+let recordedPlaybackBufferState;
+let recordedPlaybackRangeWhenReady;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  ({
+    canPublishRecordedPlaybackController,
+    createRecordedAutoplayGate,
+    isRecordedPlaybackReady,
+    isRecordedPlaybackPresentationReady,
+    isUsableRecordedPlaybackRange,
+    recordedPlaybackBufferState,
+    recordedPlaybackRangeWhenReady,
+  } = await server.ssrLoadModule("/src/components/RerunViewport.tsx"));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+test("a first frame reports buffer telemetry but is not ready for presentation", () => {
+  assert.equal(isUsableRecordedPlaybackRange(null), false);
+  assert.equal(isUsableRecordedPlaybackRange({ min: Number.NaN, max: 0 }), false);
+  assert.equal(isUsableRecordedPlaybackRange({ min: 2, max: 1 }), false);
+  assert.equal(isUsableRecordedPlaybackRange({ min: 0, max: 0 }), true);
+
+  const firstFrame = recordedPlaybackBufferState({ min: 0, max: 0 }, 20);
+  assert.deepEqual(firstFrame, {
+    bufferedEndNs: 0,
+    expectedEndNs: 20_000_000_000,
+    bufferProgress: 0,
+    fullyBuffered: false,
+  });
+  assert.equal(isRecordedPlaybackReady(true, true, firstFrame), false);
+  assert.equal(recordedPlaybackRangeWhenReady({ min: 0, max: 0 }, firstFrame, true), null);
+});
+
+test("host timeline remains unmounted until the verified recording is fully ready", () => {
+  const partial = {
+    recordingId: "partial",
+    timeline: "session_time",
+    rangeNs: null,
+    currentNs: 0,
+    playing: false,
+    bufferedEndNs: 5,
+    expectedEndNs: 10,
+    bufferProgress: 0.5,
+    fullyBuffered: false,
+  };
+  assert.equal(isRecordedPlaybackPresentationReady("loading", partial), false);
+  assert.equal(isRecordedPlaybackPresentationReady("ready", partial), false);
+  assert.equal(isRecordedPlaybackPresentationReady("error", partial), false);
+  assert.equal(isRecordedPlaybackPresentationReady("ready", {
+    ...partial,
+    rangeNs: { min: 0, max: 10 },
+    bufferedEndNs: 10,
+    bufferProgress: 1,
+    fullyBuffered: true,
+  }), true);
+});
+
+test("buffer progress grows independently and preserves the full-buffer tolerance", () => {
+  assert.deepEqual(recordedPlaybackBufferState({ min: 0, max: 5_000_000_000 }, 20), {
+    bufferedEndNs: 5_000_000_000,
+    expectedEndNs: 20_000_000_000,
+    bufferProgress: 0.25,
+    fullyBuffered: false,
+  });
+
+  const complete = recordedPlaybackBufferState({ min: 0, max: 19_999_500_000 }, 20);
+  assert.equal(complete.bufferProgress, 0.999975);
+  assert.equal(complete.fullyBuffered, true);
+  assert.equal(isRecordedPlaybackReady(false, true, complete), false);
+  assert.equal(isRecordedPlaybackReady(true, false, complete), false);
+  assert.equal(isRecordedPlaybackReady(true, true, complete), true);
+  assert.equal(
+    recordedPlaybackRangeWhenReady({ min: 0, max: 19_999_500_000 }, complete, false),
+    null,
+  );
+  assert.deepEqual(
+    recordedPlaybackRangeWhenReady({ min: 0, max: 19_999_500_000 }, complete, true),
+    { min: 0, max: 19_999_500_000 },
+  );
+
+  const wrongDeclaredStart = recordedPlaybackBufferState(
+    { min: 5_000_000_000, max: 20_000_000_000 },
+    20,
+    0,
+  );
+  assert.equal(wrongDeclaredStart.bufferProgress, 1);
+  assert.equal(wrongDeclaredStart.fullyBuffered, false);
+  assert.equal(isRecordedPlaybackReady(true, true, wrongDeclaredStart), false);
+});
+
+test("recorded autoplay waits for the full range and then runs exactly once", () => {
+  const gate = createRecordedAutoplayGate();
+  const seeks = [];
+  let plays = 0;
+  const seek = (value) => seeks.push(value);
+  const play = () => {
+    plays += 1;
+  };
+
+  assert.equal(gate.attempt(false, true, true, { min: 0, max: 0 }, seek, play), false);
+  assert.equal(gate.attempt(true, false, true, { min: 0, max: 500_000_000 }, seek, play), false);
+  assert.equal(gate.attempt(true, true, false, { min: 0, max: 20_000_000_000 }, seek, play), false);
+  assert.deepEqual(seeks, []);
+  assert.equal(plays, 0);
+  assert.equal(gate.attempt(true, true, true, { min: 0, max: 20_000_000_000 }, seek, play), true);
+  assert.equal(gate.attempt(true, true, true, { min: 0, max: 20_000_000_000 }, seek, play), false);
+  assert.deepEqual(seeks, [0]);
+  assert.equal(plays, 1);
+  assert.equal(gate.attempted(), true);
+});
+
+test("a failed vendor autoplay attempt is consumed instead of rewinding later", () => {
+  const gate = createRecordedAutoplayGate();
+  let seeks = 0;
+  let plays = 0;
+
+  assert.equal(gate.attempt(
+    true,
+    true,
+    true,
+    { min: 0, max: 1 },
+    () => {
+      seeks += 1;
+    },
+    () => {
+      plays += 1;
+      throw new Error("receiver raced its first frame");
+    },
+  ), false);
+  assert.equal(gate.attempt(
+    true,
+    true,
+    true,
+    { min: 0, max: 2 },
+    () => {
+      seeks += 1;
+    },
+    () => {
+      plays += 1;
+    },
+  ), false);
+  assert.equal(seeks, 1);
+  assert.equal(plays, 1);
+});
+
+test("recorded playback controller stays unpublished until the aggregate gate is ready", () => {
+  assert.equal(canPublishRecordedPlaybackController(false, "ready"), false);
+  assert.equal(canPublishRecordedPlaybackController(true, "loading"), false);
+  assert.equal(canPublishRecordedPlaybackController(true, "error"), false);
+  assert.equal(canPublishRecordedPlaybackController(true, "ready"), true);
+});
diff --git a/apps/control-station/test/viewerSettingsCommit.test.mjs b/apps/control-station/test/viewerSettingsCommit.test.mjs
new file mode 100644
index 0000000..0972c61
--- /dev/null
+++ b/apps/control-station/test/viewerSettingsCommit.test.mjs
@@ -0,0 +1,178 @@
+import assert from "node:assert/strict";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let createLatestAsyncCommitter;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  ({ createLatestAsyncCommitter } = await server.ssrLoadModule(
+    "/src/core/runtime/latestAsyncCommitter.ts",
+  ));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+async function eventually(predicate, timeoutMs = 1_000) {
+  const deadline = Date.now() + timeoutMs;
+  while (!predicate()) {
+    if (Date.now() >= deadline) throw new Error("Timed out waiting for async commit queue");
+    await new Promise((resolve) => setTimeout(resolve, 0));
+  }
+}
+
+test("viewer settings commits are serialized and intermediate slider values collapse", async () => {
+  const calls = [];
+  const resolvers = [];
+  const settled = [];
+  const committer = createLatestAsyncCommitter({
+    commit(value) {
+      calls.push(value);
+      return new Promise((resolve) => resolvers.push(resolve));
+    },
+    onSettled(result) {
+      settled.push(result);
+    },
+  });
+
+  committer.enqueue({ accumulationSeconds: 1 });
+  committer.enqueue({ accumulationSeconds: 2 });
+  committer.enqueue({ accumulationSeconds: 12 });
+
+  assert.deepEqual(calls, [{ accumulationSeconds: 1 }]);
+  assert.equal(committer.isBusy(), true);
+  resolvers.shift()(true);
+  await eventually(() => calls.length === 2);
+
+  assert.deepEqual(calls[1], { accumulationSeconds: 12 });
+  assert.equal(settled[0].superseded, true);
+  resolvers.shift()(true);
+  await eventually(() => !committer.isBusy());
+
+  assert.deepEqual(settled.map(({ value, applied, superseded }) => ({
+    value,
+    applied,
+    superseded,
+  })), [
+    { value: { accumulationSeconds: 1 }, applied: true, superseded: true },
+    { value: { accumulationSeconds: 12 }, applied: true, superseded: false },
+  ]);
+});
+
+test("viewer settings commit failures settle as rejected without wedging the queue", async () => {
+  const settled = [];
+  const committer = createLatestAsyncCommitter({
+    async commit(value) {
+      if (value === "broken") throw new Error("offline");
+      return true;
+    },
+    onSettled(result) {
+      settled.push(result);
+    },
+  });
+
+  committer.enqueue("broken");
+  await eventually(() => settled.length === 1);
+  committer.enqueue("healthy");
+  await eventually(() => settled.length === 2);
+
+  assert.deepEqual(settled.map(({ value, applied }) => ({ value, applied })), [
+    { value: "broken", applied: false },
+    { value: "healthy", applied: true },
+  ]);
+  assert.equal(committer.isBusy(), false);
+});
+
+test("waitForIdle resolves only after the running commit and latest queued value settle", async () => {
+  const calls = [];
+  const resolvers = [];
+  const committer = createLatestAsyncCommitter({
+    commit(value) {
+      calls.push(value);
+      return new Promise((resolve) => resolvers.push(resolve));
+    },
+  });
+
+  committer.enqueue("initial");
+  committer.enqueue("latest");
+  let idle = false;
+  const idlePromise = committer.waitForIdle().then(() => {
+    idle = true;
+  });
+
+  await Promise.resolve();
+  assert.equal(idle, false);
+  resolvers.shift()(true);
+  await eventually(() => calls.length === 2);
+  assert.deepEqual(calls, ["initial", "latest"]);
+  assert.equal(idle, false);
+
+  resolvers.shift()(true);
+  await idlePromise;
+  assert.equal(idle, true);
+  assert.equal(committer.isBusy(), false);
+});
+
+test("waitForIdle observes work enqueued by onSettled and resolves immediately when idle", async () => {
+  const calls = [];
+  let committer;
+  committer = createLatestAsyncCommitter({
+    async commit(value) {
+      calls.push(value);
+      return true;
+    },
+    onSettled({ value }) {
+      if (value === "first") committer.enqueue("follow-up");
+    },
+  });
+
+  await committer.waitForIdle();
+  committer.enqueue("first");
+  await committer.waitForIdle();
+
+  assert.deepEqual(calls, ["first", "follow-up"]);
+  assert.equal(committer.isBusy(), false);
+});
+
+test("layout serialization can flush a staged setting and read the confirmed latest value", async () => {
+  let staged = { pointSize: 2 };
+  let confirmed = { pointSize: 1 };
+  let resolveCommit;
+  const committer = createLatestAsyncCommitter({
+    commit() {
+      return new Promise((resolve) => {
+        resolveCommit = resolve;
+      });
+    },
+    onSettled({ value, applied }) {
+      if (applied) confirmed = value;
+    },
+  });
+
+  const saveLayout = async () => {
+    committer.enqueue(staged);
+    await committer.waitForIdle();
+    return { sceneSettings: confirmed };
+  };
+
+  const savePromise = saveLayout();
+  staged = { pointSize: 9 };
+  let saved = false;
+  void savePromise.then(() => {
+    saved = true;
+  });
+  await Promise.resolve();
+  assert.equal(saved, false);
+
+  resolveCommit(true);
+  const layout = await savePromise;
+  assert.deepEqual(layout, { sceneSettings: { pointSize: 2 } });
+});
diff --git a/apps/control-station/test/workspaceLayout.test.mjs b/apps/control-station/test/workspaceLayout.test.mjs
new file mode 100644
index 0000000..248c944
--- /dev/null
+++ b/apps/control-station/test/workspaceLayout.test.mjs
@@ -0,0 +1,229 @@
+import assert from "node:assert/strict";
+import { after, before, test } from "node:test";
+
+import { createServer } from "vite";
+
+let server;
+let decodeObservationWorkspaceLayoutProfile;
+let encodeObservationWorkspaceLayoutProfile;
+let fetchObservationWorkspaceLayoutProfile;
+let normalizeObservationWindowRect;
+let projectObservationLayoutSnapshot;
+let saveObservationWorkspaceLayoutProfile;
+let WorkspaceLayoutApiError;
+let WorkspaceLayoutContractError;
+let observationPresentationSourceAfterLayoutApply;
+
+before(async () => {
+  server = await createServer({
+    appType: "custom",
+    logLevel: "silent",
+    server: { middlewareMode: true },
+  });
+  ({
+    decodeObservationWorkspaceLayoutProfile,
+    encodeObservationWorkspaceLayoutProfile,
+    fetchObservationWorkspaceLayoutProfile,
+    normalizeObservationWindowRect,
+    projectObservationLayoutSnapshot,
+    saveObservationWorkspaceLayoutProfile,
+    WorkspaceLayoutApiError,
+    WorkspaceLayoutContractError,
+  } = await server.ssrLoadModule("/src/core/observation/workspaceLayout.ts"));
+  ({ observationPresentationSourceAfterLayoutApply } = await server.ssrLoadModule(
+    "/src/core/observation/useObservationLayout.ts",
+  ));
+});
+
+after(async () => {
+  await server?.close();
+});
+
+function wireProfile(overrides = {}) {
+  return {
+    version: 1,
+    revision: 7,
+    workspace_id: "observation.spatial",
+    scene_settings: {
+      projection: "3d",
+      point_size: 2.5,
+      color_mode: "intensity",
+      palette: "turbo",
+      custom_color: "#35d7c1",
+      accumulation_seconds: 12,
+      show_points: true,
+      show_trajectory: true,
+      show_grid: true,
+      show_labels: false,
+      show_camera_frustums: true,
+    },
+    tool_windows: {
+      sources_open: true,
+      display_open: false,
+      layers_open: true,
+      order: ["sources", "layers", "display"],
+    },
+    visible_source_ids: ["spatial.point-cloud.live", "camera.left"],
+    active_floating_source_id: "camera.left",
+    window_rects: {
+      "camera.left": { x: 0.1, y: 0.1, width: 0.4, height: 0.4 },
+      "camera.right": { x: 0.55, y: 0.1, width: 0.4, height: 0.4 },
+    },
+    viewport_size: { width: 1_000, height: 500 },
+    ...overrides,
+  };
+}
+
+test("workspace layout performs a lossless strict wire/camel/wire round trip", () => {
+  const wire = wireProfile();
+  const profile = decodeObservationWorkspaceLayoutProfile(wire);
+
+  assert.deepEqual(profile.visibleSourceIds, ["spatial.point-cloud.live", "camera.left"]);
+  assert.deepEqual(profile.toolWindows.order, ["sources", "layers", "display"]);
+  assert.equal(profile.sceneSettings.pointSize, 2.5);
+  assert.deepEqual(encodeObservationWorkspaceLayoutProfile(profile), wire);
+});
+
+test("workspace layout rejects unknown fields, transient transport data and invalid schema values", () => {
+  assert.throws(
+    () => decodeObservationWorkspaceLayoutProfile({
+      ...wireProfile(),
+      source_url: "ws://192.168.68.52:9877",
+    }),
+    WorkspaceLayoutContractError,
+  );
+  assert.throws(
+    () => decodeObservationWorkspaceLayoutProfile(wireProfile({ version: 2 })),
+    /Неподдерживаемая версия/,
+  );
+  assert.throws(
+    () => decodeObservationWorkspaceLayoutProfile(wireProfile({ revision: 1.5 })),
+    /revision/,
+  );
+  assert.throws(
+    () => decodeObservationWorkspaceLayoutProfile(wireProfile({
+      visible_source_ids: ["../camera"],
+      active_floating_source_id: null,
+    })),
+    /стабильный идентификатор/,
+  );
+  assert.throws(
+    () => decodeObservationWorkspaceLayoutProfile(wireProfile({
+      window_rects: { "camera.left": { x: 0.8, y: 0, width: 0.4, height: 0.5 } },
+    })),
+    /выходит за нормализованные границы/,
+  );
+  assert.throws(
+    () => decodeObservationWorkspaceLayoutProfile(wireProfile({
+      tool_windows: {
+        sources_open: true,
+        display_open: true,
+        layers_open: true,
+        order: ["sources", "sources", "layers"],
+      },
+    })),
+    /перестановкой/,
+  );
+  assert.throws(
+    () => decodeObservationWorkspaceLayoutProfile(wireProfile({
+      scene_settings: { ...wireProfile().scene_settings, point_size: Number.POSITIVE_INFINITY },
+    })),
+    /point_size/,
+  );
+});
+
+test("restored desired layout survives an empty catalog and reveals only known stable sources later", () => {
+  const profile = decodeObservationWorkspaceLayoutProfile(wireProfile());
+  const snapshot = {
+    visibleSourceIds: profile.visibleSourceIds,
+    activeFloatingSourceId: profile.activeFloatingSourceId,
+    windowRects: profile.windowRects,
+    viewportSize: profile.viewportSize,
+  };
+
+  const empty = projectObservationLayoutSnapshot(snapshot, new Set(), { width: 500, height: 1_000 });
+  assert.deepEqual(empty, {
+    visibleSourceIds: [],
+    activeFloatingSourceId: null,
+    windowRects: {},
+  });
+  assert.deepEqual(snapshot.visibleSourceIds, ["spatial.point-cloud.live", "camera.left"]);
+
+  const cameraAppeared = projectObservationLayoutSnapshot(
+    snapshot,
+    new Set(["camera.left"]),
+    { width: 500, height: 1_000 },
+  );
+  assert.deepEqual(cameraAppeared.visibleSourceIds, ["camera.left"]);
+  assert.equal(cameraAppeared.activeFloatingSourceId, "camera.left");
+  assert.deepEqual(cameraAppeared.windowRects["camera.left"], {
+    x: 50,
+    y: 100,
+    width: 200,
+    height: 400,
+  });
+});
+
+test("window rectangles normalize once and project proportionally into a different viewport", () => {
+  assert.deepEqual(
+    normalizeObservationWindowRect(
+      { x: 100, y: 50, width: 400, height: 200 },
+      { width: 1_000, height: 500 },
+    ),
+    { x: 0.1, y: 0.1, width: 0.4, height: 0.4 },
+  );
+});
+
+test("fullscreen presentation survives the viewport resize it causes", () => {
+  assert.equal(
+    observationPresentationSourceAfterLayoutApply("camera.left", "preserve"),
+    "camera.left",
+  );
+  assert.equal(
+    observationPresentationSourceAfterLayoutApply("camera.left", "reset"),
+    null,
+  );
+});
+
+test("workspace layout API uses the canonical endpoint and optimistic revision", async () => {
+  const calls = [];
+  const current = decodeObservationWorkspaceLayoutProfile(wireProfile());
+  const saved = await saveObservationWorkspaceLayoutProfile(current, {
+    fetcher: async (input, init) => {
+      calls.push({ input: String(input), init, body: JSON.parse(String(init.body)) });
+      return new Response(JSON.stringify(wireProfile({ revision: 8 })), {
+        status: 200,
+        headers: { "Content-Type": "application/json" },
+      });
+    },
+  });
+
+  assert.equal(calls.length, 1);
+  assert.equal(calls[0].input, "/api/v1/workspace-layouts/observation.spatial");
+  assert.equal(calls[0].init.method, "PUT");
+  assert.equal(calls[0].init.headers["If-Match"], '"7"');
+  assert.equal(calls[0].body.revision, 7);
+  assert.equal(calls[0].body.workspace_id, "observation.spatial");
+  assert.equal(saved.revision, 8);
+});
+
+test("workspace layout API treats 404 as no profile and exposes revision conflicts", async () => {
+  assert.equal(
+    await fetchObservationWorkspaceLayoutProfile({
+      fetcher: async () => new Response(null, { status: 404 }),
+    }),
+    null,
+  );
+
+  const current = decodeObservationWorkspaceLayoutProfile(wireProfile());
+  await assert.rejects(
+    saveObservationWorkspaceLayoutProfile(current, {
+      fetcher: async () => new Response(JSON.stringify({ detail: "revision mismatch" }), {
+        status: 412,
+        headers: { "Content-Type": "application/json" },
+      }),
+    }),
+    (error) => error instanceof WorkspaceLayoutApiError &&
+      error.conflict && error.status === 412 && error.message === "revision mismatch",
+  );
+});