fix(k1): keep live viewer on stream edge

apps/control-station/src/components/RerunViewport.tsx

@@ -551,6 +551,12 @@ export function rerunViewerInitialSource(
   return resolvedSourceUrl;
 }
 
+export function rerunViewerOpenOptions(
+  followLive: boolean,
+): { follow_if_http: true } | null {
+  return followLive ? { follow_if_http: true } : null;
+}
+
 export function resolveRecordedBlueprintUrl(sourceUrl: string, origin: string): string | null {
   const normalized = sourceUrl.trim();
   if (!RECORDED_RRD_PATH.test(normalized)) return null;
@@ -1631,7 +1637,7 @@ export function RerunViewport({
             rerunViewerInitialSource(resolvedSource),
             host,
             viewerOptions,
-            null,
+            rerunViewerOpenOptions(followLive),
           );
           if (disposed) {
             disposeViewer();

apps/control-station/test/rerunViewportAtomicAdmission.test.mjs

@@ -10,6 +10,7 @@ let createRecordedOpenWatchdog;
 let createReentrantViewerDisposer;
 let recordedOpenWatchdogTimeoutMs;
 let rerunViewerInitialSource;
+let rerunViewerOpenOptions;
 let resolveRecordedViewerSourceUrl;
 
 before(async () => {
@@ -24,6 +25,7 @@ before(async () => {
     createReentrantViewerDisposer,
     recordedOpenWatchdogTimeoutMs,
     rerunViewerInitialSource,
+    rerunViewerOpenOptions,
     resolveRecordedViewerSourceUrl,
   } = await server.ssrLoadModule("/src/components/RerunViewport.tsx"));
 });
@@ -63,6 +65,11 @@ test("only the canonical digest-bound generation URL reaches the native Rerun re
   }
 });
 
+test("only the live receiver opens on the native following edge", () => {
+  assert.deepEqual(rerunViewerOpenOptions(true), { follow_if_http: true });
+  assert.equal(rerunViewerOpenOptions(false), null);
+});
+
 test("recorded admission watchdog is size-aware and exits an incomplete load", () => {
   const smallDelay = recordedOpenWatchdogTimeoutMs(4);
   const currentDelay = recordedOpenWatchdogTimeoutMs(246_331_680);
@@ -170,6 +177,7 @@ test("recorded RRD bytes are never split across LogChannel.send_rrd calls", asyn
   assert.doesNotMatch(source, /missioncore\/recorded-recording/);
   assert.doesNotMatch(source, /recordedChannel/);
   assert.match(source, /viewer\.start\(\s*rerunViewerInitialSource\(resolvedSource\)/s);
+  assert.match(source, /rerunViewerOpenOptions\(followLive\)/);
   assert.match(
     source,
     /recordingOpened = true;[\s\S]*diagnosticLifecycle\.markAdmitted\(\);/,