wip(k1): checkpoint connection recovery rewrite

Capture the current unreleased K1 connection, recovery, lifecycle, viewer, and test work as a single known-bad baseline for subsequent fixes.

plugins/xgrids-k1/frontend/src/stateOrdering.ts

@@ -10,6 +10,66 @@ function deviceSessionScope(state: XgridsK1State): string | null {
   return typeof sessionId === "string" && sessionId.trim() ? sessionId : null;
 }
 
+interface RuntimeSnapshotStamp {
+  startedAtMonotonicNs: bigint | null;
+  startedAtEpochMs: number | null;
+  runtimeId: string;
+  revision: number;
+}
+
+function monotonicNanoseconds(value: string | null | undefined): bigint | null {
+  if (typeof value !== "string" || !/^(0|[1-9][0-9]*)$/.test(value)) return null;
+  try {
+    return BigInt(value);
+  } catch {
+    return null;
+  }
+}
+
+function runtimeSnapshotStamp(state: XgridsK1State): RuntimeSnapshotStamp | null {
+  const startedAt = state.snapshot_runtime_started_at_utc;
+  const startedAtMonotonicNs = monotonicNanoseconds(
+    state.snapshot_runtime_started_monotonic_ns,
+  );
+  const runtimeId = state.snapshot_runtime_id;
+  const revision = monotonicInteger(state.snapshot_revision);
+  if (
+    typeof runtimeId !== "string"
+    || !runtimeId.trim()
+    || revision === null
+  ) {
+    return null;
+  }
+  const parsedEpochMs = typeof startedAt === "string" ? Date.parse(startedAt) : Number.NaN;
+  const startedAtEpochMs = Number.isFinite(parsedEpochMs) ? parsedEpochMs : null;
+  if (startedAtMonotonicNs === null && startedAtEpochMs === null) return null;
+  return { startedAtMonotonicNs, startedAtEpochMs, runtimeId, revision };
+}
+
+function stampedSnapshotIsAtLeastAsNew(
+  current: RuntimeSnapshotStamp,
+  incoming: RuntimeSnapshotStamp,
+): boolean {
+  if (incoming.runtimeId === current.runtimeId) {
+    return incoming.revision >= current.revision;
+  }
+  if (incoming.startedAtMonotonicNs !== null || current.startedAtMonotonicNs !== null) {
+    if (incoming.startedAtMonotonicNs === null) return false;
+    if (current.startedAtMonotonicNs === null) return true;
+    return incoming.startedAtMonotonicNs > current.startedAtMonotonicNs;
+  }
+  if (
+    incoming.startedAtEpochMs !== null
+    && current.startedAtEpochMs !== null
+    && incoming.startedAtEpochMs !== current.startedAtEpochMs
+  ) {
+    return incoming.startedAtEpochMs > current.startedAtEpochMs;
+  }
+  // Legacy UTC-only process identities with equal timestamps cannot be
+  // ordered safely. Keep the already accepted authority.
+  return false;
+}
+
 function cameraSnapshotIsAtLeastAsNew(
   current: XgridsCameraPreviewState,
   incoming: XgridsCameraPreviewState,
@@ -43,6 +103,17 @@ export function selectMonotonicXgridsState(
   current: XgridsK1State | null,
   incoming: XgridsK1State,
 ): XgridsK1State {
+  if (!current) return incoming;
+  const currentStamp = runtimeSnapshotStamp(current);
+  const incomingStamp = runtimeSnapshotStamp(incoming);
+  if (currentStamp || incomingStamp) {
+    if (!currentStamp) return incoming;
+    if (!incomingStamp) return current;
+    return stampedSnapshotIsAtLeastAsNew(currentStamp, incomingStamp)
+      ? incoming
+      : current;
+  }
+
   if (current && deviceSessionScope(current) !== deviceSessionScope(incoming)) {
     return incoming;
   }