perf: overhaul session loading, caching, and runtime isolation (#2360)

Improve OpenChamber responsiveness under large session workloads while fixing
cache, synchronization, and persistence correctness across runtimes, projects,
directories, and worktrees.

- prioritize selected and visible sessions during bootstrap and defer
  non-critical enrichment work
- reduce redundant message loading, event processing, store publication, and
  hidden sidebar work
- prevent stale session and message requests from overwriting newer
  authoritative state
- preserve existing data when authoritative fetches fail instead of treating
  failures as successful empty responses
- scope session materialization, messages, drafts, queues, todos, pins,
  permissions, folders, tabs, Git state, and pull request data by runtime and
  directory identity
- harden runtime switching, reconnect, cleanup, mutation reconciliation, and
  persisted-state ordering
- preserve live subagent Task linkage when metadata arrives after an older
  message request or while streaming parts are suspended
- coalesce overlapping tail refreshes without losing newer refresh demand
- improve cold-session loading by moving deferrable work out of the critical
  bootstrap path
- isolate URL authentication, mobile credentials, native secrets, and other
  runtime-owned state across endpoint changes
- bound long-lived caches and remove avoidable allocations from event and
  rendering hot paths
- limit virtualization to archive collections where it improves rendering
  without disrupting active sidebar layout
- stabilize session folders, pin ordering, expanded state, and persisted
  sidebar behavior
- open skill files through the same secure editor and outside-workspace grant
  flow used by file navigation, including worktree sessions
- expand regression coverage for stale completions, runtime collisions,
  reconnect behavior, persistence races, authoritative empty results, and
  subagent refresh ordering
- document the updated synchronization, cache ownership, performance, and
  runtime-isolation invariants

packages/ui/src/sync/performance-diagnostics.ts

@@ -0,0 +1,126 @@
+const STORAGE_KEY = "openchamber_sync_perf"
+
+declare global {
+  interface Window {
+    __openchamberSyncPerformance?: {
+      getSnapshot: () => SyncPerformanceCounters | null
+      reset: () => void
+    }
+  }
+}
+
+export type SyncPerformanceCounters = {
+  pipelineRawEvents: number
+  pipelineCoalescedEvents: number
+  pipelineDeliveredEvents: number
+  reducerEvents: number
+  reducerChangedEvents: number
+  directoryStorePublications: number
+  streamingFullReconciliations: number
+  streamingIncrementalReconciliations: number
+  streamingStatusEntriesVisited: number
+  streamingSessionCandidatesVisited: number
+  streamingMessagesVisited: number
+  streamingHeartbeatAttempts: number
+  streamingHeartbeatCommits: number
+  permissionChangeCallbacks: number
+  sessionMessageChangeCallbacks: number
+  sessionRenderableNotificationSkips: number
+  userMessageHistoryNotificationSkips: number
+  sessionMessageRecordNotificationSkips: number
+  materializationEnqueues: number
+  materializationEmptyAssistantEnqueues: number
+  materializationMissingMessageEnqueues: number
+  materializationMissingPartEnqueues: number
+  materializationLifecycleEnqueues: number
+  materializationPreflightSkips: number
+  materializationRequests: number
+  statusAggregationSessionEntries: number
+  statusAggregationCandidates: number
+  persistenceSerializations: number
+  persistenceStorageWrites: number
+  persistenceUtf8Bytes: number
+}
+
+const createCounters = (): SyncPerformanceCounters => ({
+  pipelineRawEvents: 0,
+  pipelineCoalescedEvents: 0,
+  pipelineDeliveredEvents: 0,
+  reducerEvents: 0,
+  reducerChangedEvents: 0,
+  directoryStorePublications: 0,
+  streamingFullReconciliations: 0,
+  streamingIncrementalReconciliations: 0,
+  streamingStatusEntriesVisited: 0,
+  streamingSessionCandidatesVisited: 0,
+  streamingMessagesVisited: 0,
+  streamingHeartbeatAttempts: 0,
+  streamingHeartbeatCommits: 0,
+  permissionChangeCallbacks: 0,
+  sessionMessageChangeCallbacks: 0,
+  sessionRenderableNotificationSkips: 0,
+  userMessageHistoryNotificationSkips: 0,
+  sessionMessageRecordNotificationSkips: 0,
+  materializationEnqueues: 0,
+  materializationEmptyAssistantEnqueues: 0,
+  materializationMissingMessageEnqueues: 0,
+  materializationMissingPartEnqueues: 0,
+  materializationLifecycleEnqueues: 0,
+  materializationPreflightSkips: 0,
+  materializationRequests: 0,
+  statusAggregationSessionEntries: 0,
+  statusAggregationCandidates: 0,
+  persistenceSerializations: 0,
+  persistenceStorageWrites: 0,
+  persistenceUtf8Bytes: 0,
+})
+
+const readInitialEnabled = (): boolean => {
+  if (typeof window === "undefined") return false
+  try {
+    return window.localStorage.getItem(STORAGE_KEY) === "1"
+  } catch {
+    return false
+  }
+}
+
+let activeCounters: SyncPerformanceCounters | null = readInitialEnabled() ? createCounters() : null
+
+export function setSyncPerformanceDiagnosticsEnabled(enabled: boolean): void {
+  activeCounters = enabled ? createCounters() : null
+}
+
+export function resetSyncPerformanceDiagnostics(): void {
+  if (activeCounters) activeCounters = createCounters()
+}
+
+export function getSyncPerformanceDiagnostics(): SyncPerformanceCounters | null {
+  return activeCounters ? { ...activeCounters } : null
+}
+
+export function countSyncPerformance(
+  counter: keyof SyncPerformanceCounters,
+  amount = 1,
+): void {
+  const counters = activeCounters
+  if (!counters) return
+  counters[counter] += amount
+}
+
+export function countSyncPersistenceSerialization(serialized: string): void {
+  const counters = activeCounters
+  if (!counters) return
+  counters.persistenceSerializations += 1
+  counters.persistenceUtf8Bytes += new TextEncoder().encode(serialized).byteLength
+}
+
+export function countSyncPersistenceStorageWrite(): void {
+  if (activeCounters) activeCounters.persistenceStorageWrites += 1
+}
+
+if (typeof window !== "undefined") {
+  window.__openchamberSyncPerformance = {
+    getSnapshot: getSyncPerformanceDiagnostics,
+    reset: resetSyncPerformanceDiagnostics,
+  }
+}