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/session-message-records.test.ts

@@ -18,6 +18,16 @@ const textPart = (id: string, text: string): Part => ({
   text,
 } as Part);
 
+const taskPart = (id: string, sessionId?: string): Part => ({
+  id,
+  type: 'tool',
+  tool: 'task',
+  state: {
+    status: 'running',
+    metadata: sessionId ? { sessionId } : {},
+  },
+} as unknown as Part);
+
 const state = (partial: Partial<State>): State => ({
   ...INITIAL_STATE,
   ...partial,
@@ -65,4 +75,27 @@ describe('buildSessionMessageRecordsSnapshot', () => {
     expect(next.byId.get('assistant_1')?.parts).toBe(assistant1FinalParts);
     expect(next.byId.get('assistant_2')?.parts).toBe(assistant2InitialParts);
   });
+
+  test('publishes task session identity while other streaming part updates are suspended', () => {
+    const assistant = message('assistant_1', 'assistant');
+    const initialParts = [taskPart('task_1')];
+    const previous = buildSessionMessageRecordsSnapshot(
+      state({ message: { ses_1: [assistant] }, part: { assistant_1: initialParts } }),
+      'ses_1',
+      undefined,
+      true,
+      assistant.id,
+    );
+    const identifiedParts = [taskPart('task_1', 'child_1')];
+
+    const next = buildSessionMessageRecordsSnapshot(
+      state({ message: { ses_1: [assistant] }, part: { assistant_1: identifiedParts } }),
+      'ses_1',
+      previous,
+      true,
+      assistant.id,
+    );
+
+    expect(next.byId.get(assistant.id)?.parts).toBe(identifiedParts);
+  });
 });