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/stores/useSessionFoldersStore.test.ts

@@ -2,6 +2,8 @@ import { beforeEach, describe, expect, mock, test } from 'bun:test';
 
 const storage = new Map<string, string>();
 let storageSetCount = 0;
+let runtimeKey = 'runtime-a';
+let diskResponseBody: Record<string, unknown> = { version: 1, exists: false };
 
 const safeStorage = {
   getItem: (key: string) => storage.get(key) ?? null,
@@ -31,8 +33,9 @@ mock.module('@/lib/desktop', () => ({
 }));
 
 mock.module('@/lib/runtime-fetch', () => ({
-  runtimeFetch: mock(async () => new Response('{}', { headers: { 'Content-Type': 'application/json' } })),
+  runtimeFetch: mock(async () => new Response(JSON.stringify(diskResponseBody), { headers: { 'Content-Type': 'application/json' } })),
 }));
+mock.module('@/lib/runtime-switch', () => ({ getRuntimeKey: () => runtimeKey }));
 
 const { useSessionFoldersStore } = await import('./useSessionFoldersStore');
 
@@ -42,6 +45,9 @@ describe('useSessionFoldersStore folder assignments', () => {
   beforeEach(() => {
     storage.clear();
     storageSetCount = 0;
+    runtimeKey = 'runtime-a';
+    diskResponseBody = { version: 1, exists: false };
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
     useSessionFoldersStore.setState({
       foldersMap: {},
       collapsedFolderIds: new Set<string>(),
@@ -77,4 +83,54 @@ describe('useSessionFoldersStore folder assignments', () => {
     expect(useSessionFoldersStore.getState().foldersMap).toBe(before);
     expect(storageSetCount).toBe(0);
   });
+
+  test('restores independent folder snapshots across runtime switches', async () => {
+    useSessionFoldersStore.getState().createFolder('/workspace/project', 'Runtime A');
+    await waitForPersist();
+
+    runtimeKey = 'runtime-b';
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+    expect(useSessionFoldersStore.getState().getFoldersForScope('/workspace/project')).toEqual([]);
+    useSessionFoldersStore.getState().createFolder('/workspace/project', 'Runtime B');
+    await waitForPersist();
+
+    runtimeKey = 'runtime-a';
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+    expect(useSessionFoldersStore.getState().getFoldersForScope('/workspace/project').map((folder) => folder.name)).toEqual(['Runtime A']);
+  });
+
+  test('flushes the outgoing runtime before a debounced browser write can be lost', () => {
+    useSessionFoldersStore.getState().createFolder('/workspace/project', 'Runtime A pending');
+
+    runtimeKey = 'runtime-b';
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+    runtimeKey = 'runtime-a';
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+
+    expect(useSessionFoldersStore.getState().getFoldersForScope('/workspace/project').map((folder) => folder.name)).toEqual(['Runtime A pending']);
+  });
+
+  test('does not replace browser folders when the server has no disk snapshot', async () => {
+    useSessionFoldersStore.getState().createFolder('/workspace/project', 'Browser folder');
+    runtimeKey = 'runtime-b';
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+    runtimeKey = 'runtime-a';
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
+    expect(useSessionFoldersStore.getState().getFoldersForScope('/workspace/project').map((folder) => folder.name)).toEqual(['Browser folder']);
+  });
+
+  test('does not silently evict folder state from older runtimes', () => {
+    for (let index = 0; index < 10; index += 1) {
+      runtimeKey = `runtime-${index}`;
+      useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+      useSessionFoldersStore.getState().createFolder('/workspace/project', `Folder ${index}`);
+    }
+
+    runtimeKey = 'runtime-0';
+    useSessionFoldersStore.getState().resetForRuntimeSwitch(runtimeKey);
+    expect(useSessionFoldersStore.getState().getFoldersForScope('/workspace/project').map((folder) => folder.name)).toEqual(['Folder 0']);
+  });
 });