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/globalSessions.test.ts

@@ -95,4 +95,29 @@ describe('listGlobalSessionPages', () => {
     expect(calls[1]).toEqual({ directory: '/repo', archived: false, roots: false, limit: 2, cursor: 10 })
     expect(sessions.map((session) => session.id)).toEqual(['ses_root', 'ses_child_1', 'ses_child_2'])
   })
+
+  test('retries SDK error responses before treating the load as failed', async () => {
+    let calls = 0
+    const apiClient = {
+      experimental: {
+        session: {
+          list: async () => {
+            calls += 1
+            if (calls === 1) {
+              return { error: { message: 'warming up' }, response: { status: 503 } }
+            }
+            return {
+              data: [{ id: 'ses_1', time: { updated: 1 } }],
+              response: { headers: new Headers() },
+            }
+          },
+        },
+      },
+    } as unknown as OpencodeClient
+
+    const sessions = await listGlobalSessionPages(apiClient, { archived: false, pageSize: 500 })
+
+    expect(calls).toBe(2)
+    expect(sessions.map((session) => session.id)).toEqual(['ses_1'])
+  })
 })