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/live-aggregate.ts

@@ -1,6 +1,7 @@
 import type { SessionStatus } from '@opencode-ai/sdk/v2/client'
 import type { Session } from '@opencode-ai/sdk/v2'
 import type { State } from './types'
+import { countSyncPerformance } from './performance-diagnostics'
 
 type LiveStateSlice = Pick<State, 'session' | 'session_status'>
 
@@ -158,10 +159,16 @@ export function aggregateLiveSessionStatuses(states: Iterable<LiveStateSlice>):
   const candidates = new Map<string, StatusCandidate>()
 
   for (const state of states) {
-    for (const sessionId of Object.keys(state.session_status ?? {})) {
-      const next = getStatusCandidate(state, sessionId)
-      if (!next) {
-        continue
+    const sessionUpdatedAtById = new Map<string, number>()
+    for (const session of state.session) {
+      countSyncPerformance('statusAggregationSessionEntries')
+      sessionUpdatedAtById.set(session.id, getSessionUpdatedAt(session))
+    }
+    for (const [sessionId, status] of Object.entries(state.session_status ?? {})) {
+      countSyncPerformance('statusAggregationCandidates')
+      const next: StatusCandidate = {
+        status,
+        sessionUpdatedAt: sessionUpdatedAtById.get(sessionId) ?? -1,
       }
 
       const current = candidates.get(sessionId)