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/apps/MobileChangesSurface.tsx

@@ -21,6 +21,7 @@ import {
   useIsGitRepo,
   useGitLoadingStatus,
 } from '@/stores/useGitStore';
+import { getRuntimeKey } from '@/lib/runtime-switch';
 
 type SyncAction = 'fetch' | 'pull' | 'push' | 'sync' | null;
 type CommitAction = 'commit' | 'commitAndPush' | null;
@@ -202,6 +203,7 @@ export const MobileChangesSurface: React.FC<MobileChangesSurfaceProps> = ({ onCl
     }
 
     let cancelled = false;
+    const runtimeKey = getRuntimeKey();
     setDiffLoadError(null);
     void git.getGitFileDiff(currentDirectory, { path: route.path, staged: route.staged || undefined })
       .then((response) => {
@@ -210,7 +212,7 @@ export const MobileChangesSurface: React.FC<MobileChangesSurfaceProps> = ({ onCl
           original: response.original ?? '',
           modified: response.modified ?? '',
           isBinary: response.isBinary,
-        });
+        }, runtimeKey);
       })
       .catch((error) => {
         if (cancelled) return;