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/web/server/lib/opencode/env-runtime.test.js

@@ -163,7 +163,7 @@ describe('OpenCode env runtime', () => {
     expect(state.resolvedOpencodeBinarySource).toBe('settings');
   });
 
-  it('prefers a user-installed OpenCode from PATH over the bundled CLI', () => {
+  it('prefers the bundled CLI over a user-installed OpenCode from PATH', () => {
     const bundledDir = createTempDir('openchamber-bundled-opencode-');
     const bundledBinary = path.join(bundledDir, process.platform === 'win32' ? 'opencode.exe' : 'opencode');
     const pathDir = createTempDir('openchamber-path-opencode-');
@@ -179,8 +179,8 @@ describe('OpenCode env runtime', () => {
     delete process.env.OPENCODE_BINARY;
     const { runtime, state } = createRuntime({});
 
-    expect(runtime.resolveOpencodeCliPath()).toBe(pathBinary);
-    expect(state.resolvedOpencodeBinarySource).toBe('path');
+    expect(runtime.resolveOpencodeCliPath()).toBe(bundledBinary);
+    expect(state.resolvedOpencodeBinarySource).toBe('bundled');
   });
 
   it('keeps explicit OpenCode binary ahead of bundled CLI', () => {
@@ -202,7 +202,7 @@ describe('OpenCode env runtime', () => {
     expect(state.resolvedOpencodeBinarySource).toBe('env');
   });
 
-  it('falls back to the bundled OpenCode CLI from Electron resourcesPath when nothing else is installed', () => {
+  it('resolves the bundled OpenCode CLI from Electron resourcesPath', () => {
     const resourcesPath = createTempDir('openchamber-resources-');
     const bundledDir = path.join(resourcesPath, 'opencode-cli');
     const bundledBinary = path.join(bundledDir, process.platform === 'win32' ? 'opencode.exe' : 'opencode');
@@ -218,8 +218,6 @@ describe('OpenCode env runtime', () => {
     process.env.PATH = createTempDir('openchamber-empty-path-');
     delete process.env.OPENCHAMBER_BUNDLED_OPENCODE_CLI_DIR;
     delete process.env.OPENCODE_BINARY;
-    // The bundled CLI is the LAST resort now — hide the machine's own installs
-    // from the home-directory fallbacks and shell discovery.
     const emptyHome = createTempDir('openchamber-empty-home-');
     const { runtime, state } = createRuntime({}, {
       spawnSync: () => ({ status: 1, stdout: '', stderr: '' }),