v2.2-paseo-providers: Paseo provider stack + v2.2.1 pane-scoped chat fixes

Ship Paseo-equivalent provider snapshot, AgentComposerBar, ACP dispatch
rewrite with streaming/persist, permission prompts, and agent commands.
Follow-up: pane-scoped chat resolution, CoderMessageList tool timeline,
WS user-delta replace, and inference orphan tool_call stripping.
Archive openspec v2-2; update CHANGELOG and CURRENT.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/web/src/hooks/useProviderSnapshot.ts

@@ -0,0 +1,49 @@
+import { useEffect, useSyncExternalStore } from 'react';
+import { api } from '@/api/client';
+import type { ProviderSnapshotEntry } from '@/api/types';
+
+let cached: ProviderSnapshotEntry[] | null = null;
+let inflight: Promise<ProviderSnapshotEntry[]> | null = null;
+const listeners = new Set<() => void>();
+
+function notify(): void {
+  for (const fn of listeners) fn();
+}
+
+function subscribe(fn: () => void): () => void {
+  listeners.add(fn);
+  return () => listeners.delete(fn);
+}
+
+function getSnapshot(): ProviderSnapshotEntry[] | null {
+  return cached;
+}
+
+async function doFetch(cwd?: string): Promise<ProviderSnapshotEntry[]> {
+  const data = await api.coder.snapshot(cwd);
+  cached = data;
+  inflight = null;
+  notify();
+  return data;
+}
+
+function ensureLoaded(cwd?: string): void {
+  if (cached || inflight) return;
+  inflight = doFetch(cwd).catch((err) => {
+    inflight = null;
+    console.error('provider snapshot fetch failed:', err);
+    return [];
+  });
+}
+
+export function refreshProviderSnapshot(cwd?: string): Promise<ProviderSnapshotEntry[]> {
+  cached = null;
+  inflight = null;
+  return doFetch(cwd);
+}
+
+export function useProviderSnapshot(cwd?: string): ProviderSnapshotEntry[] | null {
+  const entries = useSyncExternalStore(subscribe, getSnapshot);
+  useEffect(() => { ensureLoaded(cwd); }, [cwd]);
+  return entries;
+}