fix: event-loop freezes, plugin-install boot crash, tmux attach/scrollbar, Codex transcripts

- GET /api/workflows: one LEAD() window pass in a read worker (read-pool.js,
  workflow-stats.js); idx_events_session restored, idx_events_tool added
- compat-sqlite gains function/pluck/readonly so a plugin install without a
  better-sqlite3 build boots again; antigravity-usage uses db.js's Database
- install-hooks adds no checkout hooks while the agenthub plugin is enabled
  (events were doubled)
- terminal attach runs the live tmux server's own binary; the pane scrollbar
  gets a visible 2-column style, and claude panes start with
  CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN=1 so tmux keeps history to scroll
- Codex sessions' conversation in GET /api/sessions/:id/transcript
- Codex/Antigravity sessions claimed by their workspace without hooks
- UI-audit follow-ups, docs and OpenAPI

client/src/pages/ActivityFeed.tsx

@@ -113,6 +113,18 @@ const PAGE_SIZE = 50;
 // stream still refreshes, which a trailing debounce never did.
 const REFRESH_THROTTLE_MS = 1000;
 
+/** The agents on screen not asked about yet, and the sessions to ask for them. */
+export function agentsToFetch(
+  events: { session_id: string; agent_id?: string | null }[],
+  asked: ReadonlySet<string>
+): { agentIds: string[]; sessionIds: string[] } {
+  const fresh = events.filter((e) => e.agent_id && !asked.has(e.agent_id));
+  return {
+    agentIds: [...new Set(fresh.map((e) => e.agent_id as string))],
+    sessionIds: [...new Set(fresh.map((e) => e.session_id))],
+  };
+}
+
 export function ActivityFeed({ embedded = false }: { embedded?: boolean } = {}) {
   const eventCtx = useContextMenu<DashboardEvent>();
   const { t } = useTranslation("activity");
@@ -158,7 +170,7 @@ export function ActivityFeed({ embedded = false }: { embedded?: boolean } = {})
   // agent_id → subagent-facing info for the agents of the sessions on screen,
   // fetched in one call per new set of sessions (never every agent).
   const [agentInfoById, setAgentInfoById] = useState<Map<string, AgentInfo>>(() => new Map());
-  const knownAgentSessions = useRef(new Set<string>());
+  const askedAgents = useRef(new Set<string>());
 
   const pausedRef = useRef(paused);
   pausedRef.current = paused;
@@ -223,13 +235,12 @@ export function ActivityFeed({ embedded = false }: { embedded?: boolean } = {})
     load();
   }, [load]);
 
-  // Agent labels for the sessions on screen that we have not seen yet.
+  // Agent labels for agents on screen not asked about yet — keyed by agent, so
+  // a subagent spawned later in a live session gets its label too.
   useEffect(() => {
-    const missing = [...new Set(events.map((e) => e.session_id))].filter(
-      (sid) => !knownAgentSessions.current.has(sid)
-    );
+    const { agentIds, sessionIds: missing } = agentsToFetch(events, askedAgents.current);
     if (missing.length === 0) return;
-    for (const sid of missing) knownAgentSessions.current.add(sid);
+    for (const id of agentIds) askedAgents.current.add(id);
     api.agents
       .list({ session_ids: missing, limit: 5000 })
       .then(({ agents }) =>
@@ -247,7 +258,7 @@ export function ActivityFeed({ embedded = false }: { embedded?: boolean } = {})
       )
       .catch(() => {
         // Non-fatal: subagent pills fall back to the short-id label.
-        for (const sid of missing) knownAgentSessions.current.delete(sid);
+        for (const id of agentIds) askedAgents.current.delete(id);
       });
   }, [events]);