feat: add session daemon health lifecycle

.ai-work/07-session-daemon-health-lifecycle.md

@@ -1,5 +1,5 @@
 # 07. Improve session daemon health and lifecycle
 
-Status: pending
+Status: completed
 
 Add health visibility and explicit lifecycle cleanup for the long-lived session daemon.

src/server/sessiond.ts

@@ -14,6 +14,20 @@ const eventHub = new SessionEventHub();
 const sessions = new PiSessionService(eventHub);
 registerSessionRoutes(app, sessions, eventHub);
 
+app.get("/health", () => ({ ok: true, activeSessions: sessions.activeCount(), checkedAt: new Date().toISOString() }));
+
+let shuttingDown = false;
+async function shutdown(signal: NodeJS.Signals): Promise<void> {
+  if (shuttingDown) return;
+  shuttingDown = true;
+  app.log.info({ signal }, "shutting down session daemon");
+  await sessions.dispose();
+  await app.close();
+}
+
+process.once("SIGINT", (signal) => { void shutdown(signal); });
+process.once("SIGTERM", (signal) => { void shutdown(signal); });
+
 const portValue = process.env["PI_WEB_SESSIOND_PORT"];
 const port = portValue !== undefined && portValue !== "" ? Number(portValue) : undefined;
 const host = process.env["PI_WEB_SESSIOND_HOST"] ?? "127.0.0.1";

src/server/sessiond/sessionProxyRoutes.ts

@@ -16,6 +16,8 @@ export function registerSessionProxyRoutes(app: FastifyInstance, daemon = new Se
     }
   };
 
+  app.get("/api/sessiond/health", (_request, reply) => proxy({ method: "GET", url: "/api/health" }, reply));
+
   app.get<{ Querystring: { cwd?: string } }>("/api/sessions", (request, reply) => proxy(request, reply));
   app.post<{ Body: { cwd: string } }>("/api/sessions", (request, reply) => proxy(request, reply));
   app.get<{ Params: { sessionId: string } }>("/api/sessions/:sessionId/messages", (request, reply) => proxy(request, reply));

src/server/sessions/piSessionService.ts

@@ -47,6 +47,22 @@ export class PiSessionService {
     );
   }
 
+  activeCount(): number {
+    return this.active.size;
+  }
+
+  async dispose(): Promise<void> {
+    clearInterval(this.heartbeat);
+    const activeSessions = Array.from(new Set(this.active.values()));
+    this.active.clear();
+    this.activities.clear();
+    await Promise.all(activeSessions.map(async (active) => {
+      active.unsubscribe();
+      await active.runtime.session.abort();
+      await active.runtime.dispose();
+    }));
+  }
+
   async list(cwd: string): Promise<ClientSession[]> {
     const [sessions, archivedRecords] = await Promise.all([SessionManager.list(cwd), this.archiveStore.list()]);
     const archivedById = new Map(archivedRecords.filter((record) => record.cwd === cwd).map((record) => [record.sessionId, record]));