feat(server): /svc/status — how F is doing, for the dashboard's monitoring (F9)

What /healthz says (documents, connections, rooms) and what it keeps to
itself: the people in the rooms, the rooms each thread holds, the
process's memory, its uptime, Node's version. Behind the service key.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/server/src/service.ts

@@ -12,7 +12,8 @@
 // the dashboard sends, copy a project (as it is now, also while people work
 // in it), and give a project as a .fls (with what it could not hold, as
 // warnings in X-Filius-Warnings, base64url JSON). Snapshots and restoring come
-// with the commits (F7).
+// with the commits (F7). And how F is doing (/svc/status, F9): for the
+// dashboard's monitoring.
 
 import { createHash, timingSafeEqual } from 'node:crypto';
 import type { IncomingMessage, ServerResponse } from 'node:http';
@@ -115,6 +116,26 @@ function openDocuments(sync: Sync): { readonly user: string; readonly project: s
   return [...seen.entries()].sort(([left], [right]) => left.localeCompare(right)).map(([, open]) => open);
 }
 
+/**
+ * How F is doing, for the dashboard's monitoring (plan F9): what /healthz
+ * says — documents, connections, rooms — and what it keeps to itself: the
+ * people in the rooms, the rooms each thread holds, the process's memory
+ * and how long it has run. Behind the service key: none of it is anybody
+ * else's business.
+ */
+function statusOf(sync: Sync, sims: SimRooms) {
+  const memory = process.memoryUsage();
+  const megabytes = (bytes: number) => Math.round(bytes / 1048576);
+  return {
+    documents: sync.hocuspocus.getDocumentsCount(),
+    connections: sync.hocuspocus.getConnectionsCount(),
+    ...sims.stats(),
+    memory: { rssMb: megabytes(memory.rss), heapUsedMb: megabytes(memory.heapUsed) },
+    uptimeSeconds: Math.round(process.uptime()),
+    node: process.version,
+  };
+}
+
 export async function handleService(request: IncomingMessage, response: ServerResponse, path: string, options: ServiceOptions): Promise<void> {
   const send = (status: number, value: object) => {
     response.writeHead(status, { 'content-type': 'application/json', 'cache-control': 'no-store' });
@@ -253,5 +274,6 @@ async function route(request: IncomingMessage, path: string, { store, sessions,
     return [200, { revoked, disconnected }];
   }
   if (request.method === 'GET' && path === '/svc/sessions') return [200, { ...(await sessions.active()), open: openDocuments(sync) }];
+  if (request.method === 'GET' && path === '/svc/status') return [200, statusOf(sync, sims)];
   throw new HttpError(404, 'notFound');
 }

packages/server/test/sim.test.ts

@@ -132,6 +132,17 @@ describe('a simulation room on F', () => {
       ['sim.stop', 'ben'],
     ]);
     expect(server.sims.stats()).toEqual({ rooms: 1, people: 2, threads: [1] });
+    // What the dashboard's monitoring reads (F9): the same, and the process — only with the service key.
+    const status = await fetch(`${server.base}/svc/status`, { headers: { 'x-filius-service-key': SERVICE_KEY } });
+    expect(status.status).toBe(200);
+    const said = (await status.json()) as Record<string, unknown> & { memory: { rssMb: number; heapUsedMb: number }; uptimeSeconds: number };
+    expect(said).toMatchObject({ rooms: 1, people: 2, threads: [1], node: process.version });
+    expect(said.documents).toBeGreaterThanOrEqual(1);
+    expect(said.connections).toBeGreaterThanOrEqual(0);
+    expect(said.memory.rssMb).toBeGreaterThan(0);
+    expect(said.memory.heapUsedMb).toBeGreaterThan(0);
+    expect(said.uptimeSeconds).toBeGreaterThanOrEqual(0);
+    expect((await fetch(`${server.base}/svc/status`)).status).toBe(403);
     mia.socket.close();
     ben.socket.close();
     await server.close();