admin: cheap ungated /healthz; dashboard probes it (no probe storm) + live screenshot

Downstream polish. The dashboard auto-discovers admin and, by default,
probed it at its /admin prefix — but admin's page awaits a full snapshot
(probing every sibling) on render, so the probe blew the 3s timeout and
admin read as 'down' (and two ops consoles probing each other could
storm). Add admin GET <prefix>/healthz: a cheap, ungated liveness endpoint
(200 { status, uptime_seconds }, no snapshot, no auth — conventional, like
metrics/). serve.js + compose.test.js refine the dashboard's admin probe
to /admin/healthz. Now the live demo shows every one of 32 auto-discovered
plugins alive (screenshot added to dashboard/README).

admin/test.js: healthz is 200 and ungated even when the page is gated.

Author: melvincarvalho

admin/plugin.js

@@ -565,6 +565,16 @@ ${NOT_POSSIBLE.map(([what, why]) => `      <li><strong>${esc(what)}</strong> —
     return snapshot();
   });
 
+  // Cheap, ungated liveness — no snapshot, no auth (conventional for a
+  // healthz, like metrics/). It lets another prober (e.g. dashboard/) confirm
+  // the admin plugin is alive WITHOUT triggering a full page-snapshot render,
+  // which probes every sibling and would otherwise blow the prober's timeout
+  // and read as 'down' — and, when two ops consoles probe each other, storm.
+  api.fastify.get(`${prefix}/healthz`, async (request, reply) => {
+    reply.header('cache-control', 'no-store');
+    return { status: 'ok', uptime_seconds: Math.round(process.uptime()) };
+  });
+
   if (!adminAgents) {
     api.log.warn(
       `admin: the admin surface at ${prefix}/ is OPEN — no config.adminAgents set, `

admin/test.js

@@ -181,6 +181,17 @@ describe('admin plugin', () => {
     }
   });
 
+  it('healthz is 200 and ungated — liveness needs no auth, even when the page is gated', async () => {
+    // The page and status.json are gated (above), but healthz must answer
+    // anonymously so another prober (dashboard/) can check liveness cheaply
+    // without triggering a full snapshot render.
+    const res = await get(`${base}/admin/healthz`);
+    assert.strictEqual(res.status, 200, `healthz: ${res.status}`);
+    const body = await res.json();
+    assert.strictEqual(body.status, 'ok');
+    assert.strictEqual(typeof body.uptime_seconds, 'number');
+  });
+
   // ------------------------------------------------------------- the page
 
   it('admin GET page → 200 self-contained HTML with plugin ids, pods count, sections', async () => {

compose.test.js

@@ -136,6 +136,9 @@ describe('composition: every plugin on one server', () => {
             probes: {
               relay: { kind: 'ws' }, webrtc: { kind: 'ws' }, terminal: { kind: 'ws' },
               tunnel: { kind: 'ws' }, notifications: { kind: 'ws' },
+              // admin probes every plugin on page render; hit its cheap
+              // healthz so the two ops consoles don't storm each other.
+              admin: { probe: '/admin/healthz', expect: [200] },
             },
           },
         },

dashboard/README.md

@@ -75,6 +75,13 @@ optionally refines a single plugin's probe as `{ probe?, expect?, kind? }`:
 - If the dashboard is the only plugin loaded, the page renders with a note
   explaining there are no siblings to show.
 
+![The dashboard auto-discovering and probing 32 plugins live on one server](./screenshot.png)
+
+*Live `/dashboard/` from `npm run serve` — 32 plugins auto-discovered via
+`api.plugins`, each probed over loopback. `up` = 2xx/3xx or a matched
+`expect`; `degraded` = a 4xx from a guarded surface (alive, but a bare-prefix
+probe can't say more — finding 1's residual); nothing `down`.*
+
 ### The page, in words
 
 A single narrow column, system font, honest table: **plugin | probe |

dashboard/screenshot.png

@@ -157,6 +157,9 @@ const fastify = createServer({
           relay: { kind: 'ws' }, webrtc: { kind: 'ws' }, terminal: { kind: 'ws' },
           tunnel: { kind: 'ws' }, notifications: { kind: 'ws' },
           pay: { probe: '/paid/demo', expect: [402] },
+          // admin's page probes every plugin on render; hit its cheap healthz
+          // instead so the probe is fast and the two consoles don't storm.
+          admin: { probe: '/admin/healthz', expect: [200] },
         },
       },
     },