ai: show AI's resting sentence in Vibe's stream answer (#621)

ddiff --git a/server/ai/ai-service.js b/server/ai/ai-service.js
iindex e9d32be4..97a49464 100644
---- a/server/ai/ai-service.js
++++ b/server/ai/ai-service.js
@@@ -47,6 +47,15 @@ function warn(msg) {
      console.warn(`[AI service] ${msg}`);
  }
  
++/**
++ * The last problem AI answered with, for the caller that shows it to a person: today only `ai.resting` (503:
++ * every provider is out of balance, paused or busy). A product asks this instead of inventing an error, and
++ * shows the human sentence AI sent. Cleared when a run succeeds.
++ */
++let _lastProblem = null;
++function lastProblem() { return _lastProblem; }
++const RESTING = { code: 'ai.resting', detail: 'AI is resting for a moment' };
++
  async function _fetchJson(method, path, body, timeoutMs, retried = false) {
      let headers;
      try { headers = await principal.serviceHeaders(AUDIENCE); } catch (e) { warn(`no service token for ${AUDIENCE}: ${e.message}`); return null; }
@@@ -65,7 +74,12 @@ async function _fetchJson(method, path, body, timeoutMs, retried = false) {
          return await _fetchJson(method, path, body, timeoutMs, true);
      }
      if (res.status === 429) { warn(`quota: ${(json && json.detail) || 'refused'} (retry after ${res.headers.get('retry-after') || '?'}s)`); return null; }
--    if (!res.ok && res.status !== 202) { warn(`${method} ${path} -> ${res.status} ${(json && (json.code || json.detail)) || ''}`); return null; }
++    if (!res.ok && res.status !== 202) {
++        // AI is resting (ai.resting): keep its sentence so a product can show it instead of "could not answer".
++        if (res.status === 503 && json && json.code === 'ai.resting') _lastProblem = { ...RESTING, retry_after_seconds: Number(res.headers.get('retry-after')) || null };
++        warn(`${method} ${path} -> ${res.status} ${(json && (json.code || json.detail)) || ''}`);
++        return null;
++    }
      return json;
  }
  
@@@ -75,6 +89,7 @@ async function _fetchJson(method, path, body, timeoutMs, retried = false) {
   */
  async function run(workflow, input, { target, attribution, idempotencyKey, waitMs = 60000, pollMs = 0, credentialSubject = null } = {}) {
      if (!enabled()) return null;
++    _lastProblem = null;
      const wait = Math.max(0, Math.min(60000, waitMs));
      const created = await _fetchJson('POST', `/api/v1/runs?wait=${wait}`, {
          workflow, input, target: target || undefined, attribution: attribution || undefined, idempotency_key: idempotencyKey || undefined,
@@@ -91,6 +106,7 @@ async function run(workflow, input, { target, attribution, idempotencyKey, waitM
          if (!again || !again.run) return null;
          r = again.run;
      }
++    if (r.error && r.error.code === 'ai.resting') _lastProblem = { ...RESTING, detail: r.error.detail || RESTING.detail };
      return r;
  }
  
@@@ -181,4 +197,4 @@ async function complete(o = {}, { toVisionJpeg } = {}) {
      };
  }
  
--module.exports = { enabled, run, structured, complete, usable, meter, imageInput, ownerRef, workflowFor, setRecorder, KIND_TO_WORKFLOW, AUDIENCE };
++module.exports = { enabled, run, structured, complete, usable, meter, imageInput, ownerRef, workflowFor, setRecorder, lastProblem, KIND_TO_WORKFLOW, AUDIENCE };
ddiff --git a/server/ai/vibe-voice.js b/server/ai/vibe-voice.js
iindex 535eab7b..f83c7c80 100644
---- a/server/ai/vibe-voice.js
++++ b/server/ai/vibe-voice.js
@@@ -160,7 +160,14 @@ async function answer(stream, request, ev, settings, deps) {
          .catch(() => null);
      let text = r && typeof r.text === 'string' ? r.text.replace(/\s+/g, ' ').replace(/^["'“”]+|["'“”]+$/g, '').trim() : '';
      text = text.slice(0, ANSWER_MAX).trim();
--    if (!text) return say(stream, 'I couldn\'t answer that just now. Try again in a minute.', { speak: false, deps });
++    if (!text) {
++        // AI is resting (503 ai.resting: every provider is out of balance, paused or busy): show its sentence, not
++        // a generic failure. deps.problem lets a test (or another caller) supply the same state.
++        const problem = typeof deps.problem === 'function' ? deps.problem()
++            : (typeof llm.lastProblem === 'function' ? llm.lastProblem() : require('./ai-service').lastProblem());
++        const resting = Boolean(problem && problem.code === 'ai.resting');
++        return say(stream, resting ? 'AI is resting for a moment. Try again in a minute.' : 'I couldn\'t answer that just now. Try again in a minute.', { speak: false, deps });
++    }
      try {
          const wf = require('../chat/word-filter');
          if (!wf.check(text).safe) return null;
ddiff --git a/test/vibe-voice.test.js b/test/vibe-voice.test.js
iindex e4423a9c..58a7735b 100644
---- a/test/vibe-voice.test.js
++++ b/test/vibe-voice.test.js
@@@ -80,6 +80,14 @@ const voice = require('../server/ai/vibe-voice');
      done = await voice.onSpeech(stream, [speech(500, 'hey vibe clip that'), speech(520, 'okay robot, clip that')], deps);
      assert.deepStrictEqual(done.map((d) => d.start_sec), [520], 'only their word wakes it');
  
++    // AI is resting (503 ai.resting): the stream hears AI's own sentence, not a generic failure.
++    const resting = { ...deps, llm: { complete: async () => null }, problem: () => ({ code: 'ai.resting', detail: 'AI is resting for a moment' }) };
++    await voice.onSpeech(stream, [speech(600, 'okay robot, tell me a joke')], resting);
++    assert.ok(/AI is resting for a moment/.test(posted[posted.length - 1].message), posted[posted.length - 1].message);
++    const generic = { ...deps, llm: { complete: async () => null }, problem: () => null };
++    await voice.onSpeech(stream, [speech(700, 'okay robot, tell me a joke')], generic);
++    assert.ok(/couldn't answer that just now/.test(posted[posted.length - 1].message), posted[posted.length - 1].message);
++
      console.log('vibe voice: all checks passed');
      process.exit(0);
  })().catch((e) => { console.error(e); process.exit(1); });