Summarize: LAN primary with local-Ollama rescue + in-app failure guidance

- Engine: when the primary summarizer is out of retries (or misconfigured),
  run_summarize now finishes the job on the configured rescue provider
  (SHONAR_LLM_FALLBACK_*), tags the summary with the provider that wrote it,
  and stores a human note in job.error; success clears stale notes.
- App (auto/lan): passes Ollama as the rescue provider when it is up.
- Detail screen: shows the rescue-swap note in plain words, a red
  'Summary failed' line with Settings -> Summarizer fix instructions and a
  Retry summary button on hard failure.
- Settings copy explains the fallback. 3 new pytest cases (14/14 pass);
  live E2E on 2026-09-18: sarcastic summary v6 via LAN on attempt 2.

backend/tests/test_ai_pipeline.py

@@ -110,11 +110,13 @@ class FakeLlm:
 _UNSET = object()
 
 
-def use_fakes(monkeypatch, stt=_UNSET, llm=_UNSET):
+def use_fakes(monkeypatch, stt=_UNSET, llm=_UNSET, fallback=None):
     tprov = FakeTranscriber() if stt is _UNSET else stt
     lprov = FakeLlm() if llm is _UNSET else llm
     monkeypatch.setattr(processing, "get_transcription_provider", lambda settings: tprov)
     monkeypatch.setattr(processing, "get_llm_provider", lambda settings: lprov)
+    monkeypatch.setattr(processing, "get_llm_fallback_provider",
+                        lambda settings: fallback)
 
 
 async def jobs_for(recording_id):
@@ -409,3 +411,56 @@ async def test_ai_endpoints_enforce_ownership(client, monkeypatch):
     for path in ("transcript", "summary", "jobs"):
         r = await client.get(f"/api/v1/recordings/{rec['id']}/{path}", headers=h)
         assert r.status_code == 404, path
+
+
+# --- summarize fallback to the rescue summarizer --------------------------------
+
+async def test_summarize_fallback_rescues_after_primary_exhausted(client, monkeypatch):
+    primary = FakeLlm(fail=ProviderTransientError("LLM reply was not JSON."))
+    fb = FakeLlm()
+    fb.name = "fake-ollama"
+    use_fakes(monkeypatch, FakeTranscriber(), primary, fallback=fb)
+    token = await user_tokens(client, email="m7-fb1@example.com")
+    rec = await upload_recording(client, token, client_id="m7-fb-1")
+    await processing.run_transcribe({}, rec["id"])
+    # Last try: primary out of budget -> rescue runs and the note lands in job.error.
+    await processing.run_summarize({"job_try": 3}, rec["id"])
+    job = (await jobs_for(rec["id"]))[JobType.summarize]
+    assert job.status == JobStatus.succeeded
+    assert "fake-llm" in (job.error or "") and "fake-ollama" in (job.error or "")
+    h = {"Authorization": f"Bearer {token}"}
+    s = await client.get(f"/api/v1/recordings/{rec['id']}/summary", headers=h)
+    assert s.status_code == 200
+    assert s.json()["provider"] == "fake-ollama"
+    assert fb.seen == ["hello world from the meeting"]
+
+
+async def test_summarize_fallback_also_fails_marks_job_failed(client, monkeypatch):
+    err = ProviderTransientError("LLM reply was not JSON.")
+    fb = FakeLlm(fail=ProviderTransientError("ollama down"))
+    fb.name = "fake-ollama"
+    use_fakes(monkeypatch, FakeTranscriber(), FakeLlm(fail=err), fallback=fb)
+    token = await user_tokens(client, email="m7-fb2@example.com")
+    rec = await upload_recording(client, token, client_id="m7-fb-2")
+    await processing.run_transcribe({}, rec["id"])
+    await processing.run_summarize({"job_try": 3}, rec["id"])
+    job = (await jobs_for(rec["id"]))[JobType.summarize]
+    assert job.status == JobStatus.failed
+    assert "not JSON" in job.error  # the primary's error is what we surface
+    assert fb.seen == ["hello world from the meeting"]  # fallback was tried
+
+
+async def test_summarize_keeps_retry_budget_before_fallback(client, monkeypatch):
+    # Try 1 of 3 transient: normal arq retry wins, fallback stays untouched.
+    fb = FakeLlm()
+    fb.name = "fake-ollama"
+    use_fakes(monkeypatch, FakeTranscriber(),
+              FakeLlm(fail=ProviderTransientError("boom")), fallback=fb)
+    token = await user_tokens(client, email="m7-fb3@example.com")
+    rec = await upload_recording(client, token, client_id="m7-fb-3")
+    await processing.run_transcribe({}, rec["id"])
+    with pytest.raises(ProviderTransientError):
+        await processing.run_summarize({"job_try": 1}, rec["id"])
+    job = (await jobs_for(rec["id"]))[JobType.summarize]
+    assert job.status == JobStatus.queued
+    assert fb.seen == []