V4.6 Phase 3: worker and provider reliability

Claim jobs atomically [CRIT-01]
- Replace JobService.read_next_queued_job with claim_next_queued_job, which
  selects and transitions QUEUED -> PROCESSING inside one transaction. The old
  read-then-write sequence left a window in which two workers could observe the
  same QUEUED row.
- Add the missing .limit(1). The poll previously ordered the entire queued set
  and discarded all but the first row.
- Drop the eager loads from the hot poll entirely. They were pure waste:
  process_queued_job immediately re-reads the job through read_job with the
  relationships it actually needs.
- Guard the row with with_for_update(skip_locked=True) on PostgreSQL so the
  claim stays correct once more than one worker exists. On SQLite the claim is a
  bounded single-writer transaction.
- Correct the comment at the remaining direct-call claim site, which described
  the hazard rather than the guarantee.

Reuse the provider connection [HIGH-02]
- Build the ServiceBundle once per worker loop instead of once per job, and
  close it at loop shutdown. Every job previously constructed a new
  SourceService, and with it a new provider adapter and a new httpx.AsyncClient,
  paying a full TLS handshake per page and discarding the connection pool.
- process_next_queued_job now accepts an optional caller-owned bundle and only
  closes bundles it created itself.

Uncap the provider timeout [HIGH-03]
- Remove le=20.0 from worker_provider_timeout_seconds. The cap equalled the
  default, so the ceiling could never be raised, and dense-page vision
  transcription routinely needs longer. Default raised to 180s.
- Pass an explicit httpx.Timeout to the OpenRouter AsyncClient. httpx defaults
  every phase to 5 seconds, so the real read budget was 5s regardless of the
  configured value; the outer asyncio.wait_for could never be the binding
  constraint. Connect stays at 10s.

Tighten the provider boundary [MED-03]
- Declare model, current_request_manifest, current_transport_evidence, and
  aclose on the TranscriptionProvider Protocol.
- Delete the per-call inspect.signature(adapter.transcribe).parameters
  reflection and the untyped kwargs dict it fed. The Protocol had declared
  requested_model all along, so the reflection was dead defensive weight on the
  hot path.
- Replace the three getattr probes for aclose and the evidence attributes with
  direct typed access.

Deduplicate bundle construction [MED-06]
- Add ServiceBundle.from_session_factory and ServiceBundle.aclose, replacing the
  duplicated four-service instantiation blocks in app.py and worker.py.
- _recover_stale_processing_jobs now uses the bundle built moments earlier
  instead of constructing a second JobService.

Tests
- Claiming returns the oldest job, marks it PROCESSING, never hands the same job
  out twice, and emits exactly one unadorned SELECT carrying LIMIT and no JOIN.
- The worker loop threads one bundle through consecutive jobs and closes it once
  at shutdown; a caller-owned bundle is left open.
- Settings accepts a timeout above 20 seconds and still rejects zero.
- The OpenRouter client's read, write, and pool timeouts track the configured
  budget rather than the httpx default.

Note: .env in this checkout still pins WORKER_PROVIDER_TIMEOUT_SECONDS=20 and
should be raised to pick up this fix.

Verified: 268 passed, 4 skipped; ruff check clean.

Co-authored-by: Copilot App <[email protected]>

tests/test_config.py

@@ -149,3 +149,28 @@ class TestWorkerReliabilitySettings:
         """worker retry settings default to no retries."""
         settings = _make_settings()
         assert settings.worker_max_retries == 0
+
+
+def test_provider_timeout_is_not_capped_at_twenty_seconds():
+    """HIGH-03: vision transcription regularly runs past the old le=20.0 ceiling."""
+    settings = Settings(openrouter_api_key="test-key", worker_provider_timeout_seconds=300.0)
+    assert settings.worker_provider_timeout_seconds == 300.0
+
+
+def test_provider_timeout_must_still_be_positive():
+    with pytest.raises(ValidationError):
+        Settings(openrouter_api_key="test-key", worker_provider_timeout_seconds=0.0)
+
+
+def test_openrouter_client_timeout_tracks_the_configured_budget():
+    """HIGH-03: httpx defaults every phase to 5s, silently capping the provider call."""
+    from transcription.providers.openrouter import OpenRouterTranscriptionProvider
+
+    settings = Settings(openrouter_api_key="test-key", worker_provider_timeout_seconds=123.0)
+    provider = OpenRouterTranscriptionProvider(settings=settings)
+    timeout = provider._capturing_client._client.timeout
+
+    assert timeout.read == 123.0
+    assert timeout.write == 123.0
+    assert timeout.pool == 123.0
+    assert timeout.connect == 10.0