Key-presence refusal at every gate: a pinned model is not enough

Owner-diagnosed: the turn gate checked only model coordinates, so a
pinned slot whose provider key was deleted passed the gate and died
mid-stream masked to 'An error occurred.' The key is now gated where
the model is — by what would RUN (env-first keyValue truth, so an
env-shadowed key passes).

- core/settings.ts: the provider_key_missing envelope family (code,
  provider, slots, human line naming the provider from AUTH_PROVIDER_KEYS
  labels) + ProviderKeyMissingError + isProviderKeyRefusal matcher.
- chat-handler turn gate: refuses 503 before beginTurn when the resolved
  conversation's provider key is gone (slots: [strong]).
- Job runner: same check via an injected dep (agent layer cannot read
  the key store) — a keyless engine refuses the spawn through the
  existing failure-shape convention, no phantom run.
- Extraction pipeline: refuseIfStagesUnready refuses BEFORE any batch
  (first offender: extractor before auditor); the trigger skips info-
  level, /api/graph/import surfaces the 503 envelope per file.
- Tests: 8 new pins (turn gate both ways, runner refusal, pipeline
  first-offender + pass-through, envelope factory, matcher); the three
  turn-driving suites seed OPENROUTER_API_KEY like any real setup.
- Doc fix: stale EXTRACTION.chunkTokens comment in the manual-extract
  route (left over from eed4b4e).

Known residual (pre-existing, flagged for master): the manual extract
route logs BOTH config refusals as console.error (fire-and-forget path);
the coverage ledger keeps everything uncovered either way.

tests/demos.test.tsx

@@ -1,3 +1,4 @@
+
 /**
  * Demo + visual artifact tests (W6) — deterministic, zero network, no real
  * Chrome:
@@ -83,6 +84,13 @@ function testRunner() {
 }
 import { artifactRenderers } from "../components/artifacts/index.ts";
 
+// The key-presence turn gate (provider-key interlude, 2026-09-25): scripted
+// turns pin openrouter per chat — the gate reads env-first truth, so the
+// key must be present in the test process like any real setup.
+process.env.OPENROUTER_API_KEY ??= "test-key-presence-gate";
+
+
+
 const JOBS_DIR = path.join(PATHS.data, "jobs");
 const createdChats: string[] = [];
 const createdJobs: string[] = [];