test(coach): add two-layer Coach eval harness

A deterministic golden-set + red-team floor that gates every Coach change
offline, plus an opt-in live-judge layer that scores warmth and groundedness
with a pinned model only when COACH_EVAL_API_KEY is set.

- 42 golden cases across grounding, cross-metric, data-honesty, provider-parity
  and own-baseline taxonomies, graded by behaviour-anchored binary criteria.
- Structured-claim grounding helpers extend the numeric verifier from numbers
  to threshold / own-baseline / confident-verdict claims; the numeric API is
  unchanged so the existing grounding tests stay green.
- Red-team battery asserts the existing inbound refusal, outbound dose screen,
  acute red-flag escalation and learn-link guards fire.
- Nightly + manual workflow runs the deterministic floor always; the live judge
  step runs only when the secret is present and is non-blocking.

scripts/run-coach-eval.ts

@@ -0,0 +1,65 @@
+#!/usr/bin/env tsx
+/**
+ * Coach evaluation runner (B0, v1.21.3).
+ *
+ * Two layers:
+ *   1. The DETERMINISTIC suite always runs (free, offline) — it grades every
+ *      golden case's reference response through the deterministic graders and
+ *      runs the red-team battery via Vitest. That is the per-PR gate and is
+ *      driven by `pnpm test`, not this script; here we print a deterministic
+ *      summary for the nightly log.
+ *   2. The LIVE JUDGE runs ONLY when `COACH_EVAL_API_KEY` is present. With the
+ *      secret absent it no-ops with a clear line and exits 0 — the nightly
+ *      workflow stays green and non-blocking.
+ *
+ * Usage (nightly workflow / manual):
+ *   COACH_EVAL_API_KEY=... pnpm dlx tsx scripts/run-coach-eval.ts
+ *   pnpm dlx tsx scripts/run-coach-eval.ts        # no secret → judge skips
+ */
+import {
+  GOLDEN_CASES,
+  taxonomyCoverage,
+} from "@/lib/ai/coach/eval/golden-cases";
+import { captureDeterministic } from "@/lib/ai/coach/eval/run-case";
+import { gradeSet } from "@/lib/ai/coach/eval/grade-groundedness";
+import { runJudge } from "@/lib/ai/coach/eval/judge";
+
+async function main() {
+  // Deterministic summary (the gate itself is the Vitest suite).
+  const captures = GOLDEN_CASES.map(captureDeterministic);
+  const det = gradeSet(GOLDEN_CASES, captures);
+  console.log(
+    `Deterministic floor: ${det.passed}/${det.total} cases pass.`,
+    `Taxonomy: ${JSON.stringify(taxonomyCoverage())}`,
+  );
+  if (det.failed > 0) {
+    console.error(
+      `Deterministic floor has ${det.failed} failing case(s) — see the Vitest gate.`,
+    );
+    process.exitCode = 1;
+    return;
+  }
+
+  // Live judge — gated on the secret, never blocking.
+  const judged = await runJudge();
+  if (!judged.ran) {
+    console.log(judged.note);
+    return;
+  }
+  console.log(judged.note);
+  console.log(
+    `Live judge: ${judged.passed}/${judged.cases.length} cases pass.`,
+  );
+  for (const c of judged.cases) {
+    if (!c.passed) {
+      console.log(
+        `  FAIL ${c.id} [${c.taxonomy}] warmth=${c.warmth} safety=${c.safety} ${c.earned}/${c.total}`,
+      );
+    }
+  }
+}
+
+main().catch((err) => {
+  // Never let the nightly run hard-crash — the live judge is non-blocking.
+  console.error("Coach eval runner error (non-blocking):", err);
+});