auditor: kb_query surfaces scrum-master reviews for files in PR diff

Wires the cohesion-plan Phase C link: the scrum-master pipeline writes
per-file reviews to data/_kb/scrum_reviews.jsonl on accept; the
auditor now reads that same file and emits one kb_query finding per
scrum review whose `file` matches a path in the PR's diff.

Severity heuristic: attempt 1-3 → info, attempt 4+ → warn. Reaching
the cloud specialist (attempt 4+) means the ladder had to escalate,
which is meaningful signal reviewers should see. Tree-split fired is
also surfaced in the finding summary.

audit.ts now passes pr.files.map(f => f.path) into runKbCheck (the
old signature dropped it on the floor). Also adds auditor/audit_one.ts
— a dry-run CLI for auditing a single PR without posting to Gitea,
useful for verifying check behavior without spamming review comments.

Verified: after writing scrum_reviews for auditor/audit.ts and
mcp-server/observer.ts (both in PR #7), audit_one 7 surfaced both as
info findings with preview + accepted_model + tree_split flag. A
scrum review for playbook_memory.rs (NOT in PR #7) was correctly
filtered out.

auditor/audit_one.ts

@@ -0,0 +1,68 @@
+// One-shot dry-run audit of a single PR. Useful for verifying check
+// behavior (kb_query scrum surfacing, inference prompts, etc.) without
+// posting to Gitea. Does NOT touch state.json and does NOT post
+// commit status or PR comments.
+//
+// Run: bun run auditor/audit_one.ts <pr-number>
+
+import { getPrSnapshot } from "./gitea.ts";
+import { auditPr } from "./audit.ts";
+
+async function main() {
+  const prNumRaw = process.argv[2];
+  if (!prNumRaw) {
+    console.error("usage: bun run auditor/audit_one.ts <pr-number>");
+    process.exit(2);
+  }
+  const prNum = Number(prNumRaw);
+  if (!Number.isFinite(prNum)) {
+    console.error(`invalid PR number: ${prNumRaw}`);
+    process.exit(2);
+  }
+
+  console.log(`[audit_one] fetching PR #${prNum}...`);
+  const pr = await getPrSnapshot(prNum);
+  console.log(`[audit_one] PR #${pr.number}: "${pr.title}" (head=${pr.head_sha.slice(0, 12)})`);
+  console.log(`[audit_one] files in diff: ${pr.files.length}`);
+  for (const f of pr.files) console.log(`  - ${f.path} (+${f.additions}/-${f.deletions})`);
+  console.log("");
+
+  const verdict = await auditPr(pr, {
+    dry_run: true,                      // no Gitea posting
+    skip_dynamic: true,                  // don't run fixture
+    skip_inference: process.env.LH_AUDITOR_SKIP_INFERENCE === "1",
+  });
+
+  console.log("\n═══ VERDICT ═══");
+  console.log(`overall:  ${verdict.overall}`);
+  console.log(`one-liner: ${verdict.one_liner}`);
+  console.log(`findings:  total=${verdict.metrics.findings_total} block=${verdict.metrics.findings_block} warn=${verdict.metrics.findings_warn} info=${verdict.metrics.findings_info}`);
+  console.log("");
+
+  // Print findings, highlighting kb_query scrum surfacing
+  const byCheck: Record<string, typeof verdict.findings> = {};
+  for (const f of verdict.findings) (byCheck[f.check] ||= []).push(f);
+
+  for (const [check, findings] of Object.entries(byCheck)) {
+    console.log(`── ${check} (${findings.length}) ──`);
+    for (const f of findings) {
+      const tag = f.severity === "block" ? "🛑" : f.severity === "warn" ? "⚠️ " : "ℹ️ ";
+      console.log(`  ${tag} [${f.severity}] ${f.summary}`);
+      if (f.summary.includes("scrum-master")) {
+        for (const e of f.evidence) {
+          console.log(`      → ${e.slice(0, 200)}`);
+        }
+      }
+    }
+  }
+
+  const scrumFindings = verdict.findings.filter(f => f.summary.includes("scrum-master"));
+  console.log("");
+  console.log(`═══ SCRUM WIRE CHECK: ${scrumFindings.length} scrum-master findings surfaced by kb_query ═══`);
+  if (scrumFindings.length === 0) {
+    console.log("  (none — either no matching scrum_reviews.jsonl rows, or files didn't match PR diff)");
+  }
+  process.exit(0);
+}
+
+main().catch(e => { console.error("[audit_one] fatal:", e); process.exit(1); });