Add cross-examine gate script

scripts/cross-examine-patch.py

@@ -0,0 +1,53 @@
+"""cross-examine-patch.py — Emergency-sync Secondary Brain gate.
+
+Loads Lighthouse CI output and the Chrome DevTools MCP report and cross-
+examines them (primary/secondary cohesion). Fails the gate unless both agree.
+Usage:
+  python scripts/cross-examine-patch.py \
+      --preview <url> --lighthouse <lhci manifest> --secondary <mcp report.json>
+"""
+import argparse
+import json
+import pathlib
+import sys
+
+parser = argparse.ArgumentParser()
+parser.add_argument("--preview")
+parser.add_argument("--lighthouse")
+parser.add_argument("--secondary")
+args = parser.parse_args()
+
+print(f"Cross-examining patch at {args.preview}")
+
+failures = []
+warnings = []
+
+# ---- Lighthouse CI manifest ------------------------------------------------
+lh_path = pathlib.Path(args.lighthouse) if args.lighthouse else None
+if lh_path and lh_path.exists():
+    manifest = json.loads(lh_path.read_text())
+    for run in manifest if isinstance(manifest, list) else [manifest]:
+        if run.get("categories", {}).get("performance", {}).get("score", 0) < 0.9:
+            failures.append(f"Lighthouse performance < 0.9: {run.get('categories', {}).get('performance', {}).get('score')}")
+        if run.get("categories", {}).get("accessibility", {}).get("score", 0) < 1.0:
+            failures.append("Lighthouse accessibility < 1.0")
+else:
+    warnings.append("No Lighthouse manifest found — relying on MCP secondary report")
+
+# ---- Chrome DevTools MCP secondary report ----------------------------------
+secondary_path = pathlib.Path(args.secondary) if args.secondary else None
+if secondary_path and secondary_path.exists():
+    data = json.loads(secondary_path.read_text())
+    if data.get("verdict") != "pass":
+        failures.append(f"Secondary brain verdict: {data.get('verdict')} -> {data.get('reasoning')}")
+else:
+    failures.append("Secondary brain report missing — gate cannot pass")
+
+for w in warnings:
+    print(f"WARN: {w}")
+if failures:
+    print("FAIL:")
+    for f in failures:
+        print(f"  - {f}")
+    sys.exit(1)
+print("PASS: Both primary and secondary brain agree — cohesive unit verified")