test(827): capture Gate0 runtime evidence

docs/compaction-refresh/probes/p1_hook_client.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""Claude SessionStart hook client for P1 ancestry evidence."""
+
+from __future__ import annotations
+
+import json
+import os
+import socket
+import sys
+
+
+def main() -> None:
+    # Consume the real Claude hook payload without recording transcript paths or
+    # prompt content in the evidence artifact.
+    hook_input = json.load(sys.stdin)
+    conn = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+    conn.connect(os.environ["GATE0_BROKER_SOCKET"])
+    conn.sendall((json.dumps({"action": "resolve-hook"}) + "\n").encode())
+    response = json.loads(conn.makefile("r", encoding="utf-8").readline())
+    conn.close()
+    event_name = hook_input.get("hook_event_name")
+    if response.get("decision") != "ACCEPT":
+        print(f"Gate0 broker rejected {event_name} hook ancestry", file=sys.stderr)
+        raise SystemExit(2)
+    print(
+        json.dumps(
+            {
+                "hookSpecificOutput": {
+                    "hookEventName": event_name,
+                    "additionalContext": "GATE0_P1_SUPPORTED_HOOK_ANCESTRY_ACCEPTED",
+                }
+            }
+        )
+    )
+
+
+if __name__ == "__main__":
+    main()