diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74fc4574..5ea59846 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,12 @@ and this project uses [Calendar Versioning](https://calver.org/) in the format
   the hook engine, not tied to Claude Code permission rules), conservative
   (unparseable targets are blocked, not allowed), and skips `drone rm` itself.
   This makes the safe-delete path discoverable at the moment of friction. (#630)
+- **Hook engine logs `agent_type` / `agent_id` per fire** — the engine now
+  records which agent triggered each hook (e.g. `agent=main` vs `agent=Explore`)
+  in both `engine.jsonl` and the prax monitor stream. Previously the payload
+  flowed into handlers but was never logged, leaving no way to tell an internal
+  main-turn fire from a real sub-agent fire. Pure visibility; no behavior change.
+  Groundwork for #606. (#606)
 
 ### Changed
 
diff --git a/src/aipass/hooks/apps/modules/engine.py b/src/aipass/hooks/apps/modules/engine.py
index fa615f90..7f656ae9 100644
--- a/src/aipass/hooks/apps/modules/engine.py
+++ b/src/aipass/hooks/apps/modules/engine.py
@@ -139,9 +139,10 @@ def dispatch(event_type: str, stdin_data: str, config: dict) -> str:
             result = _run_hook(command, stdin_data, timeout_s=hook_timeout)
 
         logger.info(
-            "[HOOKS] %s.%s exit=%d out=%db %dms",
+            "[HOOKS] %s.%s agent=%s exit=%d out=%db %dms",
             event_type,
             hook_name,
+            parsed.get("agent_type", "") or "main",
             result["exit_code"],
             len(result["stdout"]),
             result["elapsed_ms"],
@@ -151,6 +152,8 @@ def dispatch(event_type: str, stdin_data: str, config: dict) -> str:
                 "ts": time.time(),
                 "event": event_type,
                 "hook": hook_name,
+                "agent_type": parsed.get("agent_type", ""),
+                "agent_id": parsed.get("agent_id", ""),
                 "exit_code": result["exit_code"],
                 "elapsed_ms": result["elapsed_ms"],
                 "stdout_len": len(result["stdout"]),