Add debug logging to EventProcessor and activity handler registry

Logs which handlers are registered at startup and which handlers are
found/called when processing each activity.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

events/bus.py

@@ -9,6 +9,7 @@ EventProcessor dispatches when processing pending activities.
 """
 from __future__ import annotations
 
+import logging
 import uuid
 from collections import defaultdict
 from typing import Awaitable, Callable, Dict, List, Tuple
@@ -17,6 +18,8 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from shared.models.federation import APActivity
 
+log = logging.getLogger(__name__)
+
 # ---------------------------------------------------------------------------
 # Activity-handler registry
 # ---------------------------------------------------------------------------
@@ -40,6 +43,7 @@ def register_activity_handler(
     """
     key = (activity_type, object_type or "*")
     _activity_handlers[key].append(fn)
+    log.info("Registered activity handler %s.%s for key %s", fn.__module__, fn.__qualname__, key)
 
 
 def get_activity_handlers(

events/processor.py

@@ -8,6 +8,7 @@ Uses SELECT ... FOR UPDATE SKIP LOCKED for safe concurrent processing.
 from __future__ import annotations
 
 import asyncio
+import logging
 import traceback
 from datetime import datetime, timezone
 
@@ -18,6 +19,8 @@ from shared.db.session import get_session
 from shared.models.federation import APActivity
 from .bus import get_activity_handlers
 
+log = logging.getLogger(__name__)
+
 
 class EventProcessor:
     """Background event processor that polls the ap_activities table."""
@@ -92,6 +95,14 @@ class EventProcessor:
         handlers = get_activity_handlers(activity.activity_type, activity.object_type)
         now = datetime.now(timezone.utc)
 
+        log.info(
+            "Processing activity %s: type=%s object_type=%s visibility=%s actor_profile_id=%s — %d handler(s) found",
+            activity.id, activity.activity_type, activity.object_type,
+            activity.visibility, activity.actor_profile_id, len(handlers),
+        )
+        for h in handlers:
+            log.info("  handler: %s.%s", h.__module__, h.__qualname__)
+
         activity.process_state = "processing"
         activity.process_attempts += 1
         await session.flush()
@@ -103,10 +114,13 @@ class EventProcessor:
 
         try:
             for handler in handlers:
+                log.info("  calling %s.%s …", handler.__module__, handler.__qualname__)
                 await handler(activity, session)
+                log.info("  done %s.%s", handler.__module__, handler.__qualname__)
             activity.process_state = "completed"
             activity.processed_at = now
         except Exception as exc:
+            log.exception("Handler failed for activity %s", activity.id)
             activity.process_error = f"{exc.__class__.__name__}: {exc}"
             if activity.process_attempts >= activity.process_max_attempts:
                 activity.process_state = "failed"