fix: use skill activity in curator status

Treat skill views and edits as activity when curator reports and applies lifecycle transitions, so recently loaded or patched skills are not displayed or transitioned as never used.\n\nAdds regression tests for activity derivation, automatic transitions, and CLI status output.

agent/curator.py

@@ -7,7 +7,7 @@ daemon): when the agent is idle and the last curator run was longer than
 the review.
 
 Responsibilities:
-  - Auto-transition lifecycle states based on last_used_at timestamps
+  - Auto-transition lifecycle states based on derived skill activity timestamps
   - Spawn a background review agent that can pin / archive / consolidate /
     patch agent-created skills via skill_manage
   - Persist curator state (last_run_at, paused, etc.) in .curator_state
@@ -213,8 +213,8 @@ def should_run_now(now: Optional[datetime] = None) -> bool:
 
 def apply_automatic_transitions(now: Optional[datetime] = None) -> Dict[str, int]:
     """Walk every agent-created skill and move active/stale/archived based on
-    last_used_at. Pinned skills are never touched. Returns a counter dict
-    describing what changed."""
+    the latest real activity timestamp. Pinned skills are never touched.
+    Returns a counter dict describing what changed."""
     from tools import skill_usage as _u
 
     if now is None:
@@ -230,10 +230,10 @@ def apply_automatic_transitions(now: Optional[datetime] = None) -> Dict[str, int
         if row.get("pinned"):
             continue
 
-        last_used = _parse_iso(row.get("last_used_at"))
-        # If never used, treat as using created_at as the anchor so new skills
-        # don't immediately archive themselves.
-        anchor = last_used or _parse_iso(row.get("created_at")) or now
+        last_activity = _parse_iso(row.get("last_activity_at"))
+        # If never active, treat created_at as the anchor so new skills don't
+        # immediately archive themselves.
+        anchor = last_activity or _parse_iso(row.get("created_at")) or now
         if anchor.tzinfo is None:
             anchor = anchor.replace(tzinfo=timezone.utc)
 
@@ -980,10 +980,11 @@ def _render_candidate_list() -> str:
             f"- {r['name']}  "
             f"state={r['state']}  "
             f"pinned={'yes' if r.get('pinned') else 'no'}  "
+            f"activity={r.get('activity_count', 0)}  "
             f"use={r.get('use_count', 0)}  "
             f"view={r.get('view_count', 0)}  "
             f"patches={r.get('patch_count', 0)}  "
-            f"last_used={r.get('last_used_at') or 'never'}"
+            f"last_activity={r.get('last_activity_at') or 'never'}"
         )
     return "\n".join(lines)