feat(pipeline): add stop and prune commands to pipeline engine and CLI

- Add stop_pipeline and prune_pipelines to bin/pipeline_engine.py
- Support prefix matching and custom cancellation reason
- Wire 'super pipeline stop <run_id>' and 'super pipeline prune [--max-age H]' into bin/super-cli.py

bin/pipeline_engine.py

@@ -158,9 +158,61 @@ def fail_pipeline(run_id, reason="failed"):
         save_pipelines(data)
 
 
+def stop_pipeline(run_id, reason="cancelled_by_operator"):
+    """Manually cancel or stop an active pipeline run."""
+    data = load_pipelines()
+    # Support prefix matching
+    target_key = None
+    for k in data.keys():
+        if k == run_id or k.startswith(run_id):
+            target_key = k
+            break
+
+    if not target_key:
+        return None
+
+    entry = data[target_key]
+    entry["status"] = "canceled"
+    entry["canceled_at"] = utcnow()
+    entry["updated_at"] = utcnow()
+    entry["cancel_reason"] = reason
+    save_pipelines(data)
+    return entry
+
+
+def prune_pipelines(max_age_hours=24):
+    """Mark stale running pipeline runs older than max_age_hours as timed_out."""
+    data = load_pipelines()
+    now = datetime.now(timezone.utc)
+    pruned = []
+    for k, v in data.items():
+        if v.get("status") == "running":
+            created_str = v.get("created_at")
+            if created_str:
+                try:
+                    dt = datetime.fromisoformat(created_str.replace("Z", "+00:00"))
+                    diff_h = (now - dt).total_seconds() / 3600.0
+                    if diff_h >= max_age_hours:
+                        v["status"] = "timed_out"
+                        v["completed_at"] = utcnow()
+                        v["updated_at"] = utcnow()
+                        v["timeout_reason"] = f"stale_exceeded_{max_age_hours}h"
+                        pruned.append(k)
+                except Exception:
+                    pass
+    if pruned:
+        save_pipelines(data)
+    return pruned
+
+
 def get_pipeline(run_id):
     data = load_pipelines()
-    return data.get(run_id)
+    if run_id in data:
+        return data[run_id]
+    for k, v in data.items():
+        if k.startswith(run_id):
+            return v
+    return None
 
 
 def list_active_pipelines():
@@ -176,3 +228,4 @@ def list_pipeline_history(limit=20):
         reverse=True,
     )
     return sorted_runs[:limit]
+