Long-press message selection + delete (message.delete frame, outbox removal, all-device sync)

gateway-plugin/outbox.py

@@ -277,6 +277,55 @@ class Outbox:
             "oldest_message_id": oldest_message_id,
         }
 
+    # ── message deletion ──────────────────────────────────────────────────
+
+    def delete_message(
+        self,
+        chat_id: str,
+        message_id: str,
+        thread_id: Optional[str] = None,
+    ) -> int:
+        """Remove every outbox frame belonging to *message_id* in *chat_id*.
+
+        A message can span several frames (``message`` / ``message.start`` /
+        ``message.update`` / ``message.stop`` / ``media.offer`` /
+        ``commentary``); all of them are removed so neither ``history`` nor a
+        ``sync`` replay can resurrect the message. The delete is scoped to the
+        exact lane: a flat-lane delete (``thread_id=None``) matches only frames
+        with no ``thread_id``, and a thread delete matches only that thread's
+        frames (a ``message_id`` is unique to one lane, so this is a safety
+        net, not a filter that drops real frames). Returns the number of rows
+        removed (0 when the message is not in the outbox — e.g. already pruned
+        by retention).
+        """
+        if not message_id:
+            return 0
+        with self._lock:
+            rows = self._conn.execute(
+                "SELECT cursor, frame FROM outbox WHERE chat_id = ?", (chat_id,)
+            ).fetchall()
+            cursors: List[int] = []
+            for r in rows:
+                try:
+                    frame = json.loads(r["frame"])
+                except (json.JSONDecodeError, TypeError):
+                    continue
+                if not isinstance(frame, dict):
+                    continue
+                if frame.get("thread_id") != thread_id:
+                    continue
+                payload = frame.get("payload")
+                if isinstance(payload, dict) and payload.get("message_id") == message_id:
+                    cursors.append(int(r["cursor"]))
+            if not cursors:
+                return 0
+            placeholders = ",".join("?" * len(cursors))
+            self._conn.execute(
+                f"DELETE FROM outbox WHERE cursor IN ({placeholders})", cursors
+            )
+            self._conn.commit()
+            return len(cursors)
+
     # ── retention ─────────────────────────────────────────────────────────
 
     def _maybe_prune(self) -> None: