perf(state): batch message hydration in export_all

hermes_state_portability.py

@@ -258,7 +258,22 @@ class SessionPortabilityMixin:
 
     def export_all(self, source: str = None) -> List[Dict[str, Any]]:
         """Export all sessions (with messages) as dicts, e.g. for JSONL backup."""
-        return [self._with_messages(s) for s in self.search_sessions(source=source, limit=100000)]
+        sessions = self.search_sessions(source=source, limit=100000)
+        messages_by_session = {session["id"]: [] for session in sessions}
+        session_ids = list(messages_by_session)
+        # Stay below SQLite's legacy 999-variable limit while replacing the per-session N+1 reads.
+        for start in range(0, len(session_ids), 900):
+            chunk = session_ids[start:start + 900]
+            rows = self._read_all(
+                f"SELECT * FROM messages WHERE session_id IN ({','.join('?' for _ in chunk)}) "
+                "AND active = 1 ORDER BY session_id, id",
+                chunk,
+            )
+            for row in rows:
+                messages_by_session[row["session_id"]].append(
+                    self._row_to_message_dict(row, warn_context="get_messages", summary_flag=True)
+                )
+        return [{**session, "messages": messages_by_session[session["id"]]} for session in sessions]
 
     def adopt_session_lineage_from(self, donor_db: Any, session_id: str, *, retire_donor: bool = True) -> Dict[str, Any]:
         """Adopt *session_id*'s full compression lineage from *donor_db* (stranded-bot-session