backup: limit local second-brain retention

cron_tasks/backup_secondbrain.py

@@ -1,5 +1,11 @@
 #!/usr/bin/env python3
-"""Backup-Task für Second Brain - isoliert, persistent."""
+"""Backup-Task fuer Second Brain - isoliert, persistent.
+
+Local retention is intentionally small on the OpenClaw host: keep only the
+newest two JSONL exports. Longer-term/off-host retention should be handled by
+an encrypted artifact/package workflow, not by committing raw brain exports to
+Git.
+"""
 import json, os, sys
 from pathlib import Path
 from datetime import datetime, timezone
@@ -8,14 +14,47 @@ BRAIN_DIR = Path("/root/.openclaw/workspace/second-brain")
 sys.path.insert(0, str(BRAIN_DIR))
 from src.store import EngramStore
 
+DEFAULT_KEEP_LOCAL_BACKUPS = 2
+
+def backup_sort_key(path: Path) -> tuple[float, str]:
+    return (path.stat().st_mtime, path.name)
+
+def prune_local_backups(data_dir: Path, keep: int = DEFAULT_KEEP_LOCAL_BACKUPS) -> list[str]:
+    """Keep only the newest local backup files.
+
+    Both uncompressed `.jsonl` and compressed `.jsonl.gz` exports are counted,
+    so historical compressed backups do not silently accumulate again.
+    """
+    keep = max(1, keep)
+    backups = sorted(
+        list(data_dir.glob("backup_*.jsonl")) + list(data_dir.glob("backup_*.jsonl.gz")),
+        key=backup_sort_key,
+        reverse=True,
+    )
+    removed: list[str] = []
+    for backup in backups[keep:]:
+        backup.unlink()
+        removed.append(str(backup))
+    return removed
+
 def main():
     brain_db = os.environ.get("BRAIN_DB", str(BRAIN_DIR / "data" / "brain.sqlite"))
+    keep_local = int(os.environ.get("SECOND_BRAIN_BACKUP_KEEP_LOCAL", str(DEFAULT_KEEP_LOCAL_BACKUPS)))
     store = EngramStore(brain_db)
     ts = datetime.now(timezone.utc).strftime("%Y%m%d_%H%M%S")
     backup_path = Path(brain_db).parent / f"backup_{ts}.jsonl"
     count = store.export_jsonl(str(backup_path))
-    result = {"timestamp": datetime.now(timezone.utc).isoformat(), "backup_path": str(backup_path), "count": count, "success": True}
+    removed = prune_local_backups(Path(brain_db).parent, keep_local)
+    result = {
+        "timestamp": datetime.now(timezone.utc).isoformat(),
+        "backup_path": str(backup_path),
+        "count": count,
+        "removed_old_backups": removed,
+        "keep_local": keep_local,
+        "success": True,
+    }
     print(f"BACKUP: {count} Engramme -> {backup_path}")
+    print(json.dumps(result, ensure_ascii=True))
     return 0
 
 if __name__ == "__main__":