MutateGate: batch rollback does not undo rename_id on failure #27

Summary

When a Tier A / MutateGate batch fails mid-commit, the except MemNetError path restores deleted rows, reverts added ids, and puts back replaced snapshots — but it does not reverse successful rename_id operations that ran earlier in the same batch.

Evidence

• parts/common/memnet/memnet/mutate_gate.py: rollback block restores deleted_backup, added, and replaced only (approx. lines 355–368).
• Rename loop calls self.ss.store.rename_id(...) before mark_written(); a later failure leaves the store partially re-keyed while the caller sees a rejected batch.

Impact

Agents may retry against stale ids; graph integrity can diverge from ack expectations on multi-step update batches mixing patch, drop, and id= rename lines.

Suggested direction

Track rename pairs applied in the batch and invert them on rollback (or defer renames until end of batch with a single commit point).

Note

Unrelated to v0.3.6 serve hardening (3c537c7); still open on current master.