wp-batch-mutation-audit

WordPress batch mutation audit

Review the correctness boundary of work split across requests or workers. Treat "the request returned success" and "the intended dataset reached the intended state exactly once" as different claims. Do not use this skill for read-only pagination; use it when rows, files, remote systems, or durable state change.

Audit workflow

1. Identify the unit of work: object ID, meta ID, custom-table primary key, file, remote delivery, or immutable snapshot row.
2. Trace selection, mutation, progress persistence, response, retry, and cleanup.
3. Model a timeout before commit, after commit but before response, and halfway through a batch.
4. Model two tabs, two admins, cron overlap, and a manual retry running together.
5. Verify every mutation result and distinguish no-op from failure.
6. Report the final-state invariant, not only individual code smells.

Critical checks

1. Lost-response ambiguity

Assume the server can commit a batch while the client receives a timeout. A browser-local offset does not prove whether that batch ran.

Flag a multi-request mutation when retry starts from zero and the operation is not naturally idempotent. Search/replace is not idempotent when replacement can match the search again: a -> aa becomes a -> aa -> aaaa on replay.

Require a durable operation record containing:

• immutable parameters and initiator;
• status (pending, running, completed, failed, cancelled);
• cursor or target snapshot;
• processed/failed counts and last error;
• timestamps and a lease/heartbeat when workers can die.

An idempotency key deduplicates operation creation. It does not by itself make each row mutation replay-safe.

2. Cursor stability

Flag mutation loops that page with increasing OFFSET over a set whose membership can change:

SELECT id FROM table
WHERE status = 'pending'
ORDER BY id
LIMIT 100 OFFSET 500;

Deleting or changing an earlier matching row shifts later offsets and can skip work. Concurrent inserts can repeat work. Prefer keyset pagination: