# harden

Docs for TrueQuery 0.1.6. Get a model or load ready to go live, with idempotency, late data, schema changes, and NULL and edge guards.

**For engineers, when a model or load is about to go live or change shape.** In Claude Code this is a `/truequery` slash command. In Muse Code, describe the task in your own words, or load the skill with `/skill truequery`. In Codex the skill isn't here yet, only the checks.

```
/truequery harden the orders load
```

It runs a review first, because hardening an unchecked query bakes the bug in. Then it works through these, each with evidence or a named `TODO`:

1. **Idempotency.** Does re-running the write change nothing, and by what mechanism?
2. **Late data.** What's the policy, and where do out-of-order rows land?
3. **Schema changes.** Do new columns stay safe, and do dropped or renamed ones have a deprecation path?
4. **NULL and edge guards.** Are join keys, filters and division denominators handled?
5. **Backfills and migrations.** What's the blast radius and the rollback, and how will row counts be verified?