# What is built

| Feature | Status |
|---|---|
| Declaring failures, kinds and codes | Built, with the checks under [Errors](failures.md#errors). |
| `fails`, `reject`, `attempt` and handling in `match` | Built. |
| Mapping | Built: a construction's rule arms and `invalid:`, proof that a construction cannot break, a query's `missing:` and writes' `conflict:` and `empty:`, each with its kind check. |
| Faults from code | Built: `Int` and `Decimal` overflow and the recursion limit are faults at their site, and a failure keeps the path it travelled and the failure it was mapped from. |
| What the client sees | Built: the envelope, the validation details and the OpenAPI responses. |
| Concealing records | Built: a record [policy](policy.md) hides reports the code's own not-found failure, and its log says `concealed_by: policy`. |
| Logging | Not built yet. |