validate

# Validate - the combined Arcgram self-check entry One call. Two questions answered between the siblings: **is the flow well-formed and coherent, AND do its `@spec` values still match the code?** Validate is a **thin wrapper**, not a new check. It imports [Checkpoint](../checkpoint/SKILL.md) and [Reconcile](../reconcile/SKILL.md) **untouched** and composes their pure functions: - **Checkpoint** (one input: the diagram) checks **structure** - well-formed, coherent. - **Reconcile** (two inputs: diagram + code) checks **values** - `@spec` literals == code constants. Run both -> the diagram is a faithful, current spec. Every finding still comes from one sibling; Validate only **merges, source-tags, and unions the attestation**. ## Code is optional | input | what runs | clean possible? | |---|---|---| | `validate(diagram, { code })` | Checkpoint **and** Reconcile | yes | | `validate(diagram)` (no code) | Checkpoint only | no - values unchecked | Without code there is nothing to reconcile, so Reconcile is **not run** (running it would just flag every `@spec` pin as missing). Instead the value half is reported as one `uncovered` `value-check-not-run` finding, so a structure-only run is never falsely "clean" on values - the same anti-silent-pass rule both siblings enforce. **Locked invariant - `uncovered` is a third state, never a pass.** A diagram-only run (no code) can **never** produce an overall green clean, even when the structure is perfect. The attestation explicitly a...