# Grammar Validation

Products validate themselves against the grammar by presenting a
`GrammarComposition` — a sequence of grammar elements describing
how the experience is composed.

## The seven checks

1. **Elements recognized** — every step references a ratified
   grammar element.
2. **Ordering respected** — if both elements of a precedence appear,
   the earlier one appears first.
3. **Rationale beside decision** — if `decision` appears,
   `rationale` appears at or before it.
4. **Purpose first** — if `purpose` appears, it is at or before every
   other element.
5. **Capability outcome** — compositions that reach `decision`,
   `continuity`, or `posterity` must also name `understanding` or
   `capability`.
6. **Continuity awareness** — `posterity` cannot appear without
   `continuity`.
7. **No contradiction** — the composition does not contradict any
   ordering rule.

## How products use it

```ts
import {
  makeComposition,
  validateComposition,
} from "@/platform/stewardship/grammar";

const c = makeComposition("headsup-room-arrival", "headsup", [
  "purpose", "context", "invitation", "question",
  "understanding", "contribution", "rationale", "decision",
  "memory", "continuity", "capability", "posterity",
]);

const report = validateComposition(c);
// report.passed === true means the composition is grammatical.
```

Location:
`src/platform/stewardship/grammar/grammar-validation.ts`.