Conformance

An implementation is ANVIL v1 conformant if:

1. parse never throws, for any input, including every prefix of every fixture.
2. Unknown kinds, sigils, attributes and field types degrade with a warning rather than being dropped silently or throwing.
3. Derived ids depend only on content.
4. Blocks render inert while the fence is incomplete.
5. swatch, font, img and min are allowlisted; everything else is escaped.
6. If it implements stamping: the five laws hold, stamps are idempotent on (blockId, nonce), and expiry is enforced server-side.
7. If it delivers stamps to a model: they are framed as untrusted data.
8. Every number a @card or @board draws is counted from its rows. No attribute can set, override or contradict one.
9. A @card renders as a snapshot and never refreshes itself, and subtask detail is reachable without a pointer.
10. Layout collapses against its container, has no id, and never renders an interactive affordance of any kind.
11. A @chart prints every value it draws, keeps every value inside its range whatever min= and max= say, and announces a floor that is not zero.
12. A @flow terminates on a cyclic graph, draws the back edges rather than dropping them, and states the count of anything it did not draw.

Reference implementation: packages/parser and packages/render-html.