Testing contract

Run the current compatibility gates locally:

./gradlew :mermaid-core:allTests :mermaid-testkit:allTests --no-daemon --offline

The tests cover Android debug/release unit targets and iOS Simulator Arm64. The testkit exposes normalized vectors for the declared beautiful-mermaid-derived subset. Core tests additionally require:

• every failure has a non-empty typed diagnostic with source location;
• unsupported headers never fall back to another family;
• unsupported body syntax never produces partial success;
• actor/node order is stable;
• arrow/operator boundaries do not consume hyphenated IDs;
• semicolon-separated statements retain physical line/column locations.

Changes to a syntax family must add an accepted fixture, a rejected fixture, and at least one right-cause negative test. Platform pixel comparisons belong in the renderer/sample gates; parser tests must not depend on font rasterization.