Gate every pull request on mutation testing #31

Parent

#21

What to build

Stryker, with its Vitest runner, mutates the gate scripts (the ADR, link, manifest and boundary checks, and whatever other logic exists by then) in a required job under Pipeline Complete. The break score is the measured score minus headroom for timeout noise, and it is only ever raised. The HTML report is uploaded as an artifact.

One ADR in docs/adr/architecture/ records the measurement (mutants, runtime, score, survivors, timeouts), the chosen break score, and the trigger for moving to incremental mode on pull requests with a full scheduled run: the job taking longer than about ten minutes. The compiler's domain, application and wire code join the targets when they land.

Acceptance criteria

• The mutation job runs on every pull request and is in Pipeline Complete's needs.
• The job fails when the score drops below the break score, shown by weakening a test on a throwaway branch.
• The report artifact is uploaded and is not empty.
• The ADR states the measured numbers the break score came from.

Blocked by

• Run the suite on Vitest and make the tooling strict TypeScript #22
• Split CI into one job per gate under Pipeline Complete #23