[prestoncabe]

Summary

Until now CI only ran builder-frontend's tests. Prettier was partly applied (29 files under src didn't match), and tsc reported 187 errors, so neither could catch problems in new code.

 run_builder_frontend_suite        # bin/run-all-tests; CI runs it as `devbox run test -- builder-frontend`
   npm test
+  npm run format:check            # prettier --check src
+  npm run typecheck               # tsc, failing only when a file exceeds its baseline
+  # every check runs, and the suite fails if any did

The type check is a per-file ratchet:

typecheck
  count tsc errors per file
  fail if any file has more than typecheck-baseline.json allows   (a new file allows 0)
  note files that improved -> `npm run typecheck -- --update` lowers the baseline

The baseline drops from 187 to 151 errors:

• @types/lodash and @types/lodash.debounce remove 13 errors.
• skipLibCheck removes the errors inside library .d.ts files. Otherwise a dependency bump (Dependabot included) could fail the ratchet.

Commits:

1. Format builder-frontend with Prettier: formatting only, 29 files. None of them is touched by Share one screening session between Preview and published screeners #586.
2. Check builder-frontend formatting and types in the test suite: the scripts, the baseline, the type packages, skipLibCheck and the suite wiring. The README documents the new scripts.

Evidence

• Before: prettier --check src listed 29 files, and tsc reported 187 errors with no way to tell which were new.
  After: devbox run test -- builder-frontend:

  Tests  389 passed (389)
  All matched files use Prettier code style!
  Type check passed: 151 type errors, none beyond the baseline.
  🎉 All selected test suites passed.
  

• I trial-merged this branch with Share one screening session between Preview and published screeners #586 in a throwaway worktree. Format check, type check and tests (389) all pass, so the two PRs can merge in either order.
• npm run build still succeeds with skipLibCheck; Vite doesn't type-check.

Merge Danger

Door: two-way

Revert the second commit to remove the checks. The formatting commit is harmless to keep.

Blast Radius: builder-frontend PRs

Open builder-frontend PRs now need Prettier-formatted code and no new type errors in the files they touch. Branches that touch any of the 29 reformatted files may need a rebase.

🤖 Generated with Claude Code