[HugoGresse]

Closes #1406

Why

npm run lint in functions/ did nothing: the script was "". ESLint 9 no longer reads .eslintrc.js, and eslint-config-google is no longer maintained. Running the old config by hand found about 120 warnings and 200 errors, many of them from rules that no longer exist.

#1700 moved the frontend to Biome, so functions/ now uses Biome too.

Tooling

• Config: functions/biome.json uses the recommended preset with no rules turned off, and the same formatter settings as the root biome.jsonc.
  • It is a separate root: true config because functions/ is a standalone package, and the root config excludes it.
  • Biome is pinned at 2.6.4, the latest release. The root is still on 2.5.15.
• Scripts:
  • npm run lint runs biome check --error-on-warnings (lint and format).
  • npm run format writes the formatting.
  • npm run typecheck type-checks the specs and test utilities, which the build excludes.
• CI: build.yml gains a lint functions/ step and a typecheck functions/ specs step. Both fail on any new warning or type error.
• Pre-commit: functions/package.json gets a lint-staged entry. lint-staged uses the nearest config, so staged functions files are now formatted and linted, with the same --error-on-warnings as CI.
• Removed: the ESLint dependencies, .eslintrc.js, the dead tslint.json and tsconfig.dev.json. The unused tsconfig.test.json is reused as the spec typecheck config, with bundler resolution like vitest.

Warnings fixed

Biome reported 184 diagnostics: 3 errors, 177 warnings and 4 infos. All are fixed with real code changes, and nothing is disabled.

Rule	Count	Fix
useImportType	95	import type (safe autofix; the emitted JS is identical)
noExplicitAny	55	Real types, listed below
noUnusedFunctionParameters / noUnusedVariables	13	Removed, or _-prefixed where the position is fixed (Fastify handlers, SDK hooks)
useOptionalChain	7	?. (same results for every value the types allow)
noStaticOnlyClass	5	The *Dao classes are now plain objects. Call sites and vi.spyOn(XDao, …) are unchanged.
useTemplate, useNodejsImportProtocol, useConst, noTsIgnore, noNonNullAssertion, noImplicitAnyLet, useIterableCallbackReturn, noExportsInTest	10	Direct fixes

The any fixes:

• AggregatedVote is now typed. Each vote item holds either a count or text votes keyed by vote id. It is read through getAggregatedTextVotes, which vote.ts uses for the up-vote and deletion checks.
• send() resolves to a Response. It never resolved to an Error, so the redundant instanceof Response checks are gone.
• Error handler: it uses FastifyError.
• Invites: applyInvites results are typed as WriteResult, and a redundant promise wrapper is removed.
• Specs: they use FastifyInstance, vi.mocked(send) and firestore-vitest's FakeFirestoreDatabase.
• Firestore test stub: it is typed. It now returns a missing document, instead of throwing, when the test SDK passes empty event data.

The new spec typecheck also found 4 type errors that already existed in mutations.spec.ts and resources.spec.ts. They come from gaps in the firestore-vitest typings and are fixed, with a comment each.

Behaviour

No runtime change is intended:

• main and this branch were both compiled. The JS differs only where expected: object-literal DAOs, optional chains, template literals, node:crypto, Object.entries, and the vote helper.
• vote.spec.ts covers the vote aggregation paths touched by the AggregatedVote typing. Its Vote cases also pass against main's logic.

Checks

On Node 24, from functions/:

• npm run lint: 0 diagnostics.
• npm run typecheck: clean, and it does report an error deliberately added to a spec.
• npm run build: passes.
• npx vitest run: 17 files, 272 tests pass, through both the functions config and the root config.

The Firestore rules specs in config/ were not run locally because the emulator port was taken. They are untouched.

/code-review max was run, and its findings are fixed in the last commit.

Needs a decision

• Lint now gates deploys. The firebase.json functions predeploy runs npm run lint, so a functions deploy now stops on any lint warning. Before, it ran nothing.
• Info diagnostics don't fail lint. --error-on-warnings ignores info-level suggestions such as useTemplate. Making them fail would mean raising those rules' severity in functions/biome.json.
• Biome version. functions/ pins Biome 2.6.4 while the root uses 2.5.15. Dependabot's grouped monthly PR could go red if a new minor release adds a warning-level rule.
• Swallowed errors. UserDao.getUsersByIds swallows read errors with no log, the same as before. Adding a console.warn would change runtime output, so it is left out.
• Follow-ups found during review, all pre-existing:
  • sendContactEmail answers a failed send with HTTP 500 and success: true. It also puts unescaped form input into the email HTML.
  • exportEventVotes reads the session votes with its own casts, so it could share AggregatedVote once the type moves to functions/src/types.
  • firebase-tools is loaded eagerly by deleteProject, about 1.2s on every cold start.

🤖 Generated with Claude Code

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open-feedback    Run #3148

Run Properties:   Passed #3148  •  80880023a6: fix(functions): typecheck the specs, align the hook with CI

Project	open-feedback
Branch Review	claude/issue-1406-functions-lint-4d2805
Run status	Passed #3148
Run duration	02m 26s
Commit	80880023a6: fix(functions): typecheck the specs, align the hook with CI
Committer	Hugo Gresse
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Test results
Failures	0
Flaky	0
Pending	0
Skipped	0
Passing	15
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