ErrorHandlerService has zero dependency on Express — it's a plain
"map an error to {status, body}" service that works identically
behind any HTTP framework. It had no business living in a package
named express-tools.
Extracted HttpError, ErrorHandlerService, and ErrorHandlingResult
into a new packages/error-tools package (same tsc-build-to-dist
pattern as shared/express-tools). express-tools now only keeps the
actual Express-specific layer: ExpressServer, wrapAsyncHandler, and
createErrorMiddleware (which adapts ErrorHandlerService, imported
from error-tools, onto Express).
- packages/error-tools: new package, depends on shared + zod
- packages/express-tools: drops zod dependency, adds error-tools
dependency for error-middleware.ts's type import
- apps/api: adds error-tools dependency; app.ts, auth.service.ts,
require-auth.ts now import HttpError/errorHandlerService from
error-tools instead of express-tools
- apps/api/Dockerfile: adds COPY for packages/error-tools in the
runtime stage
- specs/error-handling.md, specs/backend-architecture.md, README.md
updated to reflect the new package split
Verified: pnpm lint, pnpm build (all packages, correct dependency
order), pnpm test (9/9 Mocha), pnpm test:bdd (5/5 Cucumber), full
Docker rebuild + compose up (no crash-loop), curl + browser checks
of /health, unknown-route 404, signup (201), duplicate-email 409
(code 4001 EMAIL_ALREADY_IN_USE) — all going through the moved
ErrorHandlerService/HttpError correctly.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Five more explicit review points, on the same PR branch.
## Every interface key commented
Audited all 6 interfaces in the codebase. Two had partially-commented
members (violates the "every key gets /** */" rule): AuthResult
(apps/api/auth.service.ts) and SafeUserProfile (packages/shared) — both
now fully commented. The other four (AuthTokenPayload,
AuthContextValue, ErrorHandlingResult, ApiErrorResponse) were already
compliant.
## Removed the Express namespace augmentation
apps/api/src/types/express.d.ts (renamed to express-request.augment.ts
in the last round) is gone entirely. requireAuth now attaches the
authenticated profile to `res.locals.userProfile` — Express's own
built-in per-request mechanism for exactly this — typed via a new
AuthLocals interface and `Response<unknown, AuthLocals>`, instead of a
project-wide `declare global` silently changing every Request's type
whether or not it went through the middleware.
## ErrorHandlerService confirmed framework-agnostic
It already had zero Express import. Documented this explicitly (in the
package's index.ts and the new backend-architecture.md spec) as a
deliberate split: ErrorHandlerService is framework-agnostic (would work
behind Fastify too), ExpressServer/createErrorMiddleware are the actual
Express integration layer.
## packages/express-tools: server init + route/middleware utilities
New ExpressServer class, modeled on the pattern shared as a reference
(adapted, not copied 1:1 — deliberately left out the reference's custom
runtime param-type-validation system, since zod already does that job
in this codebase and running two parallel validation mechanisms would
be redundant, not "propre"):
- setupCore() — the common cors/json/cookie-parser stack
- addRoute() — registers a route, warns+skips instead of silently
double-registering the same method+path
- addMiddleware() / mountRouter() / setErrorHandler()
- listen()
- .instance — the raw Express app, for supertest
Also added wrapAsyncHandler() — forwards a thrown/rejected error from an
async handler to next(err) automatically, removing the manual
try/catch/next(err) every route needed.
apps/api/src/app.ts now builds via ExpressServer (createServer(),
consumed by both server.ts's .listen() and createApp()'s .instance for
tests). auth.routes.ts's signup/login handlers use wrapAsyncHandler
instead of manual try/catch. cookie-parser/cors moved out of apps/api's
own dependencies entirely — they're express-tools' concern now.
## assertIsNever (packages/shared/src/tools/)
Exhaustiveness-check helper for switch/if-chains over a union: takes a
`never`-typed value and throws, so a forgotten case in a later-added
union member becomes a compile error instead of a silent runtime
fallthrough. Verified for real (not just written and assumed correct):
wrote a throwaway switch missing a case and confirmed `tsc` rejects it
with the exact expected error, then deleted the scratch file. No
existing switch/if-chain over a union in the codebase yet to retrofit
it into — noted as ready for when one appears (e.g. the not-yet-built
batch-cooking calculation module or recipe-import pipeline).
## specs/ updated
New specs/backend-architecture.md — ExpressServer, wrapAsyncHandler,
the res.locals decision (with the "why not declare global" reasoning
spelled out), assertIsNever. error-handling.md and
frontend-architecture.md cross-link to it instead of duplicating.
README covers the same, briefly.
## Verification
Full lint/mocha/cucumber/build green. Re-ran `node dist/server.js`
standalone (mirrors Docker, no tsx) after the ExpressServer refactor:
/health, a 404 (numeric 4040), and a real signup + GET /me round trip
confirming res.locals-based auth actually works at runtime, not just
that tsc accepts the types.
Five explicit review points, addressed on this same PR branch (not a new
PR) per updated preference.
## No .d.ts files in the codebase
- apps/web: vite-env.d.ts removed — its /// <reference types="vite/client" />
is replaced by "types": ["vite/client"] in tsconfig.app.json, same effect.
- apps/api: src/types/express.d.ts renamed to express-request.augment.ts —
`declare global` module augmentation works identically in a plain .ts
file as long as it has a top-level import (making it a module); the
.d.ts extension wasn't doing anything for us here.
## packages/express-tools — separate package for Express tooling
Moved HttpError and ErrorHandlerService out of apps/api into a new
workspace package, plus a new createErrorMiddleware() factory (the actual
Express 4-arg error-handling middleware, previously inlined in app.ts).
apps/api now just consumes @batch-cooking/express-tools. Has a real build
(tsc -> dist/, same pattern as packages/shared) — required for the same
reason shared needed one: apps/api's Docker image runs plain `node
dist/server.js`, no tsx. apps/api/Dockerfile updated to COPY the new
package's dist alongside shared's.
## faker.js for test fixtures
apps/api/test/auth.test.ts: replaced the hardcoded "Nicolas
Lefevre"/nicolas@example.com fixture (looked like real user data) with
@faker-js/faker, generated fresh per test via buildSignupPayload().
features/step-definitions/auth.steps.ts: fakerized the filler
firstName/lastName/password used for background state the scenarios
don't actually read.
Deliberately did NOT fakerize the literal example values inside
auth.feature itself (alice@example.com etc.) — those are the readable,
illustrative Gherkin examples that are the whole point of BDD scenarios,
not real PII, and randomizing them would make the scenarios harder to
read for no real gain. Flagged this reasoning in the README in case that
call should go the other way.
Caught a real bug while wiring this up: faker.internet.email() sometimes
capitalizes parts of the address, but signupSchema/loginSchema normalize
emails to lowercase — the test fixture needs to match what's actually
stored, so buildSignupPayload() lowercases the generated email too.
Found by actually running the suite repeatedly, not just once.
## ErrorCode: numeric enum, zero hardcoded values
packages/shared/src/errors/error-codes.ts: ErrorCode is now a numeric
enum (4000 VALIDATION_ERROR, 4001 EMAIL_ALREADY_IN_USE, 4010
INVALID_CREDENTIALS, 4011 NOT_AUTHENTICATED, 4040 NOT_FOUND, 5000
INTERNAL_ERROR — grouped by family like HTTP status codes).
Audited and fixed every place that hardcoded a raw code value instead of
referencing the enum: ApiClient's fallback (`"INTERNAL_ERROR" as
ErrorCode` — would no longer even type-check once the enum went numeric,
which is exactly the point), and the Cypress mock bodies (now import
ErrorCode from @batch-cooking/shared instead of typing the string).
Cucumber's "the response error code should be {string}" step still takes
the *name* in the .feature file (readable: "EMAIL_ALREADY_IN_USE") and
resolves it to the real numeric value via ErrorCode[name] — TypeScript's
reverse enum mapping — before comparing, so the Gherkin stays readable
without the step hardcoding a number either.
## Real i18n library (i18next), not a hand-rolled label map
apps/web: added i18next + react-i18next. New locales/fr/translation.json
holds every user-facing string — not just error labels (errors.*), but
the login/signup/home pages' labels, buttons and headings too
(auth.login.*, auth.signup.*, home.*) — via useTranslation()/t() in each
page. ErrorMessageService no longer owns its own label map; it converts
the numeric ErrorCode to its enum member name and delegates the actual
lookup to i18next (errors.<MEMBER_NAME>). Adding a language is now
"add a locale file", not a code change anywhere.
## specs/ and README updated
specs/error-handling.md and specs/frontend-architecture.md rewritten for
the new package, numeric codes, and i18next. New "i18n" and "no .d.ts"
sections. README covers the same, plus a note on the faker.js scope
decision (feature-file literals excluded, on purpose).
## Verification
Full lint/mocha (x3 runs)/cucumber/build green. Re-verified
express-tools' extraction against a real risk (not just tsc passing):
ran `node dist/server.js` standalone (mirrors the Docker runtime, no
tsx) and hit /health, a 404 (confirmed numeric code 4040 over the wire),
and a real signup + duplicate-email 409 (confirmed numeric 4001). Then
re-verified the full pipeline in a real browser against native dev
servers: signup, EMAIL_ALREADY_IN_USE -> i18next -> "Cet email est déjà
utilisé" end-to-end, home page i18next interpolation
({{firstName}}/{{lastName}}) rendering correctly.
