fix(mobile): generate the type declarations the tsconfig already includes

[toruiwasa]

Closes #105

apps/mobile/app.json sets experiments.typedRoutes: true and tsconfig.json includes .expo/types/**/*.ts and expo-env.d.ts — but nothing ever wrote those files, so both type gates were inert. #11 added the typecheck task that made this visible; this PR gives that compiler the declarations the configuration already claims it has.

Decision record: plans/ISSUE-105_Mobile_Generated_Types.md

What changed

"typegen":   "EXPO_NO_TYPESCRIPT_SETUP=1 expo customize tsconfig.json",
"typecheck": "pnpm run typegen && tsc --noEmit -p tsconfig.json && tsc --noEmit -p tsconfig.spec.json"

turbo.json is unchanged; .github/workflows/ci.yml changes in a comment only. Generation is the first step of the package's own typecheck script, so #11's invariant — pnpm typecheck is the gate, passes locally ⇒ passes in CI — still holds. A CI-only step would have checked something the developer's machine never checks.

expo customize tsconfig.json is what @expo/cli's type-generation/routes.js documents as the way to run typed routes without Metro or a dev server; measured at ~2.2s with no bundler process. EXPO_NO_TYPESCRIPT_SETUP=1 suppresses the prerequisite that would otherwise run expo install for typescript / @types/react — i.e. network access and a package.json write — from inside a CI check; generation does not read the variable, so the gate is unaffected.

The files are generated, not committed: router.d.ts is derived from the app/ route tree, so a committed copy goes stale as a false pass — the worst failure shape for a gate whose whole point is not being vacuous.

Live defect found and fixed

Generating the route types surfaced this from the #94 scaffold:

href: ... | `/_sitemap...` | `/__tests__/index.test...`

Expo Router turns every file under app/ into a route — _ctx.*.js's require.context regex excludes only +api / +html / +middleware, and getRoutesCore.js's ignore list adds nothing for tests. So app/__tests__/index.test.tsx was a real /__tests__/index.test route and shipped @testing-library/react-native inside the app bundle.

Tests move to apps/mobile/__tests__/. No tsconfig change was needed (**/__tests__/** matches at the project root too); collectCoverageFrom also stops counting the test file as a source file, which it had been doing.

Two of #105's premises were wrong

1. expo export does not generate these files. startTypeScriptServices has exactly two callers in @expo/cli 57.0.17 — DevServerManager (expo start) and customize/typescript.js. So typedRoutes and expo-env.d.ts are declared but never generated — both type gates are inert #105 is independent of Nothing automated exercises Metro's package-exports resolution #96, not sequenced behind it. plans/REQ-17_Task8_CI_Mobile.md carries a dated correction where that hypothesis was written.

2. A misspelled EXPO_PUBLIC_* cannot be rejected on a bare reference. expo/types/metro-require.d.ts declares ProcessEnv with an open index signature ([key: string]: string | undefined), so any name reads. Measured:

   	type of process.env.EXPO_PUBLIC_TYPO	const s: string = <that>
   without expo-env.d.ts	any	exit 0 — silent
   with expo-env.d.ts	string | undefined	exit 2, TS2322

   The achievable gate is "a misspelled variable is not a string". Declaring the real names lands with the code that reads them (Task 9 — Mobile core infrastructure (logger, supabase client, query client, auth store, constants, colors) #12).

Verified non-vacuous

Every probe was run after rm -rf .expo/types expo-env.d.ts, so it also proves generation happens inside the same typecheck invocation rather than relying on leftovers.

Probe	Result
<Redirect href="/this-route-does-not-exist" />	pnpm typecheck → exit 2, TS2322
const url: string = process.env.EXPO_PUBLIC_TYPO	pnpm typecheck → exit 2, TS2322
route added in the same run	appears in the accepted href union — generation is not stale
lint with no generated files	exit 0, generates nothing — CI's lint-before-typecheck order is safe
pnpm lint / pnpm typecheck / pnpm test	0 / 0 / 0
git status afterwards	clean — Expo rewrites tsconfig.json / .gitignore only when extends or the two include entries are missing, and ours has all three

Probes for both gates are now permanent in apps/mobile/README.md, in the exact form they were run.

Second commit — found in adversarial review

Reviewing the first commit for holes found a regression it introduced: moving the tests out of app/ moved them out of expo lint's reach. The wrapper lints only src / app / components (DEFAULT_INPUTS in @expo/cli's lint/lintAsync.js). Verified by injection — a no-var error in __tests__/index.test.tsx passed expo lint at exit 0 while the same error in app/index.tsx failed it.

Fix: "lint": "eslint ." — lints everything the flat config does not ignore, so there is no directory list to keep in sync. Explicit inputs to expo lint were rejected: unlike the defaults they skip the existence filter, so the list breaks on a missing directory and goes stale on a new one. Measured: clean pass on the current tree, exit 1 on the injected error, exit 0 with the generated files absent.

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