tsconfig.json

{
    "compilerOptions": {
        "target": "ES2022",
        "useDefineForClassFields": true,
        "module": "ESNext",
        "lib": ["ES2022", "DOM", "DOM.Iterable"],
        // `node` is for the build config (vite.config.ts: the git lookup and
        // the chunk-size check) and the tests that run a server or a script
        // (ecosystem-client, static-serving, check-health-json). Vite's and
        // Vitest's own types reference it too; the entry says so out loud.
        // The app itself never touches a node API.
        "types": ["vite/client", "node"],
        "skipLibCheck": true,

        /* Bundler mode */
        "moduleResolution": "bundler",
        "allowImportingTsExtensions": true,
        "verbatimModuleSyntax": true,
        "moduleDetection": "force",
        "noEmit": true,

        /* Linting */
        "strict": true,
        "noUnusedLocals": true,
        "noUnusedParameters": true,
        "erasableSyntaxOnly": true,
        "noFallthroughCasesInSwitch": true,
        "noUncheckedSideEffectImports": true
    },
    // `tests` and the vitest config are here so `tsc` covers them too: a test
    // that no longer compiles is a test that stopped guarding anything, and
    // `npm test` alone would report that as a passing suite of whatever is
    // left.
    //
    // vite.config.ts for the same reason. It holds the only build-time code in
    // the repo — the plugin that emits health.json — and Vite loads it through
    // esbuild, which strips types without checking them: a mistyped emitFile
    // option (`filename` for `fileName`) still builds cleanly and quietly
    // drops /api/health. `tsc` names that mistake; CI's health.json check
    // (scripts/check-health-json.mjs) catches whatever typing cannot.
    "include": ["src", "tests", "vitest.config.ts", "vite.config.ts"]
}