tsconfig.json

{
  // ---------------------------------------------------------------------------
  // Root / solution tsconfig.
  //
  // This file is the SHARED, RUNTIME-NEUTRAL BASE for every package in the
  // monorepo and the solution file for the emitting Node packages. Expo and MCP
  // are checked by their package-local commands because they use different
  // module-resolution and emit contracts.
  //
  // Design:
  //   * The root intentionally does NOT extend `expo/tsconfig.base`. The Expo
  //     base sets `customConditions: ["react-native"]`, which is only valid
  //     with bundler/node16/nodenext module resolution and therefore conflicts
  //     with the Node/CommonJS packages (backend, shared-types) that resolve
  //     with `moduleResolution: "node"`. Leaking it into every package caused
  //     `TS5098`. Instead, the Expo frontend extends BOTH this base AND
  //     `expo/tsconfig.base` (array `extends`), so the React-Native
  //     condition lands only where bundler resolution is in effect.
  //   * Each package's tsconfig `extends` this file and overrides ONLY what it
  //     genuinely needs (see per-package comments). The defaults below are the
  //     "type-check only" baseline (`noEmit: true`); packages that actually
  //     emit JS (backend, shared-types) deliberately flip
  //     `noEmit` and pick the module/target their runtime requires.
  // ---------------------------------------------------------------------------
  "compilerOptions": {
    // Language target shared by every package. Backend (Node/Bun) and the
    // Expo apps are all comfortable with ES2020.
    "target": "ES2020",
    "lib": ["ES2020"],

    // Default module system for the type-check baseline. Emitting Node packages
    // override this with the format their runtime requires (commonjs); Expo
    // apps inherit `module: "preserve"` from the Expo base they also extend.
    "module": "ES2020",
    "moduleResolution": "bundler",

    // Correctness / safety defaults applied everywhere.
    "strict": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "resolveJsonModule": true,

    // NOTE: `isolatedModules` is intentionally NOT set in this shared base.
    // The `tsc`-emitting Node packages (backend, shared-types) historically
    // compiled without it, and enabling it globally would retroactively enforce
    // `export type` on existing re-exports (TS1205). The Expo apps already get
    // single-file-transpile safety from Metro's bundler. Keep this an explicit,
    // documented absence rather than an accidental on/off divergence.

    // Project-reference defaults. `composite` is required for any project that
    // is referenced; declaration + maps make cross-package type resolution and
    // go-to-definition work without rebuilding sources.
    "composite": true,
    "declaration": true,
    "declarationMap": true,
    "sourceMap": true,

    // The root itself never emits — it only orchestrates references and is the
    // default for editor/CLI type-checking. Emitting packages override this.
    "noEmit": true
  },
  "references": [
    { "path": "./packages/shared-types" },
    { "path": "./packages/backend" }
  ],
  "exclude": [
    "node_modules",
    "**/node_modules",
    "**/dist",
    "**/build",
    "**/.expo"
  ]
}