tsconfig.base.json

{
  "compilerOptions": {
    /* Language and Environment */
    "target": "ES2017",
    "lib": ["ES2017", "DOM", "DOM.Iterable"],
    "jsx": "react",

    /* Modules */
    "module": "ESNext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "esModuleInterop": true,

    /* JavaScript Support - Allow .js and .ts files side by side */
    "allowJs": true,
    "checkJs": false,

    /* Emit - Babel handles transpilation, so we don't emit */
    "noEmit": true,
    "declaration": false,

    /* Interop Constraints */
    "isolatedModules": true,
    "allowSyntheticDefaultImports": true,
    "forceConsistentCasingInFileNames": true,

    /* Type Checking - Start with relaxed settings for gradual migration */
    "strict": false,
    "noImplicitAny": false,
    "strictNullChecks": false,
    "skipLibCheck": true
  }
}