Port TypeScript PR#61813: Implement new tsc --init template

[Copilot]

This PR ports the changes from microsoft/TypeScript#61813, which updates the tsc --init command to generate a new, more modern and opinionated tsconfig.json template.

Changes

New Template Structure

The new tsconfig.json template is organized into clear sections with opinionated defaults:

{
  // Visit https://aka.ms/tsconfig to read more about this file
  "compilerOptions": {
    // File Layout
    // "rootDir": "./src",
    // "outDir": "./dist",

    // Environment Settings
    // See also https://aka.ms/tsconfig/module
    "module": "nodenext",
    "target": "esnext",
    "types": [],
    // For nodejs:
    // "lib": ["esnext"],
    // "types": ["node"],
    // and npm install -D @types/node

    // Other Outputs
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,

    // Stricter Typechecking Options
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,

    // Style Options (commented out as optional)
    // "noImplicitReturns": true,
    // ...

    // Recommended Options
    "strict": true,
    "jsx": "react-jsx",
    "verbatimModuleSyntax": true,
    "isolatedModules": true,
    "noUncheckedSideEffectImports": true,
    "moduleDetection": "force",
    "skipLibCheck": true,
  }
}

Implementation

• Added GenerateTSConfig function in internal/tsoptions/commandlineparser.go that generates the structured template with helper functions to format compiler option values
• Updated init handler in internal/execute/tsc.go to call the new function and display a success message
• Added writeConfigFile function that creates the tsconfig.json file and handles errors when the file already exists

Key Differences from Previous Template

• More opinionated: Enables modern best practices by default (strict, verbatimModuleSyntax, isolatedModules, etc.)
• Better organized: Clear sections with descriptive comments
• Focused output: Fewer commented options, showing only the most relevant settings
• Modern defaults: Uses nodenext module resolution and esnext target

Testing

• ✅ All existing tests pass with no baseline changes
• ✅ Generated output matches TypeScript baseline exactly (verified with MD5 checksums)
• ✅ Error handling works correctly when tsconfig.json already exists

Notes

This is a ground-up reimplementation rather than a line-by-line port, as suggested in the issue, due to structural differences between the TypeScript and Go implementations. The output matches the TypeScript version exactly.

Co-authored-by: RyanCavanaugh [email protected]

Original prompt

Re-implement the tsc --init update from TypeScript PR#61813. This will be difficult to port line-by-line, so prefer more of a ground-up reimplementation of the same endgoal

Note

Custom agent used: Strada to Corsa Port Expert
A Go and TypeScript expert who can easily figure out how to port PRs from one language to another

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