Set Tsconfig Root Dir For Ts6

Pin the Inferred rootDir for TypeScript 6

Before TypeScript 6, a tsconfig that did not set rootDir had it inferred as the common directory of the program's non-declaration input files. TypeScript 6 changed that default to the tsconfig's own directory. A program whose files resolve outside that directory (most commonly a spec or e2e tsconfig that imports another project's source through a paths alias) now hard-fails with TS5011 or TS6059 because a file falls outside the assumed root.

For every project tsconfig*.json that does not already set rootDir (directly or through extends), this migration pins rootDir to exactly the directory TypeScript 5 would have inferred, so both compilation and emit layout stay the same under TypeScript 6. The value is computed by the TypeScript compiler itself, so it matches tsc exactly, including project-reference redirects. The pin is written even when the inferred directory already equals the tsconfig directory: inference is per-program, and a tool that compiles a subset of the config's files — ts-jest with isolatedModules builds a program per test file — re-infers a deeper common directory from that subset and fails with TS5011. Configs that cannot hit the error are skipped: ones without an output option (outDir, outFile, sourceRoot, mapRoot, or declaration + declarationDir), and ones with no input files. The migration only runs when the workspace is on TypeScript 6.

Composite projects are pinned to their own directory ("."). Under tsc a composite rootDir already defaults there, so the pin is a no-op for a real composite build — but ts-jest strips composite for its per-file transpile, and TypeScript 6 only exempts genuinely-composite programs from the containment check, so a composite spec config compiled by ts-jest still fails with TS5011 without an explicit rootDir. Pinning the own directory (rather than a deeper file-derived value) keeps the composite build's emit layout unchanged while fixing the ts-jest case.

Each config is updated on its own; the migration never writes rootDir to a shared extends base, so a config never inherits a value computed for a sibling. Because every config that emits is given its own explicit rootDir, none is left to inherit a value pinned on a base.

Sample Code Changes

Before

A libs/products/e2e/tsconfig.json whose specs import a shared library's source:

{
  "extends": "../../../tsconfig.base.json",
  "compilerOptions": {
    "outDir": "../../../dist/out-tsc"
  },
  "include": ["src/**/*.ts"]
}

After

{
  "extends": "../../../tsconfig.base.json",
  "compilerOptions": {
    "rootDir": "../../..",
    "outDir": "../../../dist/out-tsc"
  },
  "include": ["src/**/*.ts"]
}