Use detect-monorepo for workspace root and rush detection

[0x80]

Use detect-monorepo to auto-detect the workspace root, replacing the hardcoded workspaceRoot: "../.." default.

When workspaceRoot is not set explicitly (and targetPackagePath is not used), resolveWorkspacePaths now walks upward from the target package directory looking for pnpm-workspace.yaml, a package.json with a workspaces field, or rush.json. If detection fails and no workspaceRoot is configured, a clear error asks the user to set it explicitly.

The workspaceRoot config option remains supported as an override for cases where auto-detection fails (e.g. unusually deep nesting).

The existing isRushWorkspace helper is kept as a strict rush.json check at the passed-in directory. It is intentionally not replaced with detectMonorepo, because detectMonorepo walks upward and its rootDir can diverge from workspaceRootDir, which would break callers that compute lockfile importer ids or other paths relative to the same directory.

Docs and CLI help text updated to reflect the new auto-detect behavior.

Scope: packages (isolate-package)
Visibility: user-facing

[Copilot]

Pull request overview

This PR replaces the repo’s manual monorepo/Rush detection and the hardcoded workspaceRoot: "../.." default with detect-monorepo, so the workspace root can be auto-detected by walking upward from the target package directory (unless explicitly overridden).

Changes:

• Replace the is-rush-workspace helper with detectMonorepo(dir)?.kind === "rush" at Rush-specific branches.
• Update resolveWorkspacePaths to auto-detect workspaceRootDir when workspaceRoot is omitted and targetPackagePath isn’t used, throwing a clearer error on failure.
• Update CLI/docs to describe auto-detection, and adjust unit tests to mock detect-monorepo.

Reviewed changes

Copilot reviewed 17 out of 18 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/lib/utils/is-rush-workspace.ts	Removes the old Rush detection helper.
src/lib/utils/index.ts	Stops exporting the removed helper.
src/lib/registry/create-packages-registry.ts	Uses detect-monorepo to branch for Rush workspaces when enumerating packages.
src/lib/patches/copy-patches.ts	Uses detect-monorepo to select Rush vs non-Rush lockfile location for patch hash extraction.
src/lib/patches/copy-patches.test.ts	Mocks detect-monorepo for patch-copy tests.
src/lib/package-manager/index.ts	Uses detect-monorepo for Rush-aware package manager detection.
src/lib/manifest/helpers/adopt-pnpm-fields-from-root.ts	Skips pnpm-field adoption for Rush via detect-monorepo.
src/lib/manifest/helpers/adopt-pnpm-fields-from-root.test.ts	Updates mocks/assertions to use detect-monorepo.
src/lib/lockfile/helpers/generate-yarn-lockfile.ts	Uses detect-monorepo to locate Rush Yarn lockfile.
src/lib/lockfile/helpers/generate-pnpm-lockfile.ts	Uses detect-monorepo to locate Rush PNPM lockfile directory.
src/lib/lockfile/helpers/generate-pnpm-lockfile.test.ts	Mocks detect-monorepo for PNPM lockfile generation tests.
src/lib/config.ts	Makes workspaceRoot optional; adds auto-detection + error when missing.
src/isolate.ts	Uses detect-monorepo to decide Rush-specific pnpm workspace generation behavior.
src/isolate-bin.ts	Updates --workspace-root help text and examples for auto-detection.
pnpm-lock.yaml	Locks the new detect-monorepo dependency.
package.json	Adds detect-monorepo to dependencies.
docs/configuration.md	Updates workspaceRoot docs to reflect auto-detection.
docs/api.md	Updates config examples to no longer rely on workspaceRoot defaults.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

Comments suppressed due to low confidence (4)

src/lib/registry/create-packages-registry.ts:80

• detectMonorepo(workspaceRootDir) can return a Rush monorepo whose rootDir is above the provided directory. In that case this branch will still run, but rush.json is read from workspaceRootDir instead of the detected root, which can cause a runtime read error or incorrect project listing. Consider using the returned rootDir for the Rush-specific paths (or require detected.rootDir === workspaceRootDir before treating it as Rush).

  if (detectMonorepo(workspaceRootDir)?.kind === "rush") {
    const rushConfig = readTypedJsonSync<RushConfig>(
      path.join(workspaceRootDir, "rush.json"),
    );

src/lib/patches/copy-patches.ts:157

• detectMonorepo(workspaceRootDir) may detect a Rush monorepo with rootDir different from the provided workspaceRootDir (since it walks upward). If that happens, lockfileDir will be computed relative to the wrong base directory. Consider basing Rush-specific paths on detectMonorepo(...).rootDir (or only treating it as Rush when the detected root matches workspaceRootDir).

  try {
    const { majorVersion } = usePackageManager();
    const useVersion9 = majorVersion >= 9;
    const isRush = detectMonorepo(workspaceRootDir)?.kind === "rush";

    const lockfileDir = isRush
      ? path.join(workspaceRootDir, "common/config/rush")
      : workspaceRootDir;

src/lib/package-manager/index.ts:30

• detectMonorepo(workspaceRootDir) can return a Rush monorepo whose rootDir is above workspaceRootDir. In that scenario, common/config/rush will be looked up under the wrong directory. Consider using const detected = detectMonorepo(workspaceRootDir) and basing the Rush lockfile/metadata directory on detected.rootDir (or requiring detected.rootDir === workspaceRootDir).

export function detectPackageManager(workspaceRootDir: string): PackageManager {
  if (detectMonorepo(workspaceRootDir)?.kind === "rush") {
    packageManager = inferFromFiles(
      path.join(workspaceRootDir, "common/config/rush"),
    );
  } else {

src/lib/lockfile/helpers/generate-pnpm-lockfile.ts:72

• isRush is derived from detectMonorepo(workspaceRootDir)?.kind, but the Rush lockfile directory is still constructed from workspaceRootDir. Because detectMonorepo walks upward, it can report Rush even when workspaceRootDir is a subdirectory; in that case the common/config/rush path will be wrong. Consider basing Rush paths on the detected rootDir (or requiring detected.rootDir === workspaceRootDir).

  try {
    const isRush = detectMonorepo(workspaceRootDir)?.kind === "rush";

    const lockfile = useVersion9
      ? await readWantedLockfile_v9(
          isRush
            ? path.join(workspaceRootDir, "common/config/rush")
            : workspaceRootDir,
          {
            ignoreIncompatible: false,
          },
        )
      : await readWantedLockfile_v8(
          isRush
            ? path.join(workspaceRootDir, "common/config/rush")
            : workspaceRootDir,
          {
            ignoreIncompatible: false,

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated 2 comments.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

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