feat: add --package-json flag for custom package.json path

[PranavAgarkar07]

Summary

Adds --package-json <path> CLI flag to allow scanning a directory with a custom package.json location. This is useful when the project's package.json is at a non-standard path or when you want to point react-doctor at a specific workspace's package.json without changing the scan directory.

Changes

• types.ts: Added packageJsonPath?: string to DiagnoseOptions and ScanOptions
• cli.ts: Added --package-json <path> CLI option with resolveCliScanOptions mapping
• scan.ts: Added packageJsonPath to ResolvedScanOptions and mergeScanOptions; passes it to discoverProject
• discover-project.ts: discoverProject() now accepts optional packageJsonPath — uses ?? fallback to <directory>/package.json (fully backward compatible)
• index.ts: diagnose() passes options.packageJsonPath to discoverProject
• README.md: Added --package-json to CLI reference

Testing

• pnpm build ✓
• pnpm typecheck ✓
• pnpm lint ✓

Closes #32

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Note

Low Risk
Low risk: adds an optional CLI/API parameter that only affects project detection input, with a backward-compatible default to <directory>/package.json. Main risk is altered caching/detection behavior if callers pass varying paths for the same directory.

Overview
Adds support for scanning a directory using a custom package.json location via new --package-json <path> CLI flag and matching packageJsonPath option in the programmatic diagnose()/scan() APIs.

Project detection (discoverProject) now accepts an optional package.json path (defaulting to <directory>/package.json) and the CLI wiring passes this through, with README updated to document the new flag.

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[reactreview]

Note

No issues found

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[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Cache key ignores new packageJsonPath parameter

Medium Severity

The cachedProjectInfos cache is keyed only by directory, but discoverProject now accepts an additional packageJsonPath parameter. If the same directory is queried first without a custom path and then with one (or vice versa), the cache returns the stale result from the first call, silently ignoring the provided packageJsonPath. The cache key needs to incorporate packageJsonPath to distinguish these cases.

Additional Locations (1)

• packages/react-doctor/src/utils/discover-project.ts#L846-L847

 

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[cursor]

Error message reports wrong path for custom package.json

Low Severity

When a user provides a custom packageJsonPath via --package-json and the file doesn't exist, PackageJsonNotFoundError(directory) is thrown, producing "No package.json found in {directory}". This is misleading — the missing file is the user-supplied custom path, not the default <directory>/package.json. Before this change the error was always accurate; now it reports the wrong location whenever a custom path is used.

 

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[vercel]

Cache key for discoverProject only uses directory, ignoring the packageJsonPath parameter, causing incorrect cached results when the same directory is used with different package.json paths.