Function findChangedPackages

packages/bumpy/src/commands/check.ts:241–321

(
  changedFiles: string[],
  packages: Map<string, WorkspacePackage>,
  rootDir: string,
  config: BumpyConfig,
)

/** Map changed files to the packages they belong to */
export async function findChangedPackages(
  changedFiles: string[],
  packages: Map<string, WorkspacePackage>,
  rootDir: string,
  config: BumpyConfig,
): Promise<string[]> {
  const changed = new Set<string>();

  // Build per-package matchers (per-package patterns override root patterns)
  const matchers = new Map<string, picomatch.Matcher>();
  for (const [name, pkg] of packages) {
    const pkgConfig = await loadPackageConfig(pkg.dir, config, name);
    const patterns = pkgConfig.changedFilePatterns ?? config.changedFilePatterns;
    matchers.set(name, picomatch(patterns));
  }

  const ignoredFields = config.ignoredPackageJsonFields ?? ['devDependencies'];
  let baseRef: string | null = null; // resolved lazily, only when a package.json needs diffing

  for (const [name, pkg] of packages) {
    const pkgRelDir = relative(rootDir, pkg.dir);
    // Root package (single-package repo) has an empty relative dir — every changed
    // file belongs to it and is matched directly. Other packages only own files
    // under their own directory.
    const isRoot = pkgRelDir === '';
    const prefix = `${pkgRelDir}/`;
    const matcher = matchers.get(name)!;

    let pkgJsonOnlyTrigger = false;
    for (const file of changedFiles) {
      let relToPackage: string;
      if (isRoot) {
        relToPackage = file;
      } else {
        if (!file.startsWith(prefix)) continue;
        relToPackage = file.slice(prefix.length);
      }
      if (!matcher(relToPackage)) continue;
      if (relToPackage === 'package.json') {
        pkgJsonOnlyTrigger = true; // defer — refine by inspecting which fields changed
      } else {
        changed.add(name); // any other matched file is a definite change
        break;
      }
    }

    // package.json was the only thing that matched — only flag if a publish-affecting
    // field actually changed (a dev-only dependency bump shouldn't require a release).
    if (!changed.has(name) && pkgJsonOnlyTrigger) {
      baseRef ??= getBaseCompareRef(rootDir, config.baseBranch);
      if (
        await packageJsonAffectsRelease(rootDir, baseRef, pkgRelDir, ignoredFields, pkg.bumpy?.releaseTriggeringDevDeps)
      ) {
        changed.add(name);
      }
    }
  }