Function loadCachedPlan

packages/bumpy/src/commands/publish.ts:693–725

* Try to load cached plan from `ci plan`. Returns the unpublished package names * if the cache is valid, or null to fall back to registry lookups. * * Validates that every cached package exists in the workspace with the same version, * so the cache can only filter — never fabricate — the set of

(rootDir: string, packages: Map<string, WorkspacePackage>)

 * so the cache can only filter — never fabricate — the set of packages.
 */
function loadCachedPlan(rootDir: string, packages: Map<string, WorkspacePackage>): Set<string> | null {
  const cachePath = `${rootDir}/${CI_PLAN_CACHE_PATH}`;
  let raw: string;
  try {
    raw = require('node:fs').readFileSync(cachePath, 'utf-8');
    // Clean up cache file after reading
    require('node:fs').unlinkSync(cachePath);
  } catch {
    return null;
  }

  try {
    const cached = JSON.parse(raw);
    if (cached?.mode !== 'publish' || !Array.isArray(cached.releases)) return null;

    const names = new Set<string>();
    for (const r of cached.releases) {
      if (typeof r.name !== 'string' || typeof r.newVersion !== 'string') return null;
      // Validate against workspace — reject if package doesn't exist or version doesn't match
      const pkg = packages.get(r.name);
      if (!pkg || pkg.version !== r.newVersion) {
        log.dim('  ci plan cache is stale — falling back to registry lookups');
        return null;
      }
      names.add(r.name);
    }

    log.dim('  Using cached plan from ci plan');
    return names;
  } catch {
    return null;
  }
}

/**
 * Find unpublished packages, using the ci plan cache if available.