Read packages/tools/bundle/README.md, then select one workflow:

Stable comparison: pnpm bundle-compare <base-ref>. Use HEAD~1 for the latest commit. Read tmp/bundle-stats.txt and report non-zero differences.
Selected comparison: pnpm bundle-compare-selected --base <ref> scratchpad/<fixture>.ts. Use only user-named or investigation-local fixtures; keep temporary fixtures out of the stable corpus.
Composition: pnpm bundle-analyze scratchpad/<fixture>.ts. Read raw data first and report the largest modules, dependency groups, and surprising inclusions. Its readable-name output is not an exact size measurement.
Current size: Build immediately before the direct bundle report so Effect packages resolve from current dist output.
Cleanup: Stable comparisons retain tmp/bundle-base for reuse unless cleanup is requested. Remove selected-comparison state retained with --keep-base after its final use. Verify cleanup without disturbing unrelated worktrees.

bundle-analysis