Bun's bundler (and esbuild) cannot tree-shake `export * as X from "./mod"`
barrels — see evanw/esbuild#1420. Rollup can, using AST-level analysis to
drop unused exports and their transitive imports.
This adds a Rollup pre-pass to the build pipeline that runs before Bun's
compile step. Rollup resolves internal source, eliminates dead code across
the 57 `export * as` barrels, and writes tree-shaken ESM to a temp directory.
Bun then compiles the pre-processed output into the final binary.
- Add `script/treeshake-prepass.ts` with Bun.Transpiler-based Rollup plugin
- Integrate into `script/build.ts` (skippable via `--skip-treeshake`)
- Add `rollup` as devDependency
- Pre-pass completes in ~5s, negligible vs full multi-platform build
Current bundle savings are modest (~0.7%) because the single-entrypoint
architecture means most code paths are reachable. Savings scale with:
- Per-command entry points or lazy loading
- Remaining 50 `export namespace` → `export * as` migrations
- Future code splitting
https://claude.ai/code/session_01R7zMpXjsq1R6uR7xpyJ14i
Claude
d1a9ef8053