rolldown/rolldown

The user-facing product is chiefly a CLI and a programmatic bundling API. Output operations support memory generation and filesystem writing, complemented by plugins and compiler utilities. Experimental surfaces expose development-engine callbacks, browser memory filesystems, and Vite-oriented integrations. The following catalog covers inspected capabilities rather than asserting an exhaustive option inventory.

• rolldown(input) returns a Rollup-compatible bundle object whose generate() produces in-memory output and write() produces disk output.
  packages/rolldown/src/api/rolldown/index.ts#L6-12packages/rolldown/src/api/rolldown/rolldown-build.ts#L45-69
• The experimental build() convenience API defaults write to true, supports write:false, accepts arrays, and closes each individual build in finally.
  packages/rolldown/src/api/build.ts#L12-19packages/rolldown/src/api/build.ts#L55-71
• The CLI handles help/version, config-based or positional-input bundling, and --environment assignments; without an output destination it prints generated code/assets, while watch requires an output destination.
  packages/rolldown/src/cli/index.ts#L17-54packages/rolldown/src/cli/commands/bundle.ts#L46-75
• Configuration discovery supports rolldown.config with .js/.mjs/.cjs/.ts/.mts/.cts extensions; config functions receive raw CLI arguments, and native versus bundle loaders select execution paths.
  packages/rolldown/src/utils/load-config.ts#L62-74packages/rolldown/src/utils/load-config.ts#L165-185packages/rolldown/src/cli/commands/bundle.ts#L25-42
• watch() rebuilds when modules change and exposes event/change/restart/close notifications; BUNDLE_END and ERROR events carry results with close support.
  packages/rolldown/src/api/watch/index.ts#L9-16packages/rolldown/src/api/watch/watcher.ts#L19-59
• Experimental DevEngine exposes a current module graph, HMR/output/additional-asset callbacks, rebuild strategy selection, and configurable polling/debounce/include/exclude watch settings.
  packages/rolldown/src/api/dev/dev-engine.ts#L34-58packages/rolldown/src/api/dev/dev-engine.ts#L76-134
• rolldown/utils exports synchronous/asynchronous parsing, minification, and transformation plus TsconfigCache and Visitor; experimental browser builds additionally expose memfs.
  packages/rolldown/src/utils-index.ts#L1-13packages/rolldown/src/experimental-index.ts#L58-88
• Inspected builtins cover external-require conversion and replacement, plus experimental Vite resolve/JSON/glob/import-analysis/preload/worker/React-refresh/reporting/manifest/transform helpers and bundle analysis.
  packages/rolldown/src/plugins-index.ts#L1-2packages/rolldown/src/experimental-index.ts#L24-54