feat(rust): introduce `rolldown_watcher` by hyf0 · Pull Request #8161 · rolldown/rolldown

hyf0 · 2026-02-01T21:40:25Z

For each event, rollup will wait for its all listeners's finish. This PR uses trait-based design for dispatching events to stimulate similar behaviors.
Most of design is inspired from dev engine. I keep them separated instead of merging them together, because DevEngine is too complicated to be used for watch scenario.
Might have some bad smells. Will improve it in later PRs.

hyf0 · 2026-02-01T21:40:44Z

feat(node/watch): implement TypeScript API for new watch mode #8239
feat(rust): introduce rolldown_watcher #8161 👈 (View in Graphite)
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crates/rolldown_watcher/src/watch_task.rs

github-actions · 2026-02-08T15:45:01Z

Benchmarks Rust

target: main(c81f0af)
pr: 02-02-feat_rust_introduce_rolldown_watcher_(ac45759)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.05     74.7±3.14ms        ? ?/sec    1.00     70.9±2.04ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.03     80.0±2.44ms        ? ?/sec    1.00     77.7±2.22ms        ? ?/sec
bundle/bundle@rome_ts                                        1.00    103.9±2.91ms        ? ?/sec    1.01    105.4±3.03ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.00    115.3±2.14ms        ? ?/sec    1.00    115.2±2.31ms        ? ?/sec
bundle/bundle@threejs                                        1.00     36.9±1.38ms        ? ?/sec    1.00     36.9±1.13ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.00     41.5±1.05ms        ? ?/sec    1.00     41.6±1.50ms        ? ?/sec
bundle/bundle@threejs10x                                     1.00    377.6±6.61ms        ? ?/sec    1.00    376.2±6.88ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.00    433.0±5.59ms        ? ?/sec    1.01   436.3±10.01ms        ? ?/sec
scan/scan@rome_ts                                            1.00     80.5±1.81ms        ? ?/sec    1.03     82.6±1.93ms        ? ?/sec
scan/scan@threejs                                            1.00     27.7±0.51ms        ? ?/sec    1.02     28.1±0.51ms        ? ?/sec
scan/scan@threejs10x                                         1.00    286.2±5.67ms        ? ?/sec    1.02    292.4±5.78ms        ? ?/sec

Copilot

Pull request overview

Introduces a new Rust crate rolldown_watcher implementing a watch-mode event loop with debouncing and trait-based event dispatch, plus a new example showcasing the API.

Changes:

Add rolldown_watcher crate (watcher + coordinator + per-task bundler integration + state machine).
Add a watch_new example in rolldown demonstrating watcher usage.
Expose a couple of experimental Bundler wrapper APIs to support watch/incremental workflows.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
crates/rolldown_watcher/src/watcher.rs	Public Watcher API, config mapping, and task/coordinator startup/shutdown wiring
crates/rolldown_watcher/src/watch_task.rs	Per-config watch task: bundler ownership, watched-file tracking, rebuild logic, plugin hooks
crates/rolldown_watcher/src/watch_coordinator.rs	Coordinator actor: debounce state machine integration and Rollup-like rebuild sequencing
crates/rolldown_watcher/src/state.rs	Watcher debounce/close state machine and change de-duplication
crates/rolldown_watcher/src/msg.rs	Internal messages between fs watchers and coordinator
crates/rolldown_watcher/src/lib.rs	Module wiring + public re-exports
crates/rolldown_watcher/src/handler.rs	Async event handler trait for watch lifecycle/change events
crates/rolldown_watcher/src/event.rs	Watch event types and event payload structs
crates/rolldown_watcher/Cargo.toml	New crate manifest + dependencies
crates/rolldown/src/bundler/impl_bundler_incremental_build.rs	Add experimental public wrapper for cached-bundle helper
crates/rolldown/src/bundler/bundler.rs	Add experimental public wrapper for resetting closed flag in watch mode
crates/rolldown/examples/watch_new.rs	New example using `rolldown_watcher`
crates/rolldown/Cargo.toml	Add `rolldown_watcher` dev-dependency for examples
Cargo.lock	Lockfile updates for new crate/deps

crates/rolldown_watcher/src/event.rs

crates/rolldown_watcher/src/watch_task.rs

crates/rolldown_watcher/src/watcher.rs

crates/rolldown_watcher/src/watch_coordinator.rs

hyf0 · 2026-02-09T12:56:00Z

Merge activity

Feb 9, 12:56 PM UTC: The merge label 'graphite: merge-when-ready' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Feb 9, 12:56 PM UTC: hyf0 added this pull request to the Graphite merge queue.
Feb 9, 1:06 PM UTC: Merged by the Graphite merge queue.

- For each event, rollup will wait for its all listeners's finish. This PR uses trait-based design for dispatching events to stimulate similar behaviors. - Most of design is inspired from dev engine. I keep them separated instead of merging them together, because `DevEngine` is too complicated to be used for watch scenario. - Might have some bad smells. Will improve it in later PRs.

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@sapphi-red

## [1.0.0-rc.4] - 2026-02-11 💡 Granular `comments` Option - New `output.comments` option provides fine-grained control over comment preservation - The `output.legalComments` option is now deprecated and use `comments.legal` instead ### 🚀 Features - rename error name to `RolldownError` from `RollupError` (#8262) by @sapphi-red - add hidden `resolve_tsconfig` function for Vite (#8257) by @sapphi-red - rust: introduce `rolldown_watcher` (#8161) by @hyf0 - unify `comments` and `legalComments` into a single granular `comments` option (#8229) by @IWANABETHATGUY - add builtin plugin for visualizing chunk graph (#8162) by @IWANABETHATGUY - show import declaration location in AssignToImport errors (#8222) by @Copilot - show import declaration span in CannotCallNamespace error (#8223) by @Copilot - emit error when plugin accidentally removes runtime module symbols (#8203) by @IWANABETHATGUY - support tsconfig loading & inputMap for `transform` (#8180) by @sapphi-red - rolldown_plugin_vite_reporter: update warning message to link to Rolldown docs (#8205) by @sapphi-red ### 🐛 Bug Fixes - avoid panic on untranspiled JSX syntax by reporting a diagnostic error (#8226) by @IWANABETHATGUY - rolldown_plugin_vite_import_glob: relax absolute path check and improve invalid glob warning (#8219) by @shulaoda - merge chunks after detect circular reference (#8154) by @IWANABETHATGUY - rust: detect runtime module side effects based on its content (#8209) by @hyf0 ### 🚜 Refactor - rename `other` to `jsdoc` in comments options (#8256) by @IWANABETHATGUY - rename chunk-visualize plugin with bundle-analyzer plugin (#8255) by @IWANABETHATGUY - remove EXPORT_UNDEFINED_VARIABLE error (#8228) by @Copilot - consolidate missing runtime symbol errors into a single diagnostic (#8220) by @IWANABETHATGUY - stabilize `parse` and `parseSync` (#8215) by @sapphi-red - return errors instead of panicking on builtin plugin conversion failure (#8217) by @shulaoda - expose `parse` / `minify` / `transform` from `rolldown/utils` (#8214) by @sapphi-red - prepare defer chunk merging (#8153) by @IWANABETHATGUY ### 📚 Documentation - remove `<script>` escape behavior difference note from `platform` option (#8253) by @sapphi-red - TypeScript & JSX support by plugins (#8183) by @sapphi-red ### 🧪 Testing - ensure runtime module is preserved even if it's not used but has side effects (#8213) by @hyf0 ### ⚙️ Miscellaneous Tasks - deps: update oxc to v0.113.0 (#8267) by @renovate[bot] - deps: update dependency oxlint-tsgolint to v0.12.0 (#8272) by @renovate[bot] - deps: update oxc apps (#8269) by @renovate[bot] - deps: update test262 submodule for tests (#8261) by @sapphi-red - deps: update crate-ci/typos action to v1.43.4 (#8260) by @renovate[bot] - deps: update dependency esbuild to v0.27.3 (#8250) by @renovate[bot] - deps: update rust crates (#8244) by @renovate[bot] - deps: update dependency semver to v7.7.4 (#8247) by @renovate[bot] - deps: update github-actions (#8243) by @renovate[bot] - deps: update npm packages (#8245) by @renovate[bot] - deps: update oxc resolver to v11.17.1 (#8240) by @renovate[bot] - deps: update rust crate oxc_sourcemap to v6.0.2 (#8241) by @renovate[bot] - rust: handle ignored `RUSTSEC-2025-0141` cargo check error (#8235) by @hyf0 - deps: update dependency oxlint-tsgolint to v0.11.5 (#8233) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to ^0.22.0 (#8232) by @renovate[bot] - deps: update crate-ci/typos action to v1.43.3 (#8225) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.21.9 (#8224) by @renovate[bot] - deps: update crate-ci/typos action to v1.43.2 (#8212) by @renovate[bot] - remove rolldown_plugin_vite_wasm_helper (#8207) by @shulaoda - build docs for production (#8206) by @sapphi-red Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>

github-actions bot assigned hyf0 Feb 1, 2026

hyf0 force-pushed the 02-02-feat_rust_introduce_rolldown_watcher_ branch from 189e993 to e559fae Compare February 8, 2026 15:29

hyf0 mentioned this pull request Feb 8, 2026

feat(node/watch): implement TypeScript API for new watch mode #8239

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hyf0 marked this pull request as ready for review February 8, 2026 15:29

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hyf0 force-pushed the 02-02-feat_rust_introduce_rolldown_watcher_ branch from e559fae to 4bcdafc Compare February 8, 2026 15:56

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hyf0 force-pushed the 02-02-feat_rust_introduce_rolldown_watcher_ branch from 4bcdafc to ac45759 Compare February 9, 2026 02:24

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graphite-app bot merged commit 9a5231f into main Feb 9, 2026
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This was referenced Feb 11, 2026

release: v1.0.0-rc.4 #8271

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feat(rust): introduce `rolldown_watcher`#8161

feat(rust): introduce `rolldown_watcher`#8161
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