feat: support compile main-thread script to bytecode in external bundle by upupming · Pull Request #2459 · lynx-family/lynx-stack

upupming · 2026-04-14T08:42:09Z

Summary by CodeRabbit

New Features
- External bundles can now compile main-thread scripts to bytecode, improving startup performance and protection for main-thread code.
- Configuration now accepts an option to target specific main-thread chunks for bytecode encoding.
Tests
- Expanded tests to validate bytecode encoding and custom-section structure for main-thread bundle outputs.

Checklist

Tests updated (or not required).
Documentation updated (or not required).
Changeset added, and when a BREAKING CHANGE occurs, it needs to be clearly marked (or not required).

chatgpt-codex-connector · 2026-04-14T08:42:15Z

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changeset-bot · 2026-04-14T08:42:18Z

🦋 Changeset detected

Latest commit: 5ce3b26

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@lynx-js/lynx-bundle-rslib-config	Patch
@lynx-js/react-umd	Patch
@lynx-js/react	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

coderabbitai · 2026-04-14T08:42:28Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 522316f7-629d-431a-92a2-bf9f87e8f84e

📥 Commits

Reviewing files that changed from the base of the PR and between 25f19ff and 5ce3b26.

📒 Files selected for processing (1)

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts

✅ Files skipped from review due to trivial changes (1)

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts

📝 Walkthrough

Walkthrough

Added support for compiling main-thread scripts to bytecode in external bundles: introduced a mainThreadChunks option, merged plugin wiring into a single external-bundle plugin that collects main-thread chunk names, updated encoding to mark matching JS assets as JsBytecode, and expanded tests to assert custom-section structures.

Changes

Cohort / File(s)	Summary
Changeset & API `.changeset/flat-bikes-boil.md`, `packages/rspeedy/lynx-bundle-rslib-config/etc/lynx-bundle-rslib-config.api.md`	Added changeset; API report updated to include optional `mainThreadChunks?: string[]` on `ExternalBundleWebpackPluginOptions`.
Bundler wiring `packages/rspeedy/lynx-bundle-rslib-config/src/externalBundleRslibConfig.ts`	Merged prior plugins into one `lynx:external-bundle` plugin, changed signature to accept `{ engineVersion }`, collected main-thread entry names (`entryName + '.js'`) and pass `mainThreadChunks` to the webpack plugin; made `api.modifyBundlerChain` callback async.
Webpack plugin `packages/rspeedy/lynx-bundle-rslib-config/src/webpack/ExternalBundleWebpackPlugin.ts`	Added `mainThreadChunks?: string[]` option; encode path adds `customSections` entry attribute `'encoding': 'JsBytecode'` for assets matching `mainThreadChunks`; `encode` now receives `useLepusNG: true`.
Tests `packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts`	Strengthened assertions on `decodedResult['custom-sections']`: verify array/string shapes and numeric markers for `index:CSS`, `index`, and `index__main-thread` entries indicating expected bytecode sections.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

fix(react-webpack-plugin): fix sourcemap misalignment in lazy bundles #2361: Uses mainThreadChunks for asset wrapping/BannerPlugin behavior that interacts with this PR's main-thread targeting.
feat: support bundle and load css in external bundle #2143: Touches ExternalBundleWebpackPlugin encoding and test surface; likely overlaps in encoding/custom-section behavior.
feat: init @lynx-js/lynx-bundle-rslib-config #1943: Prior refactor of the same external-bundle plugin files; changes the same wiring and tests.

Suggested reviewers

colinaaa
luhc228

Poem

🐰 Hop-hop, I scurry through the build,
I count main-thread chunks and keep them thrilled,
I whisper "JsBytecode" in each matched file,
Bundles sleep light and wake with a smile. ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: adding support for compiling main-thread scripts to bytecode in external bundles, which is the primary objective reflected across all modified files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Create PR with unit tests
Commit unit tests in branch feat/external-bundle-mts-bytecode

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codecov · 2026-04-14T08:46:02Z

❌ 10 Tests Failed:

Tests completed	Failed	Passed	Skipped
4784	10	4774	98

View the full list of 10 ❄️ flaky test(s)

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > NODE_ENV configuration > should output different artifacts for development and production NODE_ENV

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 2.15s run time

AssertionError: expected undefined not to be undefined // Object.is equality
 ❯ test/external-bundle.test.ts:335:31

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > mount externals library > should apply reactlynx externals preset to the final bundle

Flake rate in main: 9.09% (Passed 40 times, Failed 4 times)

Stack Traces | 0.373s run time

AssertionError: expected [ 'utils' ] to deeply equal [ 'utils', 'utils__main-thread' ]

- Expected
+ Received

  [
    "utils",
-   "utils__main-thread",
  ]

 ❯ test/external-bundle.test.ts:474:66

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > mount externals library > should let explicit externals override the reactlynx preset

Flake rate in main: 9.09% (Passed 40 times, Failed 4 times)

Stack Traces | 0.365s run time

AssertionError: the given combination of arguments (undefined and string) is invalid for this assertion. You can use an array, a map, an object, a set, a string, or a weakset instead of a string
 ❯ test/external-bundle.test.ts:521:68

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > mount externals library > should mount externals library to globalThis

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 0.434s run time

AssertionError: expected [ 'utils' ] to deeply equal [ 'utils', 'utils__main-thread' ]

- Expected
+ Received

  [
    "utils",
-   "utils__main-thread",
  ]

 ❯ test/external-bundle.test.ts:646:66

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > mount externals library > should mount externals library to lynx by default

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 0.329s run time

AssertionError: expected [ 'utils' ] to deeply equal [ 'utils', 'utils__main-thread' ]

- Expected
+ Received

  [
    "utils",
-   "utils__main-thread",
  ]

 ❯ test/external-bundle.test.ts:420:66

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > pluginReactLynx > should handle macros

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 0.000736s run time

AssertionError: expected [ 'utils' ] to deeply equal [ 'utils', 'utils__main-thread' ]

- Expected
+ Received

  [
    "utils",
-   "utils__main-thread",
  ]

 ❯ test/external-bundle.test.ts:741:66

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > should build external bundle > should build both main-thread and background code into external bundle

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 1.81s run time

AssertionError: expected [ 'utils' ] to deeply equal [ 'utils', 'utils__main-thread' ]

- Expected
+ Received

  [
    "utils",
-   "utils__main-thread",
  ]

 ❯ test/external-bundle.test.ts:123:66

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > should build external bundle > should build css into external bundle

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 0.451s run time

AssertionError: expected [ 'index', 'index:CSS' ] to deeply equal [ 'index', 'index:CSS', …(1) ]

- Expected
+ Received

  [
    "index",
    "index:CSS",
-   "index__main-thread",
  ]

 ❯ test/external-bundle.test.ts:241:66

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > should build external bundle > should include LoadingConsumerModulesRuntimeModule in the main-thread bundle

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 1.55s run time

AssertionError: the given combination of arguments (undefined and string) is invalid for this assertion. You can use an array, a map, an object, a set, a string, or a weakset instead of a string
 ❯ test/external-bundle.test.ts:289:68

packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts > should build external bundle > should only build main-thread code into external bundle

Flake rate in main: 8.33% (Passed 99 times, Failed 9 times)

Stack Traces | 0.71s run time

AssertionError: expected [] to deeply equal [ 'utils' ]

- Expected
+ Received

- [
-   "utils",
- ]
+ []

 ❯ test/external-bundle.test.ts:153:59

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coderabbitai

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In
`@packages/rspeedy/lynx-bundle-rslib-config/src/webpack/ExternalBundleWebpackPlugin.ts`:
- Around line 138-142: The check in ExternalBundleWebpackPlugin that uses
this.options.mainThreadChunks?.includes(cur.name) compares against the emitted
asset filename (cur.name) which can include hashes/dirs; change it to compare
normalized chunk/section identity: derive a stable name (e.g., use
cur.chunk?.name or extract a basename/normalized section name from cur.name) and
compare that against a normalized version of this.options.mainThreadChunks (map
the configured names through the same normalization). Update the condition to
use the normalizedChunkName (instead of cur.name) so the JsBytecode branch is
chosen by chunk identity, not the raw emitted filename.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 4c307d79-ebf4-4bb5-932b-8792c7227ca4

📥 Commits

Reviewing files that changed from the base of the PR and between 7332eb4 and 25f19ff.

📒 Files selected for processing (5)

.changeset/flat-bikes-boil.md
packages/rspeedy/lynx-bundle-rslib-config/etc/lynx-bundle-rslib-config.api.md
packages/rspeedy/lynx-bundle-rslib-config/src/externalBundleRslibConfig.ts
packages/rspeedy/lynx-bundle-rslib-config/src/webpack/ExternalBundleWebpackPlugin.ts
packages/rspeedy/lynx-bundle-rslib-config/test/external-bundle.test.ts

coderabbitai · 2026-04-14T08:48:46Z

+                  ...(this.options.mainThreadChunks?.includes(cur.name)
+                    ? {
+                      'encoding': 'JsBytecode',
+                    }
+                    : {}),


⚠️ Potential issue | 🟠 Major

Match main-thread assets by chunk identity, not exact emitted filename.

mainThreadChunks?.includes(cur.name) only works when the emitted asset name is exactly the stored value. As soon as a caller uses a subdirectory or hash in the JS filename template, this branch stops tagging the main-thread section as JsBytecode and silently falls back to plain JS. Compare against a normalized section/chunk name instead of the raw emitted filename.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed. In `@packages/rspeedy/lynx-bundle-rslib-config/src/webpack/ExternalBundleWebpackPlugin.ts` around lines 138 - 142, The check in ExternalBundleWebpackPlugin that uses this.options.mainThreadChunks?.includes(cur.name) compares against the emitted asset filename (cur.name) which can include hashes/dirs; change it to compare normalized chunk/section identity: derive a stable name (e.g., use cur.chunk?.name or extract a basename/normalized section name from cur.name) and compare that against a normalized version of this.options.mainThreadChunks (map the configured names through the same normalization). Update the condition to use the normalizedChunkName (instead of cur.name) so the JsBytecode branch is chosen by chunk identity, not the raw emitted filename.

codspeed-hq · 2026-04-14T08:58:08Z

Merging this PR will improve performance by 11.24%

⚡ 1 improved benchmark
✅ 80 untouched benchmarks
⏩ 26 skipped benchmarks¹

Performance Changes

	Benchmark	`BASE`	`HEAD`	Efficiency
⚡	`transform 1000 view elements`	45.4 ms	40.8 ms	+11.24%

_{Comparing feat/external-bundle-mts-bytecode (5ce3b26) with main (95c2dc3)}

26 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

relativeci · 2026-04-14T08:59:25Z

React Example

#7383 Bundle Size — 223.33KiB (0%).

5ce3b26(current) vs 95c2dc3 main#7382(baseline)

Bundle metrics no changes

	Current #7383	Baseline #7382
Initial JS	`0B`	`0B`
Initial CSS	`0B`	`0B`
Cache Invalidation	`0%`	`0%`
Chunks	`0`	`0`
Assets	`4`	`4`
Modules	`179`	`179`
Duplicate Modules	`69`	`69`
Duplicate Code	`44.48%`	`44.48%`
Packages	`2`	`2`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #7383	Baseline #7382
IMG	`145.76KiB`	`145.76KiB`
Other	`77.58KiB`	`77.58KiB`

Bundle analysis report Branch feat/external-bundle-mts-bytecod... Project dashboard

^{Generated by RelativeCI Documentation Report issue}

relativeci · 2026-04-14T08:59:26Z

Web Explorer

#8957 Bundle Size — 749.55KiB (0%).

5ce3b26(current) vs 95c2dc3 main#8956(baseline)

Bundle metrics

2 changes

	Current #8957	Baseline #8956
Initial JS	`44.45KiB`	`44.45KiB`
Initial CSS	`2.16KiB`	`2.16KiB`
Cache Invalidation	`0%`	`0%`
Chunks	`8`	`8`
Assets	`10`	`10`
Modules	`148`(`-0.67%`)	`149`
Duplicate Modules	`11`	`11`
Duplicate Code	`34.99%`(`+0.03%`)	`34.98%`
Packages	`3`	`3`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #8957	Baseline #8956
Other	`401.63KiB`	`401.63KiB`
JS	`345.76KiB`	`345.76KiB`
CSS	`2.16KiB`	`2.16KiB`

Bundle analysis report Branch feat/external-bundle-mts-bytecod... Project dashboard

^{Generated by RelativeCI Documentation Report issue}

relativeci · 2026-04-14T08:59:27Z

React External

#500 Bundle Size — 670.93KiB (+15.61%).

5ce3b26(current) vs 95c2dc3 main#499(baseline)

Bundle metrics

1 change

	Current #500	Baseline #499
Initial JS	`0B`	`0B`
Initial CSS	`0B`	`0B`
Cache Invalidation	`98.34%`	`0%`
Chunks	`0`	`0`
Assets	`3`	`3`
Modules	`17`	`17`
Duplicate Modules	`5`	`5`
Duplicate Code	`8.59%`	`8.59%`
Packages	`0`	`0`
Duplicate Packages	`0`	`0`

Bundle size by type

1 change

1 regression

	Current #500	Baseline #499
Other	`670.93KiB` (`+15.61%`)	`580.35KiB`

Bundle analysis report Branch feat/external-bundle-mts-bytecod... Project dashboard

^{Generated by RelativeCI Documentation Report issue}

relativeci · 2026-04-14T08:59:28Z

React MTF Example

#516 Bundle Size — 193.94KiB (0%).

5ce3b26(current) vs 95c2dc3 main#515(baseline)

Bundle metrics no changes

	Current #516	Baseline #515
Initial JS	`0B`	`0B`
Initial CSS	`0B`	`0B`
Cache Invalidation	`0%`	`0%`
Chunks	`0`	`0`
Assets	`3`	`3`
Modules	`173`	`173`
Duplicate Modules	`66`	`66`
Duplicate Code	`43.94%`	`43.94%`
Packages	`2`	`2`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #516	Baseline #515
IMG	`111.23KiB`	`111.23KiB`
Other	`82.71KiB`	`82.71KiB`

Bundle analysis report Branch feat/external-bundle-mts-bytecod... Project dashboard

^{Generated by RelativeCI Documentation Report issue}

feat: support compile main-thread script to bytecode in external bundle

25f19ff

upupming requested review from colinaaa and luhc228 as code owners April 14, 2026 08:42

coderabbitai bot reviewed Apr 14, 2026

View reviewed changes

Merge branch 'main' into feat/external-bundle-mts-bytecode

5ce3b26

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