feat: load minimizers by module path in workers

[xiaoxiaojx]

Summary

• Allow minimizer.implementation as a module path string or { path, export } (sass-loader style). Default terser uses { path, export: "terserMinify" }.
• When every implementation in a task (including embedded) is a path, workers require via minify instead of serialize-javascript + new Function (transform). Inline minify functions keep the legacy path.
• Split helpers into implementation.js so the worker entry only exports minify / transform; unify loading through getMinimizerSlots / embeddedFromSlots.

Test plan

• yarn test (full suite)
• Confirm default parallel builds call worker.minify (not transform)
• Confirm minify: () => … / mixed path+function configs fall back to transform
• Smoke a yarn-linked webpack build / minimizer-handoff-unit bench against rebuilt dist

Made with Cursor

Summary by CodeRabbit

• New Features

  • Minimizer implementations can now be specified as module paths or { path, export } objects.
  • Supports default exports, named exports, and CommonJS module exports.
  • Path-based implementations run more efficiently in worker threads without function serialization.
  • Inline functions remain supported, including mixed configurations and embedded minimizers.

• Documentation

  • Updated configuration guidance and type definitions to describe module-based implementations and worker behavior.

[changeset-bot]

🦋 Changeset detected

Latest commit: 2575275

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

This PR includes changesets to release 1 package

Name	Type
minimizer-webpack-plugin	Minor

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[codecov]

Codecov Report

❌ Patch coverage is 99.10714% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 97.78%. Comparing base (1cf49b0) to head (2575275).

Files with missing lines	Patch %	Lines
src/implementation.js	98.27%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #732      +/-   ##
==========================================
+ Coverage   97.75%   97.78%   +0.02%     
==========================================
  Files           4        5       +1     
  Lines        1557     1623      +66     
  Branches      588      617      +29     
==========================================
+ Hits         1522     1587      +65     
- Misses         35       36       +1     

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[linux-foundation-easycla]

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: b9e823f5-fb06-4ef2-99cb-2f9663e51137

📥 Commits

Reviewing files that changed from the base of the PR and between 8cb5b9f and 2575275.

📒 Files selected for processing (5)

• README.md
• src/implementation.js
• src/index.js
• test/parallel-option.test.js
• types/index.d.ts

🚧 Files skipped from review as they are similar to previous changes (4)

• README.md
• src/implementation.js
• src/index.js
• types/index.d.ts

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---

Walkthrough

The plugin now accepts minimizer implementations as functions, module path strings, or { path, export } objects. Shared helpers normalize and load these implementations. The plugin stores configured values with loaded functions and uses worker.minify when all matched implementations and task values are module-path compatible. Tasks with inline functions continue to use transform. Schemas, type declarations, documentation, fixtures, and tests were updated.

Priority: ➖ Normal

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: loading minimizers by module path in workers.
Docstring Coverage	✅ Passed	Docstring coverage is 80.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 11 files. (1 skipped: 1…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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src/implementation.js

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[coderabbitai]

Actionable comments posted: 3

Caution

Some comments are outside the diff and can’t be posted inline due to GitHub limitations.

⚠️ Outside diff range comments (1)

🟠 Major · Pass the loaded minimizer function to declaredStage(). · index.js:1920

src/index.js:1920
🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Pass the loaded minimizer function to declaredStage(). A module path or { path, export } value does not expose the loaded function's getStage, so that minimizer uses defaultStage() instead of its declared stage. Use the corresponding loaded slot function while preserving the slot index for dispatch.

Proposed fix

   minimizersByStage(compiler) {
-    const { implementation } = this.options.minimizer;
-    const each = Array.isArray(implementation)
-      ? implementation
-      : [implementation];
+    const slots = this.getMinimizerSlots();
     const fallback = this.defaultStage(compiler);
     const byStage = new Map();

-    for (let i = 0; i < each.length; i++) {
-      const asked = declaredStage(compiler, each[i]);
+    for (let i = 0; i < slots.length; i++) {
+      const asked = declaredStage(compiler, slots[i].fn);

---

ℹ️ Review info

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Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 379b994c-fa58-470a-871e-7617fe8e2621

📥 Commits

Reviewing files that changed from the base of the PR and between 1cf49b0 and 8cb5b9f.

⛔ Files ignored due to path filters (2)

• test/__snapshots__/parallel-option.test.js.snap is excluded by !**/*.snap
• test/__snapshots__/validate-options.test.js.snap is excluded by !**/*.snap

📒 Files selected for processing (14)

• .changeset/worker-implementation-path.md
• README.md
• src/implementation.js
• src/index.js
• src/minify.js
• src/options.json
• test/extractComments-option.test.js
• test/fixtures/minify-default-export.js
• test/fixtures/minify-default-property.js
• test/implementation.test.js
• test/parallel-option.test.js
• types/implementation.d.ts
• types/index.d.ts
• types/minify.d.ts

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