fix(webpack): allow emitting assets from buildEnd by Huzaifa-Asif · Pull Request #619 · unjs/unplugin

Huzaifa-Asif · 2026-10-03T16:27:29Z

Summary

run webpack 5+ buildEnd hooks during processAssets at the additional-assets stage
keep the existing emit-hook behavior as a compatibility fallback for older webpack versions
add an integration regression that checks buildEnd runs before webpack begins emitting and that this.emitFile writes the requested asset

Webpack currently invokes buildEnd from compiler.hooks.emit, after compilation assets have been sealed. Calling this.emitFile there triggers webpack's DEP_WEBPACK_COMPILATION_ASSETS warning and is incompatible with webpack's asset lifecycle. Moving the hook into processAssets lets emitted assets participate in the rest of webpack's asset pipeline.

Resolves #473.

Verification

pnpm exec vitest run test/unit-tests/build-end/build-end.test.ts — 1 passed (the regression fails on main because buildEnd runs after emit begins)
pnpm test — 24 files passed, 3 skipped; 167 tests passed, 25 skipped
pnpm lint
pnpm typecheck
pnpm build
git diff --check

AI assistance

OpenAI Codex assisted with issue research, implementation, tests, verification, and drafting this description. The contributor reviewed the submitted code and tests on 2026-10-04, after the draft PR had been opened.

coderabbitai · 2026-10-03T16:27:37Z

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults
Review profile: CHILL
Plan: Advanced
Run ID: 815e387e-3319-495f-acb7-ca0c60c10428

📥 Commits

Reviewing files that changed from the base of the PR and between f2acf00 and 9a619b1.

📒 Files selected for processing (3)

src/webpack/index.ts
test/unit-tests/build-end/.gitignore
test/unit-tests/build-end/build-end.test.ts

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📝 Walkthrough

Walkthrough

Webpack runs buildEnd during processAssets at PROCESS_ASSETS_STAGE_ADDITIONAL when that stage is available. Otherwise, it uses the emit hook. An integration test checks hook order and verifies that an asset created by buildEnd reaches the output directory.

Changes

Webpack buildEnd asset emission

Layer / File(s)	Summary
Schedule buildEnd and verify asset output `src/webpack/index.ts`, `test/unit-tests/build-end/build-end.test.ts`, `test/unit-tests/build-end/.gitignore`	When Webpack exposes `PROCESS_ASSETS_STAGE_ADDITIONAL`, `buildEnd` runs during `processAssets`; otherwise, the `emit` fallback remains. The integration test checks that `buildEnd` runs before `emit` and that its emitted JSON asset is written to the output directory. The test output directory is ignored.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Low

Sequence Diagram(s)

sequenceDiagram
  participant WebpackCompiler
  participant Compilation
  participant UnpluginBuildEnd
  participant Output
  WebpackCompiler->>Compilation: Start thisCompilation
  Compilation->>UnpluginBuildEnd: Run buildEnd at PROCESS_ASSETS_STAGE_ADDITIONAL
  UnpluginBuildEnd->>Compilation: Emit build-end.json
  WebpackCompiler->>Output: Write emitted asset

Merge Risk: ⚪ Minimal · up to 9a619

No actionable merge-blocking risk remains for the Webpack buildEnd change after normal checks.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 9a619

The change preserves existing plugin authority and keeps asset emission under Webpack’s control. Successful execution is covered by a regression test, but failure after asset creation and repeated or interrupted builds remain unverified.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

inferred — The evidenced exposure is the active Webpack compilation and its downstream asset output for builds using the configured plugin. The timing change does not establish new tenant, service, credential, or environment authority.

Trust Boundaries and Controls

observed — Asset filenames and contents originate from the configured plugin. The existing context requires a compilation and delegates emission to compilation.emitAsset; it does not itself validate filenames as a security boundary. The changed scheduling continues to use that same context and sink.

Resilience and Maintainability Implications

inferred — Exclusive registration and compilation-local closures support isolation at the adapter level. They do not establish terminal output suppression or cleanup after a hook emits an asset and then rejects; those guarantees depend on Webpack lifecycle behavior not resolved by the supplied regression.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Issue `#473` asks for webpack `buildEnd` to support `this.emitFile`. The PR summary states that webpack runs `buildEnd` from `thisCompilation` at `PROCESS_ASSETS_STAGE_ADDITIONAL` when available, with t…
Out of Scope Changes check	✅ Passed	The reported changes are limited to the webpack `buildEnd` lifecycle fix, its integration regression test, and a `.gitignore` entry for that test's output. These changes support issue `#473`. The whole-…
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: enabling asset emission from webpack’s buildEnd hook.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 unsupported.)

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fix(webpack): allow emitting assets from buildEnd

9a619b1

Huzaifa-Asif marked this pull request as ready for review October 4, 2026 06:35

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fix(webpack): allow emitting assets from buildEnd - #619

fix(webpack): allow emitting assets from buildEnd#619
Huzaifa-Asif wants to merge 1 commit into
unjs:mainfrom
Huzaifa-Asif:fix/webpack-build-end-emit-file

Huzaifa-Asif commented Oct 3, 2026 •

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Huzaifa-Asif commented Oct 3, 2026 •

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