Upgrade to Yarn v4

[marcins]

Motivation

Apart from slightly faster yarn install speeds, the main benefit for us to upgrading to Yarn v4 is that we can use workspace:* dependencies in package.json files, which simplifies dependency management (especially for "big" PRs when there's a release on the main branch to merge in).

Changes

• Upgrade the repo to use Yarn v4
• Fix various small issues

The bulk of the change is changing explicit versions of workspace dependencies in package.json to workspace:*.

Checklist

• Testing a dev release bump in AFM
• Existing or new tests cover this change
• There is a changeset for this change, or one is not required
• Added documentation for any new features to the docs/ folder

[no-changeset]: No functional changes

[changeset-bot]

⚠️ No Changeset found

Latest commit: 862af7d

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

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

[github-actions]

📊 Type Coverage Report

Coverage Comparison

Metric	Baseline	Current	Change
Coverage Percentage	92.29%	92.29%	➡️ 0.00%
Correctly Typed	223,459	223,516	+57
Total Expressions	242,120	242,173	+53
Untyped Expressions	18,661	18,657	-4

Files with Most Type Issues (Top 15)

File	Issues	Affected Lines
packages/core/integration-tests/test/javascript.ts	1152	745
packages/core/integration-tests/test/cache.ts	884	625
packages/core/integration-tests/test/scope-hoisting.ts	622	489
packages/utils/node-resolver-core/test/resolver.ts	476	177
packages/core/integration-tests/test/html.ts	468	294
packages/core/integration-tests/test/sourcemaps.ts	365	183
packages/core/test-utils/src/utils.ts	330	205
packages/core/integration-tests/test/incremental-bundling.ts	298	206
packages/core/core/src/dumpGraphToGraphViz.ts	251	108
packages/core/integration-tests/test/transpilation.ts	230	139
packages/core/integration-tests/test/output-formats.ts	227	161
packages/transformers/webextension/src/WebExtensionTransformer.ts	210	80
packages/core/core/src/requests/BundleGraphRequestRust.ts	195	68
packages/core/core/src/requests/AssetGraphRequestRust.ts	192	81
packages/core/integration-tests/test/css-modules.ts	191	107

---

This report was generated by the Type Coverage GitHub Action

[mattcompiles]

@marcins Have you validated that the changesets release handles this correctly?

[atlassian-cla-bot]

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The following users still need to sign our CLA:
❌marcins

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[github-actions]

📊 Benchmark Results

✅ No significant performance changes detected.

📊 Benchmark Results

Overall Performance

Test	Duration	JS Memory Peak	Native Memory Peak	vs Baseline	Status
Three.js Real Repository (JS)	16.00s	1.87GB	1.95GB	+1.08% duration, -10.33% JS memory	🟡 Neutral
Three.js Real Repository (V3)	20.00s	3.29GB	3.46GB	+1.24% duration, +4.30% JS memory	🟡 Neutral

🔍 Detailed Phase Analysis

Three.js Real Repository (JS)

Phase	Duration (avg)	Duration (p95)	Memory Peak (avg)	Memory Peak (p95)
resolving	7.58s	7.92s	1.30GB	1.47GB
transforming	7.57s	7.88s	1.30GB	1.47GB
bundling	7.38s	7.68s	1.30GB	1.47GB
bundled	7.01s	7.32s	1.42GB	1.58GB
packaging	4.73s	4.95s	1.52GB	1.68GB
optimizing	4.58s	4.76s	1.87GB	1.96GB

Three.js Real Repository (V3)

Phase	Duration (avg)	Duration (p95)	Memory Peak (avg)	Memory Peak (p95)
building	12.37s	15.90s	2.58GB	2.93GB
bundling	11.79s	15.35s	2.59GB	2.93GB
bundled	11.46s	15.03s	2.76GB	3.10GB
packaging	6.14s	6.47s	2.90GB	3.17GB
optimizing	5.93s	6.16s	3.29GB	3.52GB

💾 Unified Memory Analysis

Three.js Real Repository (JS) Memory Statistics

Memory Type	Metric	Min	Mean	Median	P95	P99	Max	Std Dev
JavaScript	RSS	1.26GB	1.67GB	1.62GB	1.96GB	1.96GB	1.96GB	228.19MB
	Heap Used	79.88MB	86.92MB	83.63MB	102.11MB	102.11MB	102.11MB	6.65MB
	Heap Total	97.35MB	134.21MB	129.35MB	188.16MB	188.16MB	188.16MB	27.05MB
	External	38.88MB	101.17MB	105.95MB	173.02MB	173.02MB	173.02MB	64.44MB
Native (Rust)	Physical Memory	1.40GB	1.59GB	1.59GB	1.83GB	1.93GB	1.95GB	146.60MB
	Virtual Memory	29.82GB	30.50GB	30.52GB	30.76GB	30.84GB	30.90GB	182.01MB

Sample Counts: JS: 14, Native: 252

Three.js Real Repository (V3) Memory Statistics

Memory Type	Metric	Min	Mean	Median	P95	P99	Max	Std Dev
JavaScript	RSS	2.37GB	3.04GB	3.02GB	3.52GB	3.52GB	3.52GB	367.83MB
	Heap Used	77.32MB	78.09MB	78.06MB	79.77MB	79.77MB	79.77MB	0.56MB
	Heap Total	89.70MB	98.18MB	94.70MB	123.45MB	123.45MB	123.45MB	10.14MB
	External	179.71MB	182.60MB	185.49MB	185.49MB	185.49MB	185.49MB	2.89MB
Native (Rust)	Physical Memory	2.84GB	3.12GB	3.15GB	3.33GB	3.46GB	3.46GB	140.54MB
	Virtual Memory	30.75GB	33.39GB	33.58GB	33.78GB	33.89GB	33.89GB	681.05MB

Sample Counts: JS: 14, Native: 248

🖥️ Environment

• Node.js: v22.17.0
• Platform: linux (x64)
• CPU: AMD EPYC 7763 64-Core Processor
• Total Memory: 15.62GB
• Git SHA: 862af7d
• Branch: mszczepanski/upgrade-to-yarn-v4
• Timestamp: 2026-03-24T02:44:07.747Z