feat: add dedupePeers option to reduce peer dependency duplication by zkochan · Pull Request #11071 · pnpm/pnpm

zkochan · 2026-03-23T16:26:19Z

Summary

Adds a new opt-in dedupePeers setting that reduces peer dependency duplication
Uses version-only peer identifiers (name@version) instead of full dep paths when building peer suffixes
Eliminates nested suffixes like (@emotion/react@11(react@18)) → (@emotion/react@11.0.0)
Transitive peers are still tracked (per-project isolation preserved), just identified by version instead of full dep path
Works correctly with autoInstallPeers

Before/After

Nested peer suffixes eliminated:

BEFORE: @emotion/styled@11(@emotion/react@11(react@18))(react@18)
AFTER:  @emotion/styled@11(@emotion/react@11.0.0)(react@18.0.0)

Multi-project correctness preserved:

project-1 (peer-c@1.0.0): abc-grand-parent@1.0.0(@pnpm.e2e/peer-c@1.0.0)
project-2 (peer-c@2.0.0): abc-grand-parent@1.0.0(@pnpm.e2e/peer-c@2.0.0)

Test plan

Unit tests: version-only suffixes, transitive peers with version-only IDs, multi-project isolation
Integration test: single project with transitive peer chain (abc-grand-parent)
Integration test: workspace with two projects using different peer-c versions
All existing tests pass (40/40 in deps-resolver, 67/67 in deps-installer peerDependencies)
All modified packages compile successfully

When enabled, this option applies two optimizations to peer dependency resolution: 1. Version-only peer suffixes: Uses name@version instead of full dep paths (including nested peer suffixes) when building peer identity hashes. This eliminates deeply nested suffixes like (foo@1.0.0(bar@2.0.0)). 2. Transitive peer pruning: Only directly declared peer dependencies are included in a package's suffix. Transitive peers from children are not propagated upward, preventing combinatorial explosion while maintaining correct node_modules layout. The option is scoped per-project: each workspace project defines a peer resolution environment, and all packages within that project's tree share that environment. Projects with different peer versions correctly produce different instances. Closes #11070

…r lockfile write The frozen install path (used by approve-builds) calls getOutdatedLockfileSetting but was missing the dedupePeers parameter. This caused a false LOCKFILE_CONFIG_MISMATCH error because the lockfile had the key written (as undefined/null via YAML serialization) while the check function received undefined for the config value. Fix: pass dedupePeers to the settings check call, and use spread syntax to only write the dedupePeers key to lockfile settings when it's truthy (avoiding undefined keys).

Write the value directly instead of spread syntax, and use the same != null guard pattern as autoInstallPeers in the settings checker.

When dedupePeers is false (default), don't write it to lockfile settings. This avoids adding a new key to every lockfile.

Instead of pruning transitive peers entirely (which prevented per-project differentiation), keep them but use version-only identifiers. This way: - Packages like abc-grand-parent still get a peer suffix when different projects provide different peer versions (correct per-project isolation) - But the suffixes use name@version instead of full dep paths, eliminating the nested parentheses that cause combinatorial explosion

Copilot

Pull request overview

This PR introduces an opt-in dedupePeers setting to reduce peer dependency duplication by changing how peer suffixes are computed (using version-only peer identifiers instead of full dep paths), and wires the option through the installer/resolver and lockfile settings.

Changes:

Added dedupePeers to config/workspace state, installer options, and lockfile settings so it can be persisted and checked for lockfile mismatch.
Updated peer resolution to build peer suffixes from version-only peer IDs (name@version) to avoid nested peer suffixes.
Added resolver + installer tests covering version-only suffixes and multi-project isolation behavior.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
workspace/state/src/types.ts	Adds `dedupePeers` to the persisted workspace-state settings key list.
lockfile/types/src/index.ts	Extends `LockfileSettings` with `dedupePeers`.
lockfile/settings-checker/src/getOutdatedLockfileSetting.ts	Adds lockfile-outdated detection for `settings.dedupePeers`.
installing/deps-resolver/src/resolvePeers.ts	Implements version-only peer IDs via `peerNodeIdToPeerId()` and passes `dedupePeers` through context.
installing/deps-resolver/src/index.ts	Plumbs `dedupePeers` into the resolver entrypoint options.
installing/deps-resolver/test/resolvePeers.ts	Adds unit tests for `dedupePeers` peer suffix behavior.
installing/deps-installer/src/install/extendInstallOptions.ts	Adds `dedupePeers` to strict install options and defaults it to `false`.
installing/deps-installer/src/install/index.ts	Persists `dedupePeers` into lockfile settings and includes it in outdated-setting checks; passes option into dependency resolution.
installing/deps-installer/src/getPeerDependencyIssues.ts	Adds `dedupePeers` to options typing for peer-issues collection.
installing/deps-installer/test/install/peerDependencies.ts	Adds integration tests asserting version-only suffixes in lockfile snapshots and workspace isolation.
installing/commands/src/recursive.ts	Allows recursive command options to include `dedupePeers`.
installing/commands/src/installDeps.ts	Allows installDeps command options to include `dedupePeers`.
installing/commands/src/install.ts	Allows install command options to include `dedupePeers`.
config/reader/src/Config.ts	Adds `dedupePeers?: boolean` to the `Config` interface.
.changeset/dedupe-peers-option.md	Documents the new `dedupePeers` feature for release notes.

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lajczi · 2026-03-23T22:59:23Z

Awesome work, Zoltan!

- Register dedupe-peers in config schema, types, and defaults so .npmrc/pnpm-workspace.yaml settings are parsed correctly - Use Boolean() comparison in settings checker so enabling dedupePeers on a pre-existing lockfile triggers re-resolution - Fix changeset text and test names: transitive peers are still propagated, just with version-only IDs (no nested dep paths)

When enabled, peer dependency suffixes use version-only identifiers (name@version) instead of full dep paths, eliminating nested suffixes like (foo@1.0.0(bar@2.0.0)). Transitive peers are still tracked but identified by version instead of full dep path. Backport of #11071 to v10. Closes #11070

GiladShoham · 2026-03-24T11:54:45Z

Amazing!
Will help our use case a lot :)

…11079) When enabled, peer dependency suffixes use version-only identifiers (name@version) instead of full dep paths, eliminating nested suffixes like (foo@1.0.0(bar@2.0.0)). Transitive peers are still tracked but identified by version instead of full dep path. Backport of #11071 to v10. Closes #11070

clemens · 2026-04-29T11:05:26Z

Am I overlooking something or isn't this included in the docs yet?

zkochan added 12 commits March 23, 2026 17:25

fix: write dedupePeers to lockfile like other settings

bf03bb9

Write the value directly instead of spread syntax, and use the same != null guard pattern as autoInstallPeers in the settings checker.

test: add integration test for dedupePeers in peerDependencies.ts

13c8bab

fix: only write dedupePeers to lockfile when enabled

5ee719c

When dedupePeers is false (default), don't write it to lockfile settings. This avoids adding a new key to every lockfile.

test: simplify dedupePeers test assertions

f682432

test: check exact snapshot keys in dedupePeers integration test

05ba0c9

test: add workspace test for dedupePeers with different peer versions

6dd57d3

refactor: extract peerNodeIdToPeerId helper in resolvePeers

909b452

refactor: simplify peerNodeIdToPeerId return

e4d1bda

fix: pin peer-a dist tag in dedupePeers tests for CI stability

65fb820

lajczi approved these changes Mar 23, 2026

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zkochan marked this pull request as ready for review March 23, 2026 22:49

Copilot AI review requested due to automatic review settings March 23, 2026 22:49

Copilot started reviewing on behalf of zkochan March 23, 2026 22:49 View session

Copilot AI reviewed Mar 23, 2026

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zkochan mentioned this pull request Mar 24, 2026

feat: add dedupePeers option to reduce peer dependency duplication #11079

Merged

3 tasks

zkochan merged commit 606f53e into main Mar 24, 2026
12 checks passed

zkochan deleted the dedupe-peers branch March 24, 2026 12:51

zkochan mentioned this pull request Mar 24, 2026

feat: dedupe peer dependencies teambit/bit#10249

Merged

btea mentioned this pull request Mar 27, 2026

Add dedupePeers to pnpm-workspace.json SchemaStore/schemastore#5504

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This was referenced Mar 30, 2026

Bump pnpm from 10.32.1 to 10.33.0 alveusgg/alveusgg#1955

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Bump pnpm from 10.32.1 to 10.33.0 alveusgg/extension#466

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feat: add dedupePeers option to reduce peer dependency duplication#11071

feat: add dedupePeers option to reduce peer dependency duplication#11071
zkochan merged 13 commits into
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zkochan commented Mar 23, 2026 •

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lajczi commented Mar 23, 2026

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zkochan commented Mar 23, 2026 •

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