install: keep the self-contained workspace setting out of the lockfile

[robobun]

Problem

• bun install --frozen-lockfile fails with error: lockfile had changes, but lockfile is frozen on a 1.4.0 lockfile when a workspace package.json has yarn's installConfig.hoistingLimits: "workspaces". 1.4.0 ignored that key. install: self-contained workspaces for the hoisted linker (workspaces.selfContained / installConfig.hoistingLimits) #40014 honors it.
• install: self-contained workspaces for the hoisted linker (workspaces.selfContained / installConfig.hoistingLimits) #40014 also put the setting into the lockfile. The hoist that writes the lockfile applied the barrier, bun.lock recorded "hoistingLimits", and the bun.lockb meta hash included the names. A 1.4.0 lockfile has none of that, so the frozen check sees a change.

Fix

• Keep the setting out of the lockfile, like other settings. Only the install hoist (Lockfile::filter) applies the barrier. The lockfile hoist (Lockfile::resolve) ignores it.
• bun.lock no longer writes or reads "hoistingLimits", and the meta hash matches 1.4.0 again. No release had either.
• Every install, a frozen one too, takes the set from the manifests. bun prune does too. It used the set from the lockfile.
• Verified: test/cli/install/bun-workspaces-self-contained.test.ts (12 new cases, the 10 lockfile cases fail on main). Also the 1.4.0 binary, both lockfile formats.

Background

• A self-contained workspace is a hoisting barrier: nothing it depends on goes above its node_modules. The yarn key and the root workspaces.selfContained list fill one set, Lockfile::self_contained_workspaces.
• Lockfile::resolve hoists the tree that the lockfile stores. The frozen check compares that tree (bun.lock) or the meta hash (bun.lockb) with the result after the manifest diff.
• Lockfile::filter hoists the tree that the installer lays out, with --filter and --production applied. bun prune removes what that tree does not hold.

Notes

Repro from the report (1.4.0 release binary, then a build of this branch):

mkdir -p r/packages/{app,lib} && cd r
echo '{"name":"r","private":true,"workspaces":["packages/*"]}' > package.json
echo '{"name":"lib","version":"1.0.0","dependencies":{"ms":"2.1.3"}}' > packages/lib/package.json
echo '{"name":"app","version":"1.0.0","installConfig":{"hoistingLimits":"workspaces"},"dependencies":{"lib":"workspace:*","ms":"2.0.0"}}' > packages/app/package.json
bun-1.4.0 install
rm -rf node_modules packages/*/node_modules
bun install --frozen-lockfile

Before: the error above, with the default (isolated) linker and with --linker=hoisted. After: exit 0, and bun.lock stays byte-identical to the 1.4.0 file. A plain install keeps it identical too.

Cross-version matrix (hoisted linker):

Lockfile written by	Step	Result
1.4.0	main, frozen	fails (both formats)
1.4.0	this PR, frozen	passes, lockfile unchanged, self-contained layout (both formats)
1.4.0	this PR, plain install	lockfile unchanged (both formats)
this PR	1.4.0, frozen	passes (both formats)
main, with the setting	this PR, frozen	bun.lock: passes. bun.lockb: fails once, a plain install repairs it

The last row needs a bun.lockb that a canary build wrote with the setting. Its meta hash has the names. A bun.lock from a canary build keeps its "hoistingLimits" keys until its next save. The parser ignores them, as 1.4.0 does.

Behavior change. A repo with the yarn key gets the self-contained layout on its first install with this version, with no lockfile diff. On main, the same layout comes after a plain install, with a lockfile diff.

Optional peers. The barrier can change which package an optional peer binds to (repro in the PR comments). resolve now binds without the barrier. So inside a self-contained workspace, the package that Node finds can differ from the binding in the lockfile, which bun why shows. Installs with --filter or --production can differ in the same way.

Design. The install owner chose this shape in the PR comments. The first version recorded the set in the lockfile, and a self-review of that version raised three concerns. This shape removes the first (a frozen pass for every set mismatch) and answers the third (this design question). The second is a separate change: hoistingLimits: "none", yarn's default, prints a warning on every install since #40014.

Suites run: bun-lockb, bun-lock, bun-pm, bun-prune, migrate-bun-lockb-v2, lockfile-version-2, lockfile-only, frozen-lockfile-pruned, frozen-lockfile-missing-workspace, bun-workspaces, isolated-install, catalogs, nested-overrides, migration/migrate. The two prune cases pass on main too. They fail when bun prune does not take the set from the manifests.

---

no test proof · iteration 0 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/cli/install/bun-workspaces-self-contained.test.ts

[robobun]

Reproduced on main (1.4.1-canary.1) with a lockfile that the 1.4.0 release binary wrote, and a workspace with installConfig.hoistingLimits: "workspaces":

• bun.lock, default linker and --linker=hoisted: error: lockfile had changes, but lockfile is frozen.
• bun.lockb, --linker=hoisted: the same error.

On this branch both frozen installs pass, the lockfile stays byte-identical, and the install applies the setting. The 10 new lockfile cases in test/cli/install/bun-workspaces-self-contained.test.ts fail on main and pass on this branch.

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---

Walkthrough

Changes

Self-contained workspace lockfile behavior

Layer / File(s)	Summary
Lockfile metadata and binary serialization src/install/lockfile.rs, src/install/lockfile/bun.lockb.rs	Lockfiles persist self-contained workspace package hashes. These names are excluded from the generated metadata hash.
Install-time workspace synchronization src/install/PackageManager/install_with_manager.rs	Non-frozen installs update and save the lockfile when the manifest workspace set changes. Frozen installs keep the recorded set.
Frozen-install coverage and documentation test/cli/install/bun-workspaces-self-contained.test.ts, docs/pm/workspaces.mdx	Tests cover text and binary lockfiles with hoisted and isolated linkers. Documentation describes frozen-install behavior and lockfile regeneration.

Suggested reviewers: jarred-sumner

Merge Risk: ⚪ Minimal · up to 6f67b

This change preserves the workspace layout recorded in the lockfile during frozen installs and updates it during non-frozen installs, preventing failures for workspace hoisting configurations while retaining lockfile compatibility. Both lockfile formats and migration scenarios are covered, with no known unresolved merge-readiness risk.

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✅ Passed checks (4 passed)

Check name	Status	Explanation
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.
Title check	✅ Passed	The title identifies the main lockfile behavior change: the hoisting setting is no longer stored as ordinary lockfile metadata. It is concise and directly related to the changes.
Description check	✅ Passed	The description clearly explains the problem, fix, design, compatibility behavior, reproduction steps, test coverage, and verification results. It does not use the template headings `### What does thi…

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Explanation

The description clearly explains the problem, fix, design, compatibility behavior, reproduction steps, test coverage, and verification results. It does not use the template headings ### What does this PR do? and ### How did you verify your code works?, but it provides the required information in equivalent sections.

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@docs/pm/workspaces.mdx`:
- Line 131: Update the workspace hoisting documentation to state that the
setting is recorded in both bun.lock and bun.lockb, so frozen installs using
either lockfile format reproduce the same layout.

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[claude]

I reviewed this PR and didn't find any bugs. Because it changes the bun.lockb on-disk format (new trailing section) and reworks how --frozen-lockfile reconciles the self-contained-workspaces set against manifests — both with cross-version compatibility implications — a human look would still be worthwhile.

What was reviewed:

• New HAS_SELF_CONTAINED_WORKSPACES_TAG section in bun.lockb.rs — save/load ordering matches the existing tag-probe-then-rewind pattern (appended last, older readers stop before it, newer readers rewind on mismatch).
• Set-change detection in install_with_manager.rs — count + membership check is a correct set-equality test given ArrayHashMap keys are unique; FORCE_SAVE_LOCKFILE is only set when the set actually differs.
• Removed meta-hash input in lockfile.rs — both the count and append phases were deleted symmetrically; no dangling SELF_CONTAINED_BEGIN references remain.
• New tests use the local dummy registry, assert stderr before exit code, and gate the hardlink nlink check behind !isWindows.

Extended reasoning...

Overview

This PR fixes bun install --frozen-lockfile failing on lockfiles written by Bun 1.4.0 when a workspace's package.json declares installConfig.hoistingLimits: "workspaces". It moves the self-contained-workspaces set out of the bun.lockb meta-hash input (where no release ever had it) into a new tagged trailing section, and gates the mirror-from-manifests step so frozen installs use the recorded set verbatim while non-frozen installs only rewrite + force-save when the set actually changed. Docs are updated and 7 new parametrized test cases cover both lockfile formats, both linkers, and both directions of adding/removing the setting.

Security risks

None identified. The change reads a length-prefixed u64 array via the existing buffers::read_array helper (same as every other trailing section), and the data is workspace name hashes derived from the user's own manifests. No untrusted network input, no path construction from lockfile data in the changed code.

Level of scrutiny

High. Binary lockfile format changes and --frozen-lockfile semantics are load-bearing for CI reproducibility across the ecosystem, and the PR's own description documents a cross-version compatibility matrix with one acknowledged new failure case (a bun.lockb written by a canary build of main with the setting). The code follows established patterns closely — the new load/save block is byte-for-byte the same shape as HAS_SCOPED_OVERRIDES_TAG — but a maintainer familiar with the install path should confirm the frozen/non-frozen split and the decision not to bump a format version (the tag-probe pattern is designed for this, and prior optional-section additions did not bump one).

Other factors

Test coverage is thorough: describe.each over [hoisted|isolated] × [bun.lock|bun.lockb], plus a dedicated case where the hoisted tree shape is unchanged but the lockfile must still record the setting so frozen installs copy rather than hardlink. Tests assert stderr content before exit codes, use the local dummyRegistry, and the nlink assertion is correctly gated on !isWindows. The removed meta-hash code is fully deleted (both count and append phases), leaving no dead references.

[robobun]

^{Updated 8:54 PM PT - Sep 2nd, 2026}

@robobun, your commit 0088d4b is building: #109611

[dylan-conway]

does selfContained and/or hoistingLimits change the internal resolved lockfile resolutions?

[robobun]

@dylan-conway Yes, for optional peers. The setting does not change which packages are resolved.

• The resolver does not read the set. The manifest parser, the lockfile reader and writers, the hoister, and the hoisted installer (copy backend) use it.
• The hoister uses the set as a hoisting barrier. Tree::hoist_dependency (src/install/lockfile/Tree.rs:970) walks up to hoist_root_id, and a self-contained workspace sets that root at its own tree (Tree.rs:658). For regular dependencies and required peers, only the placement changes (buffers.trees, buffers.hoisted_dependencies).
• An optional peer is different. The walk binds it to the same-named package it can see (Resolve, ResolveReplace, Rebind). The barrier hides the packages above the workspace, so buffers.resolutions can change for an optional peer.

Repro with the hoisted linker on main. The root depends on utf-8-validate@6.0.4. Workspace app depends on ws@8.18.0 and utf-8-validate@5.0.10. ws has an optional peer on utf-8-validate.

• Without the setting, bun why utf-8-validate binds the peer of ws to 6.0.4.
• With installConfig.hoistingLimits: "workspaces" on app, it binds the peer to 5.0.10.
• The package list is the same in both projects. The meta hash on this branch is the same too.
• The isolated linker links 5.0.10 in both projects. It binds optional peers itself, so its layout does not change.

For this PR:

• A frozen install now hoists with the recorded set on both sides. So it keeps the optional-peer bindings that the lockfile recorded. On main it hoisted with the manifests' set.
• The meta hash covers the package list and the root scripts. It does not cover buffers.resolutions. So the names in the hash did not cover these bindings either. They only signalled that the setting changed. The recorded set now does that job.

[dylan-conway]

to clarify, these settings change the result of both Lockfile::resolve and Lockfile::filter?

[robobun]

@dylan-conway Yes, both. Both call Lockfile::hoist, which gives self_contained_workspace_ids() to the builder for every BuilderMethod (src/install/lockfile.rs:1370 on this branch). Only resolve can change buffers.resolutions:

• Lockfile::resolve (Resolvable): the barrier changes the placements. It can also change an optional-peer binding (Resolve, ResolveReplace, Rebind). That is the case from my last comment.
• Lockfile::filter (Filter): the barrier changes the placements only. filter skips an unresolved dependency (src/install/lockfile/Tree.rs:725), so Resolve, ResolveLater, and ResolveReplace cannot occur. Rebind is Resolvable only (Tree.rs:1039). So filter reads the bindings that resolve wrote, and it writes none.

So the two calls need the same set. Otherwise the optional-peer bindings from resolve do not match the placements from filter. In an install, resolve runs in clean_with_logger, and filter runs later in hoisted_install.rs:92. Both read manager.lockfile. With this PR that set is the recorded set in a frozen install, and the manifests' set in every other install.

On main, a frozen install from bun.lock used two sets. The parser's resolve used the recorded set. clean_with_logger and filter used the manifests' set. The frozen check compares the trees from the first two hoists, so it failed.

[robobun]

@dylan-conway A correction to my last comment, and a design question for you.

Correction. I wrote that resolve and filter need the same set. That is too strong. filter never rebinds an optional peer, and it already places packages differently from resolve when it filters (--filter, --production). With a different set, the optional-peer bindings do not match the placements, and bun why reports the binding from resolve. Nothing fails.

Design question. The barrier can apply in filter only (Tree.rs:658, gated on BuilderMethod::Filter). Then the setting does not change bun.lock, and this regression does not occur. For a repo that upgrades from 1.4.0 with the yarn key in a manifest, the two shapes differ:

	This PR	Barrier in filter only
bun.lock	Records the setting	Does not change
First frozen install on 1.4.1	Keeps the 1.4.0 layout	Applies the setting
The layout changes	After a plain bun install, with a lockfile diff	On the upgrade, with no lockfile diff
bun.lockb	New trailing section	No format change
bun why, bun pm ls	Show the self-contained tree	Show the hoisted tree

Both shapes remove the names from the meta hash. The filter-only shape also makes the "hoistingLimits" key in bun.lock unnecessary. #40014 added that key, and no release has it yet.

Which shape do you want?

Until you answer, I will narrow this PR to the regression. A frozen install passes with a note only when the lockfile records no self-contained set. That is the only case that a 1.4.0 lockfile produces. When the lockfile records a set and the manifests change it, the frozen install fails, as #40014 chose (review comment). At the moment this PR also accepts that second case.

[claude]

Code review found no issues

No high-confidence issues detected in this change.

[dylan-conway]

my thinking: normally we don't serialize settings to the lockfile like these, so i'm wondering if we should not write them to the lockfile?

[robobun]

@dylan-conway That works if the barrier moves to Lockfile::filter. Then nothing in the lockfile depends on the setting:

• resolve ignores the set. The tree in bun.lock, the optional-peer bindings, and the meta hash are the same with and without the setting.
• filter applies the barrier at install time, and the copy backend still reads the set. Every install reads the set from the manifests, a frozen install too.
• bun.lock stops writing "hoistingLimits", and the new bun.lockb section goes away. No release wrote either one.
• bun pm prune must read the manifests' set too. It hoists with filter and removes what the tree does not hold. Today it uses the set from the lockfile.

The frozen check then has no set to compare. So the regression, the note, and the new failure all go away. One behavior change stays: a repo with the yarn key gets the self-contained layout on its first 1.4.1 install, with no lockfile diff.

I will switch this PR to that shape now, and post the results here.

[dylan-conway]

sounds great. this is how it should work. and what about selfContained workspaces?

[robobun]

@dylan-conway workspaces.selfContained takes the same path. The root list and the yarn key fill one set while the root manifest is parsed (src/install/lockfile/Package.rs:2441, then Package.rs:2894). So the root list stays out of the lockfile too, and every install reads it from package.json.

The switch is pushed in 0088d4b:

• Lockfile::hoist gives the barrier list to the Filter method only (src/install/lockfile.rs:1365).
• bun.lock no longer writes or reads "hoistingLimits". The meta hash has no names, and bun.lockb has no new section.
• bun prune takes the set from the manifests (src/install/prune.rs:599). Without that, prune deletes packages from a self-contained workspace. Two new test cases cover it.

Results, for both spellings:

• A bun.lock and a bun.lockb that 1.4.0 wrote pass --frozen-lockfile. The lockfile stays byte-identical, and the install applies the setting.
• The lockfile is byte-identical with and without the setting.
• All of test/cli/install/bun-workspaces-self-contained.test.ts passes. The 10 new lockfile cases fail on main.

[dylan-conway]

great. this follows the usual pattern where hoist is the full resolution tree and filter is with settings applied

[robobun]

@dylan-conway Thanks. The comment in Lockfile::hoist now states that rule for the barrier. CI is running on 0088d4b. The two builds before it passed. I will request your review when this one is green.

[dylan-conway]

to confirm, with this pr nothing has been added to the lockfiles since v1.4.0 right?

[robobun]

@dylan-conway Right. With this PR, neither lockfile format has an addition since v1.4.0:

• bun.lock: no new key, and the same lockfileVersion and configVersion. The writer and the parser have no "hoistingLimits" code.
• bun.lockb: src/install/lockfile/bun.lockb.rs is identical to bun-v1.4.0, so there is no new section. The binary package serializer has no change either.
• Meta hash: generate_meta_hash is identical to bun-v1.4.0.

I also compared real files. A fresh install by the 1.4.0 release and by this branch writes byte-identical files, for bun.lock and for bun.lockb, with the yarn key and with workspaces.selfContained. The test project also has a dev dependency and trustedDependencies. The install on this branch still applies the self-contained layout.

Three commits since v1.4.0 can change the content for some projects. None of them adds a field:

• install: sort workspace deps by resolved name when writing bun.lock #40809 sorts the dependencies of a workspace by name when it writes bun.lock.
• install: dedupe a peer bound to a folder package instead of nesting a second copy #40564 dedupes a peer that is bound to a folder package, so the tree can change.
• install: read patchedDependencies from the root package.json only #39816 reads patchedDependencies from the root package.json only.

[claude]

This pull request has been reviewed before and this review found new issues. Where they share a root cause, one fix may close them together.

[claude]

🔴 Dropping the barrier from the Resolvable tree makes remove_collapsed_copies delete parts of a self-contained workspace's node_modules: after bun update/bun dedupe/bun audit fix with the hoisted linker, any package in <ws>/node_modules that is also installed at the root is treated as a collapsed duplicate and removed, so the workspace is no longer self-contained (base kept it because both trees carried the barrier). Fix: make the post-install collapsed-copy pass reason about the barrier-applied layout — e.g. skip workspaces in self_contained_workspaces (and their subtrees) in prune::remove_collapsed_copies, or compare against a Filter-built tree there.

Extended reasoning...

Repo: root and workspace web depend on bar@ 0.0.2; workspace desktop (self-contained via installConfig.hoistingLimits) transitively depends on bar@ 0.0.2 (same test fixture in bun-workspaces-self-contained.test.ts). bun install lays out node_modules/bar and apps/desktop/node_modules/bar. Run bun update. install_hoisted_packages runs filter() (barrier applied) so both copies are (re)installed, then its scopeguard restores manager.lockfile.buffers.trees to the resolve() output from Cloner::flush, which after this change is built with self_contained = Vec::new(). remove_collapsed_copies (install_with_manager.rs:899, gated on Dedupe/Audit/Update) therefore builds new from a barrier-less tree: no tree exists at node_modules/desktop/node_modules (surviving = None) and old_rows is empty. Its workspace pass (prune.rs:1378-1398) scans apps/desktop/node_modules; for bar, was_row = false, so it evaluates !new.collapsed_into_ancestor(0, "bar"). bar is expected at root in the barrier-less new and verified_installed finds node_modules/bar…

Verification: normal — the diff at src/install/lockfile.rs:1364-1369 gates self_contained_workspace_ids() to BuilderMethod::Filter only, so resolve() (line 1329, Resolvable) now builds a barrier-less tree. The base version (git show e26b4e1:src/install/lockfile.rs, let self_contained = self.self_contained_workspace_ids(); was unconditional) applied the barrier to both. Trace on `bun update… | normal…