[BUG] linked strategy: non-idempotent install with workspace projects

[manzoorwanijk]

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

Running npm install --install-strategy=linked repeatedly on a workspace project always reports changed N packages even when nothing has actually changed. The dry-run output shows it "changing" packages to the exact same version (e.g. change abbrev 2.0.0 => 2.0.0), and reports duplicate entries for some packages.

This does not happen for non-workspace projects, which correctly report up to date.

Expected Behavior

Repeated installs with no changes should report up to date, audited N packages as it does for non-workspace projects and for other install strategies.

Steps To Reproduce

1. Create a workspace project with cross-workspace dependencies:

mkdir -p test-diamond/packages/{workspace-x,workspace-y}

cat > test-diamond/package.json << 'EOF'
{
  "name": "test-diamond",
  "version": "1.0.0",
  "workspaces": ["packages/*"],
  "dependencies": { "workspace-x": "*", "workspace-y": "*" }
}
EOF

cat > test-diamond/packages/workspace-x/package.json << 'EOF'
{
  "name": "workspace-x",
  "version": "1.0.0",
  "dependencies": { "abbrev": "^2.0.0", "workspace-y": "*" }
}
EOF

cat > test-diamond/packages/workspace-y/package.json << 'EOF'
{
  "name": "workspace-y",
  "version": "1.0.0",
  "dependencies": { "abbrev": "^2.0.0" }
}
EOF

2. Install and then install again:

cd test-diamond
npm install --install-strategy=linked
npm install --install-strategy=linked

3. Second install reports changed 5 packages instead of up to date.

4. Dry-run confirms the false diff:

npm install --install-strategy=linked --dry-run

Output:

change abbrev 2.0.0 => 2.0.0
change workspace-y 1.0.0 => 1.0.0
change abbrev 2.0.0 => 2.0.0
change workspace-y 1.0.0 => 1.0.0
change workspace-x 1.0.0 => 1.0.0

changed 5 packages

Environment

• npm: 11.11.0
• Node.js: v22.20.0
• OS Name: macOS (Darwin 25.3.0)
• System Model Name: Mac
• npm config:

install-strategy=linked