[BUG] `--omit=dev` silently ignored with `install-strategy=linked`

[manzoorwanijk]

Is there an existing issue for this?

• I have searched the existing issues
• I am using the latest npm

Related to #9063

Current Behavior

npm install --omit=dev with install-strategy=linked installs all dependencies including devDependencies. The flag is silently ignored — dev packages appear in node_modules/.store/ and are symlinked as normal.

Expected Behavior

Dev dependencies should not be installed, same as with the default hoisted strategy.

Steps To Reproduce

mkdir -p /tmp/repro/packages/my-lib && cd /tmp/repro

cat > package.json << 'EOF'
{
  "name": "my-monorepo",
  "private": true,
  "workspaces": ["packages/*"],
  "dependencies": {
    "abbrev": "^2.0.0"
  },
  "devDependencies": {
    "semver": "^7.6.0"
  }
}
EOF

cat > packages/my-lib/package.json << 'EOF'
{
  "name": "my-lib",
  "version": "1.0.0",
  "dependencies": {
    "abbrev": "^2.0.0"
  },
  "devDependencies": {
    "lru-cache": "^10.0.0"
  }
}
EOF

echo "install-strategy=linked" > .npmrc

npm install --omit=dev
ls node_modules/.store/
# Expected: only abbrev
# Actual:   abbrev, lru-cache, semver (dev deps included)

For comparison, removing install-strategy=linked from .npmrc and running the same command correctly omits semver and lru-cache.

Root Cause

The isolated reifier builds its proxy tree from idealGraph which contains all resolved dependencies. It never checks the omit option — dev dependencies are unconditionally included. The proxy nodes also lack dev/optional/peer edge metadata, so Diff.calculate() can't filter them either.

Environment

• npm: 11.x (latest) and 10.9.5 — both affected
• Node.js: 22.20.0
• OS Name: macOS (Darwin 25.3.0)
• npm config:

  install-strategy=linked