fix: skip re-importing packages when global virtual store is warm (#10709)

* fix: skip re-importing packages when global virtual store is warm

When node_modules is deleted but the global virtual store directories
survive, pnpm previously re-fetched every package because the skip
logic required currentLockfile to be present. Add a fast-path that
checks pathExists(dir) for GVS directories even when currentLockfile
is missing, since the GVS directory hash encodes engine, integrity,
and full dependency subgraph.

* fix: remove includeUnchangedDeps guard from GVS fast-path

The includeUnchangedDeps flag is true whenever currentHoistPattern
differs from the desired hoistPattern. After deleting node_modules,
currentHoistPattern is always undefined (read from .modules.yaml),
so the flag is always true when hoisting is configured — defeating
the optimization in the exact scenario it targets.

The guard is unnecessary because the fast-path only skips fetch/import
(fetchResponse = {}), not graph inclusion. The package is still added
to the graph with children populated, so hoisting recalculation works.

* perf: add GVS warm reinstall benchmark scenario

Adds benchmark 6: frozen lockfile reinstall with a warm global virtual
store after deleting node_modules. This measures the reattach fast-path
where all packages are skipped (no fetch/import) because their GVS
hash directories already exist.

* fix: use proper types in fetchPackage spy to pass tsgo strict checks

.changeset/global-virtual-store-reattach.md

@@ -0,0 +1,6 @@
+---
+"@pnpm/graph-builder": patch
+"pnpm": patch
+---
+
+Skip re-importing packages from the global virtual store when `node_modules` is deleted but the store directories are still warm. The global store directory hash already encodes engine, integrity, and full dependency subgraph, so existence is proof of validity.

benchmarks/bench.sh

@@ -228,6 +228,49 @@ run_bench "cold" \
   "rm -rf {project}/node_modules {project}/pnpm-lock.yaml {store} {cache} && cp $BENCH_DIR/original-package.json {project}/package.json" \
   "cd {project} && node {bin} install --ignore-scripts --no-frozen-lockfile >/dev/null 2>&1"
 
+# ── Benchmark 6: GVS warm reinstall ───────────────────────────────────────
+# Global virtual store enabled, GVS warm, node_modules deleted.
+# This tests the reattach fast-path: all packages should be skipped
+# (no fetch/import) because their GVS hash directories already exist.
+
+echo ""
+echo "━━━ Benchmark 6: GVS warm reinstall (frozen lockfile, warm global virtual store) ━━━"
+
+# Set up separate GVS-enabled project directories per variant
+GVS_PROJECTS=()
+for i in "${!VARIANTS[@]}"; do
+  gvs_dir="$BENCH_DIR/project-gvs-${VARIANTS[$i]}"
+  mkdir -p "$gvs_dir"
+  cp "$BRANCH_DIR/benchmarks/fixture.package.json" "$gvs_dir/package.json"
+  printf "storeDir: %s\ncacheDir: %s\nenableGlobalVirtualStore: true\n" \
+    "${VARIANT_STORES[$i]}" "${VARIANT_CACHES[$i]}" > "$gvs_dir/pnpm-workspace.yaml"
+  GVS_PROJECTS+=("$gvs_dir")
+
+  # Warm the GVS with a full install
+  echo "Warming GVS for ${VARIANTS[$i]}..."
+  cd "$gvs_dir" && node "${VARIANT_BINS[$i]}" install --ignore-scripts --no-frozen-lockfile >/dev/null 2>&1
+  cp "$gvs_dir/pnpm-lock.yaml" "$BENCH_DIR/saved-lockfile-gvs-${VARIANTS[$i]}.yaml"
+done
+
+for i in "${!VARIANTS[@]}"; do
+  variant="${VARIANTS[$i]}"
+  gvs_project="${GVS_PROJECTS[$i]}"
+  bin="${VARIANT_BINS[$i]}"
+  lockfile="$BENCH_DIR/saved-lockfile-gvs-$variant.yaml"
+
+  echo ""
+  echo "  $variant:"
+  hyperfine \
+    --warmup "$WARMUP" \
+    --runs "$RUNS" \
+    --ignore-failure \
+    --prepare "rm -rf $gvs_project/node_modules && cp $lockfile $gvs_project/pnpm-lock.yaml" \
+    --command-name "$variant" \
+    "cd $gvs_project && node $bin install --frozen-lockfile --ignore-scripts >/dev/null 2>&1" \
+    --export-json "$BENCH_DIR/gvs-warm-${variant}.json" \
+    || true
+done
+
 # ── Summary ─────────────────────────────────────────────────────────────────
 
 RESULTS_MD="$BENCH_DIR/results.md"
@@ -239,7 +282,7 @@ echo ""
 echo "Results saved to: $RESULTS_MD"
 
 # Cleanup
-for project in "${VARIANT_PROJECTS[@]}"; do
+for project in "${VARIANT_PROJECTS[@]}" "${GVS_PROJECTS[@]}"; do
   rm -rf "$project/node_modules"
 done
 echo ""

benchmarks/generate-results.js

@@ -9,6 +9,7 @@ const benchmarks = [
   ['nolockfile', 'Full resolution (warm, no lockfile)'],
   ['headless-cold', 'Headless (cold store+cache)'],
   ['cold', 'Cold install (nothing warm)'],
+  ['gvs-warm', 'GVS warm reinstall (warm global store)'],
 ]
 
 function readResult (benchDir, name, variant) {

deps/graph-builder/src/lockfileToDepGraph.ts

@@ -256,6 +256,13 @@ async function buildGraphFromPackages (
         }
       }
 
+      if (!fetchResponse && opts.enableGlobalVirtualStore && !isDirectoryDep
+        && !opts.force) {
+        if (dirExists ?? await pathExists(dir)) {
+          fetchResponse = {}
+        }
+      }
+
       if (!fetchResponse) {
         const resolution = pkgSnapshotToResolution(depPath, pkgSnapshot, opts.registries)
         progressLogger.debug({ packageId, requester: opts.lockfileDir, status: 'resolved' })

pkg-manager/core/test/install/globalVirtualStore.ts

@@ -49,6 +49,50 @@ test('using a global virtual store', async () => {
   }
 })
 
+test('reinstall from warm global virtual store after deleting node_modules', async () => {
+  prepareEmpty()
+  const globalVirtualStoreDir = path.resolve('links')
+  const manifest = {
+    dependencies: {
+      '@pnpm.e2e/pkg-with-1-dep': '100.0.0',
+    },
+  }
+  const opts = testDefaults({
+    enableGlobalVirtualStore: true,
+    virtualStoreDir: globalVirtualStoreDir,
+    hoistPattern: ['*'],
+  })
+  await install(manifest, opts)
+
+  // Delete only node_modules, keep the global virtual store warm
+  rimraf('node_modules')
+  expect(fs.existsSync(globalVirtualStoreDir)).toBeTruthy()
+
+  // Spy on fetchPackage to verify the fast-path skips fetching
+  const originalFetchPackage = opts.storeController.fetchPackage
+  let fetchPackageCalls = 0
+  opts.storeController.fetchPackage = ((fetchOpts) => {
+    fetchPackageCalls++
+    return originalFetchPackage(fetchOpts)
+  }) as typeof originalFetchPackage
+
+  // Reinstall with frozenLockfile — should reattach from the warm global store
+  await install(manifest, {
+    ...opts,
+    frozenLockfile: true,
+  })
+
+  // fetchPackage should NOT be called — all packages reattached from warm GVS
+  expect(fetchPackageCalls).toBe(0)
+
+  expect(fs.existsSync(path.resolve('node_modules/.pnpm/node_modules/@pnpm.e2e/dep-of-pkg-with-1-dep/package.json'))).toBeTruthy()
+  expect(fs.existsSync(path.resolve('node_modules/.pnpm/lock.yaml'))).toBeTruthy()
+  const files = fs.readdirSync(path.join(globalVirtualStoreDir, '@pnpm.e2e/pkg-with-1-dep/100.0.0'))
+  expect(files).toHaveLength(1)
+  expect(fs.existsSync(path.join(globalVirtualStoreDir, '@pnpm.e2e/pkg-with-1-dep/100.0.0', files[0], 'node_modules/@pnpm.e2e/pkg-with-1-dep/package.json'))).toBeTruthy()
+  expect(fs.existsSync(path.join(globalVirtualStoreDir, '@pnpm.e2e/pkg-with-1-dep/100.0.0', files[0], 'node_modules/@pnpm.e2e/dep-of-pkg-with-1-dep/package.json'))).toBeTruthy()
+})
+
 test('modules are correctly updated when using a global virtual store', async () => {
   prepareEmpty()
   const globalVirtualStoreDir = path.resolve('links')