test(snapshots): isolate npm network cases

crates/vp_cli_snapshots/tests/cli_snapshots/README.md

@@ -83,6 +83,7 @@ cwd = "packages/app"          # optional, relative to the fixture root
 skip-platforms = ["windows"]  # or { os = "linux", libc = "musl" }
 requires = ["bash"]           # "sh" | "bash" | "zsh" | "cmd" | "fish" | "nu" | "pwsh"
 ignore = false                # true: only runs with `-- --ignored`
+serial = false                # true: run alone across cargo test/nextest workers
 seed-runtime = true           # false: start from an empty VP_HOME
 link-node-modules = false     # true: expose the run-root node_modules as
                               #   the workspace's parent-dir node_modules,

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_add_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_add_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "add", "--help"], comment = "should show help", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_add_npm10_with_workspace/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_add_npm10_with_workspace"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "add", "testnpm2", "-D", "-w", "--", "--no-audit"], comment = "should add package to workspace root" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_cache_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_cache_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "pm", "cache", "dir"], comment = "should show cache directory (uses npm config get cache)", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_config_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_config_npm10"
 vp = "global"
+serial = true
 steps = [
   { argv = ["vp", "pm", "config", "--help"], comment = "should show help", continue-on-failure = true },
   { argv = ["vp", "pm", "config", "get", "vite-plus-pm-config-test-key", "--location", "project"], comment = "should get config value from project scope", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_dedupe_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_dedupe_npm10"
 vp = "global"
+serial = true
 steps = [
   { argv = ["vp", "dedupe"], comment = "should dedupe dependencies" },
   { argv = ["vpt", "print-file", "package.json"], continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_dlx_no_package_json/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_dlx_no_package_json"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "dlx", "-s", "cowsay", "hello"], comment = "should work without package.json", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_dlx_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_dlx_npm10"
 vp = "global"
+serial = true
 local-registry = true
 skip-platforms = ["windows", { os = "linux", libc = "musl" }]
 steps = [

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_link_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_link_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vpt", "mkdir", "-p", "../test-lib-npm"], comment = "create test library" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_list_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_list_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "install"], comment = "should install packages first", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_list_npm10_with_workspace/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_list_npm10_with_workspace"
 vp = "global"
+serial = true
 steps = [
   { argv = ["vp", "install"], comment = "should install packages first", continue-on-failure = true },
   { argv = ["vp", "pm", "list", "--json"], comment = "should list current workspace root dependencies", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_outdated_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_outdated_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "install"], comment = "should install packages first", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_outdated_npm10_with_workspace/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_outdated_npm10_with_workspace"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "install"], continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_owner_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_owner_npm10"
 vp = "global"
+serial = true
 steps = [
   { argv = ["vp", "pm", "owner", "list", "testnpm2"], comment = "should list package owners", continue-on-failure = true },
 ]

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_pack_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_pack_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "pm", "pack", "--json"], comment = "should pack current package" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_pack_npm10_with_workspace/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_pack_npm10_with_workspace"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "pm", "pack", "--json"], comment = "should pack current workspace root", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_prune_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_prune_npm10"
 vp = "global"
+serial = true
 steps = [
   { argv = ["vp", "install"], comment = "should install packages first", continue-on-failure = true },
   { argv = ["vp", "pm", "prune", "--help"], comment = "should show help", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_publish_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_publish_npm10"
 vp = "global"
+serial = true
 steps = [
   { argv = ["vp", "pm", "publish", "--help"], comment = "should show help", continue-on-failure = true },
   { argv = ["vp", "pm", "publish", "--dry-run", "--", "--loglevel", "error"], comment = "should preview publish without actually publishing (uses npm publish --dry-run)", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_remove_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_remove_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "remove", "testnpm2", "-D", "--", "--no-audit"], comment = "should pass when remove not exists package" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_remove_npm10_with_workspace/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_remove_npm10_with_workspace"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "add", "testnpm2", "-D", "-w", "--filter=*", "--", "--no-audit"], comment = "prepare packages" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_unlink_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_unlink_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vpt", "mkdir", "-p", "../unlink-test-lib-npm"], comment = "create test library" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_update_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_update_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "update", "testnpm2", "--", "--no-audit"], comment = "should update package within semver range" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_update_npm10_with_workspace/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_update_npm10_with_workspace"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "update", "testnpm2", "-w", "--", "--no-audit"], comment = "should update in workspace root" },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_view_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_view_npm10"
 vp = "global"
+serial = true
 steps = [
   { argv = ["vp", "pm", "view", "testnpm2", "dist.tarball"], comment = "should view testnpm2 package information", continue-on-failure = true },
   { argv = ["vp", "pm", "info", "testnpm2", "dist.tarball"], comment = "should info alias to view", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_vpx_no_package_json/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_vpx_no_package_json"
 vp = "global"
+serial = true
 local-registry = true
 skip-platforms = ["windows"]
 steps = [

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_why_npm10/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_why_npm10"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "install"], comment = "should install packages first", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_why_npm10_with_workspace/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "command_why_npm10_with_workspace"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 steps = [
   { argv = ["vp", "install"], continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/migration_standalone_npm/package.json

@@ -4,5 +4,5 @@
     "vite": "^7.0.0",
     "vitest": "^4.0.0"
   },
-  "packageManager": "npm@10.9.2"
+  "packageManager": "npm@11.13.0"
 }

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/migration_standalone_npm/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "migration_standalone_npm"
 vp = "global"
+serial = true
 skip-platforms = ["windows"]
 unset-env = ["CI", "VP_SKIP_INSTALL"]
 local-registry = true

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/migration_standalone_npm/snapshots/migration_standalone_npm.md

@@ -30,7 +30,7 @@ check package.json has overrides field (not pnpm.overrides)
   "overrides": {
     "vite": "npm:@voidzero-dev/vite-plus-core@<version>"
   },
-  "packageManager": "npm@10.9.2"
+  "packageManager": "npm@11.13.0"
 }
 ```
 

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/npm_install_with_options/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "npm_install_with_options"
 vp = "local"
+serial = true
 steps = [
   { argv = ["vp", "install", "--help"], comment = "print help message", continue-on-failure = true },
   { argv = ["vp", "run", "install"], comment = "https://docs.npmjs.com/cli/v10/commands/npm-install", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/pm_audit/snapshots.toml

@@ -1,6 +1,7 @@
 [[case]]
 name = "pm_audit_bun"
 vp = "global"
+serial = true
 cwd = "bun"
 steps = [
   { argv = ["vp", "install", "--", "--silent"], comment = "should install packages first", continue-on-failure = true },

crates/vp_cli_snapshots/tests/cli_snapshots/main.rs

@@ -20,8 +20,10 @@ mod flavor;
 mod redact;
 
 use std::{
-    collections::BTreeMap,
+    collections::{BTreeMap, hash_map::DefaultHasher},
     ffi::OsString,
+    fs::{File, OpenOptions},
+    hash::{Hash, Hasher},
     io::Write,
     path::{Path, PathBuf},
     sync::{Arc, Mutex, mpsc},
@@ -1530,33 +1532,56 @@ fn run_case(
 /// on Linux: only the few signal-sensitive cases pay for serialization, while
 /// the rest parallelize as they already do on macOS and Windows.
 ///
-/// This coordinates threads within a single `cargo test` process, which is the
-/// Linux and macOS snapshot jobs and the only place the parallel-PTY
-/// signal-routing flakiness occurs. The Windows job runs the suite under
-/// `cargo nextest`, which executes each trial in its own process; there the
-/// gate is a no-op, but isolation is stronger for free — a signal-sensitive
-/// case already has its own process, PTY, and process group, which is exactly
-/// what this gate reconstructs for the shared-process case.
+/// The in-process lock coordinates the threads used by `cargo test`. A matching
+/// file lock coordinates the separate trial processes used by `cargo nextest`
+/// on Windows. The lock file name includes the checkout path so independent
+/// worktrees do not block each other.
 static EXECUTION_GATE: std::sync::RwLock<()> = std::sync::RwLock::new(());
 
 /// Held for a case's whole run: either a shared read lease (parallel) or the
 /// exclusive write lease (isolated). Poisoning is ignored — a case that
 /// panicked already failed, and its neighbours should still run.
 enum GateLease {
-    Shared(
-        #[expect(dead_code, reason = "held for its Drop")] std::sync::RwLockReadGuard<'static, ()>,
-    ),
-    Exclusive(
-        #[expect(dead_code, reason = "held for its Drop")] std::sync::RwLockWriteGuard<'static, ()>,
-    ),
+    Shared {
+        #[expect(dead_code, reason = "held for its Drop")]
+        thread: std::sync::RwLockReadGuard<'static, ()>,
+        #[expect(dead_code, reason = "held for its Drop")]
+        process: File,
+    },
+    Exclusive {
+        #[expect(dead_code, reason = "held for its Drop")]
+        thread: std::sync::RwLockWriteGuard<'static, ()>,
+        #[expect(dead_code, reason = "held for its Drop")]
+        process: File,
+    },
+}
+
+fn execution_gate_file() -> File {
+    let mut hasher = DefaultHasher::new();
+    flavor::repo_root().hash(&mut hasher);
+    let path = std::env::temp_dir()
+        .join(format!("vp-cli-snapshots-execution-{:016x}.lock", hasher.finish()));
+    OpenOptions::new()
+        .create(true)
+        .read(true)
+        .write(true)
+        .truncate(false)
+        .open(&path)
+        .unwrap_or_else(|error| panic!("failed to open execution gate {}: {error}", path.display()))
 }
 
 fn acquire_gate(isolated: bool) -> GateLease {
     use std::sync::PoisonError;
     if isolated {
-        GateLease::Exclusive(EXECUTION_GATE.write().unwrap_or_else(PoisonError::into_inner))
+        let thread = EXECUTION_GATE.write().unwrap_or_else(PoisonError::into_inner);
+        let process = execution_gate_file();
+        File::lock(&process).expect("failed to lock the cross-process execution gate");
+        GateLease::Exclusive { thread, process }
     } else {
-        GateLease::Shared(EXECUTION_GATE.read().unwrap_or_else(PoisonError::into_inner))
+        let thread = EXECUTION_GATE.read().unwrap_or_else(PoisonError::into_inner);
+        let process = execution_gate_file();
+        File::lock_shared(&process).expect("failed to lock the cross-process execution gate");
+        GateLease::Shared { thread, process }
     }
 }