diff --git a/crates/vite_global_cli/src/commands/env/config.rs b/crates/vite_global_cli/src/commands/env/config.rs
index e9b9b4b685..eabf328c47 100644
--- a/crates/vite_global_cli/src/commands/env/config.rs
+++ b/crates/vite_global_cli/src/commands/env/config.rs
@@ -258,29 +258,34 @@ pub async fn resolve_version(cwd: &AbsolutePath) -> Result<VersionResolution, Er
             });
         }
 
-        // Invalid .node-version - check package.json sources in the same directory
-        // This mirrors the fallback logic in download_runtime_for_project()
-        if matches!(resolution.source, VersionSource::NodeVersionFile) {
+        // Invalid version from a project source - try lower-priority sources in the same directory.
+        // This mirrors the fallback logic in download_runtime_for_project().
+        // - NodeVersionFile: try engines.node, then devEngines.runtime
+        // - EnginesNode: try devEngines.runtime
+        if matches!(resolution.source, VersionSource::NodeVersionFile | VersionSource::EnginesNode)
+        {
             if let Some(project_root) = &resolution.project_root {
                 let package_json_path = project_root.join("package.json");
                 if let Ok(Some(pkg)) = read_package_json(&package_json_path).await {
-                    // Try engines.node
-                    if let Some(engines_node) = pkg
-                        .engines
-                        .as_ref()
-                        .and_then(|e| e.node.clone())
-                        .and_then(|v| normalize_version(&v, "engines.node"))
-                    {
-                        let resolved = resolve_version_string(&engines_node, &provider).await?;
-                        let is_range = NodeProvider::is_lts_alias(&engines_node)
-                            || !NodeProvider::is_exact_version(&engines_node);
-                        return Ok(VersionResolution {
-                            version: resolved,
-                            source: "engines.node".into(),
-                            source_path: Some(package_json_path),
-                            project_root: Some(project_root.clone()),
-                            is_range,
-                        });
+                    // Try engines.node (only when falling back from .node-version)
+                    if matches!(resolution.source, VersionSource::NodeVersionFile) {
+                        if let Some(engines_node) = pkg
+                            .engines
+                            .as_ref()
+                            .and_then(|e| e.node.clone())
+                            .and_then(|v| normalize_version(&v, "engines.node"))
+                        {
+                            let resolved = resolve_version_string(&engines_node, &provider).await?;
+                            let is_range = NodeProvider::is_lts_alias(&engines_node)
+                                || !NodeProvider::is_exact_version(&engines_node);
+                            return Ok(VersionResolution {
+                                version: resolved,
+                                source: "engines.node".into(),
+                                source_path: Some(package_json_path),
+                                project_root: Some(project_root.clone()),
+                                is_range,
+                            });
+                        }
                     }
 
                     // Try devEngines.runtime
@@ -751,6 +756,30 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn test_resolve_version_invalid_engines_node_falls_through_to_dev_engines() {
+        let temp_dir = TempDir::new().unwrap();
+        let temp_path = AbsolutePathBuf::new(temp_dir.path().to_path_buf()).unwrap();
+        let _guard = vite_shared::EnvConfig::test_guard(
+            vite_shared::EnvConfig::for_test_with_home(temp_dir.path()),
+        );
+
+        // Create package.json with invalid engines.node but valid devEngines.runtime
+        // No .node-version file — resolve_node_version returns EnginesNode source
+        let package_json = r#"{"engines":{"node":"invalid"},"devEngines":{"runtime":{"name":"node","version":"^20.18.0"}}}"#;
+        tokio::fs::write(temp_path.join("package.json"), package_json).await.unwrap();
+
+        // resolve_version should fall through from invalid engines.node to devEngines.runtime
+        let resolution = resolve_version(&temp_path).await.unwrap();
+
+        assert_eq!(resolution.source, "devEngines.runtime");
+        assert!(
+            resolution.version.starts_with("20."),
+            "Expected version to start with '20.', got: {}",
+            resolution.version
+        );
+    }
+
     #[tokio::test]
     async fn test_resolve_version_latest_alias_in_node_version() {
         let temp_dir = TempDir::new().unwrap();
diff --git a/crates/vite_global_cli/src/js_executor.rs b/crates/vite_global_cli/src/js_executor.rs
index 871ba2002b..54693a75ef 100644
--- a/crates/vite_global_cli/src/js_executor.rs
+++ b/crates/vite_global_cli/src/js_executor.rs
@@ -6,11 +6,14 @@
 use std::process::ExitStatus;
 
 use tokio::process::Command;
-use vite_js_runtime::{JsRuntime, JsRuntimeType, download_runtime, download_runtime_for_project};
+use vite_js_runtime::{
+    JsRuntime, JsRuntimeType, download_runtime, download_runtime_for_project, is_valid_version,
+    read_package_json, resolve_node_version,
+};
 use vite_path::{AbsolutePath, AbsolutePathBuf};
 use vite_shared::{PrependOptions, PrependResult, env_vars, format_path_with_prepend};
 
-use crate::error::Error;
+use crate::{commands::env::config, error::Error};
 
 /// JavaScript executor using managed Node.js runtime.
 ///
@@ -134,15 +137,52 @@ impl JsExecutor {
 
     /// Ensure the project runtime is downloaded and cached.
     ///
-    /// Uses the project's package.json `devEngines.runtime` configuration
-    /// to determine which Node.js version to use.
+    /// Resolution order:
+    /// 1. Session override (env var from `vp env use`)
+    /// 2. Session override (file from `vp env use`)
+    /// 3. Project sources (.node-version, engines.node, devEngines.runtime) —
+    ///    delegates to `download_runtime_for_project()` for cache-aware resolution
+    /// 4. User default from config.json
+    /// 5. Latest LTS
     pub async fn ensure_project_runtime(
         &mut self,
         project_path: &AbsolutePath,
     ) -> Result<&JsRuntime, Error> {
         if self.project_runtime.is_none() {
             tracing::debug!("Resolving project runtime from {:?}", project_path);
-            let runtime = download_runtime_for_project(project_path).await?;
+
+            // 1–2. Session overrides: env var (from `vp env use`), then file
+            let session_version = vite_shared::EnvConfig::get()
+                .node_version
+                .map(|v| v.trim().to_string())
+                .filter(|v| !v.is_empty());
+            let session_version = if session_version.is_some() {
+                session_version
+            } else {
+                config::read_session_version().await
+            };
+            if let Some(version) = session_version {
+                let runtime = download_runtime(JsRuntimeType::Node, &version).await?;
+                return Ok(self.project_runtime.insert(runtime));
+            }
+
+            // 3. Check if project has any *valid* version source.
+            //    resolve_node_version returns Some for any non-empty value,
+            //    even invalid ones. We must validate before routing to
+            //    download_runtime_for_project, which falls to LTS on all-invalid
+            //    and would skip the user's configured default.
+            let has_valid_project_source = has_valid_version_source(project_path).await?;
+
+            let runtime = if has_valid_project_source {
+                // At least one valid project source exists — delegate to
+                // download_runtime_for_project for cache-aware range resolution
+                // and intra-project fallback chain
+                download_runtime_for_project(project_path).await?
+            } else {
+                // No valid project source — check user default from config, then LTS
+                let resolution = config::resolve_version(project_path).await?;
+                download_runtime(JsRuntimeType::Node, &resolution.version).await?
+            };
             self.project_runtime = Some(runtime);
         }
         Ok(self.project_runtime.as_ref().unwrap())
@@ -163,8 +203,7 @@ impl JsExecutor {
     /// If found, runs the local `dist/bin.js` directly. Otherwise, falls back
     /// to the global installation's `dist/bin.js`.
     ///
-    /// Uses the project's runtime (from its `devEngines.runtime` configuration).
-    /// This may write a `.node-version` file if the project has no version source.
+    /// Uses the project's runtime resolved via `config::resolve_version()`.
     /// For side-effect-free commands like `--version`, use [`delegate_with_cli_runtime`] instead.
     ///
     /// # Arguments
@@ -252,6 +291,48 @@ impl JsExecutor {
     }
 }
 
+/// Check whether a project directory has at least one valid version source.
+///
+/// Uses `is_valid_version` (no warning side effects) to avoid duplicate
+/// warnings when `download_runtime_for_project` or `config::resolve_version`
+/// later call `normalize_version` on the same values.
+///
+/// Returns `false` when all sources are missing or invalid, so the caller
+/// can fall through to the user's configured default instead of LTS.
+async fn has_valid_version_source(
+    project_path: &AbsolutePath,
+) -> Result<bool, vite_js_runtime::Error> {
+    let resolution = resolve_node_version(project_path, true).await?;
+    let Some(ref r) = resolution else {
+        return Ok(false);
+    };
+
+    // Primary source is a valid version?
+    if is_valid_version(&r.version) {
+        return Ok(true);
+    }
+
+    // Primary source invalid — check package.json for valid fallbacks
+    let pkg_path = project_path.join("package.json");
+    let Ok(Some(pkg)) = read_package_json(&pkg_path).await else {
+        return Ok(false);
+    };
+
+    let engines_valid =
+        pkg.engines.as_ref().and_then(|e| e.node.as_ref()).is_some_and(|v| is_valid_version(v));
+
+    let dev_engines_valid = !engines_valid
+        && pkg
+            .dev_engines
+            .as_ref()
+            .and_then(|de| de.runtime.as_ref())
+            .and_then(|rt| rt.find_by_name("node"))
+            .filter(|r| !r.version.is_empty())
+            .is_some_and(|r| is_valid_version(&r.version));
+
+    Ok(engines_valid || dev_engines_valid)
+}
+
 #[cfg(test)]
 mod tests {
     use serial_test::serial;
diff --git a/crates/vite_js_runtime/src/lib.rs b/crates/vite_js_runtime/src/lib.rs
index 4460080f49..71b7a488ec 100644
--- a/crates/vite_js_runtime/src/lib.rs
+++ b/crates/vite_js_runtime/src/lib.rs
@@ -51,6 +51,6 @@ pub use provider::{ArchiveFormat, DownloadInfo, HashVerification, JsRuntimeProvi
 pub use providers::{LtsInfo, NodeProvider, NodeVersionEntry};
 pub use runtime::{
     JsRuntime, JsRuntimeType, VersionResolution, VersionSource, download_runtime,
-    download_runtime_for_project, download_runtime_with_provider, normalize_version,
-    read_package_json, resolve_node_version,
+    download_runtime_for_project, download_runtime_with_provider, is_valid_version,
+    normalize_version, read_package_json, resolve_node_version,
 };
diff --git a/crates/vite_js_runtime/src/runtime.rs b/crates/vite_js_runtime/src/runtime.rs
index b6853693c6..443d14bf89 100644
--- a/crates/vite_js_runtime/src/runtime.rs
+++ b/crates/vite_js_runtime/src/runtime.rs
@@ -5,7 +5,7 @@ use vite_str::Str;
 
 use crate::{
     Error, Platform,
-    dev_engines::{PackageJson, read_node_version_file, write_node_version_file},
+    dev_engines::{PackageJson, read_node_version_file},
     download::{download_file, download_text, extract_archive, move_to_cache, verify_file_hash},
     provider::{HashVerification, JsRuntimeProvider},
     providers::NodeProvider,
@@ -384,8 +384,7 @@ pub async fn download_runtime_for_project(project_path: &AbsolutePath) -> Result
     tracing::debug!("Selected version source: {source:?}, version_req: {version_req:?}");
 
     // Resolve version (if range/partial → exact)
-    let (version, should_write_back) =
-        resolve_version_for_project(&version_req, source, &provider, &cache_dir).await?;
+    let version = resolve_version_for_project(&version_req, &provider, &cache_dir).await?;
 
     // Check compatibility with lower priority sources
     check_version_compatibility(&version, source, &engines_node, &dev_engines_runtime);
@@ -393,71 +392,51 @@ pub async fn download_runtime_for_project(project_path: &AbsolutePath) -> Result
     tracing::info!("Resolved Node.js version: {version}");
     let runtime = download_runtime(JsRuntimeType::Node, &version).await?;
 
-    // Write resolved version to .node-version (if resolution occurred)
-    if should_write_back {
-        if let Err(e) = write_node_version_file(project_path, &version).await {
-            tracing::warn!("Failed to write .node-version: {e}");
-        } else {
-            tracing::info!("Using Node {version} - saved version to .node-version");
-        }
-    }
-
     Ok(runtime)
 }
 
 /// Resolve version requirement to an exact version.
 ///
-/// Returns (resolved_version, should_write_back).
+/// Returns the resolved exact version string.
 async fn resolve_version_for_project(
     version_req: &str,
-    _source: Option<VersionSource>,
     provider: &NodeProvider,
     cache_dir: &AbsolutePath,
-) -> Result<(Str, bool), Error> {
+) -> Result<Str, Error> {
     if version_req.is_empty() {
         // No source specified - fetch latest LTS from network
         tracing::debug!("No version source specified, fetching latest LTS from network");
-        let version = provider.resolve_latest_version().await?;
-        return Ok((version, true));
+        return provider.resolve_latest_version().await;
     }
 
     // Handle LTS aliases (lts/*, lts/iron, lts/-1)
     if NodeProvider::is_lts_alias(version_req) {
         tracing::debug!("Resolving LTS alias: {version_req}");
-        let version = provider.resolve_lts_alias(version_req).await?;
-        // Don't write back - user explicitly specified an LTS alias
-        return Ok((version, false));
+        return provider.resolve_lts_alias(version_req).await;
     }
 
     // Handle "latest" alias - resolves to absolute latest version (including non-LTS)
     if NodeProvider::is_latest_alias(version_req) {
         tracing::debug!("Resolving 'latest' alias");
-        let version = provider.resolve_version("*").await?;
-        // Don't write back - user explicitly specified "latest"
-        return Ok((version, false));
+        return provider.resolve_version("*").await;
     }
 
     // Check if it's an exact version
     if NodeProvider::is_exact_version(version_req) {
         let normalized = version_req.strip_prefix('v').unwrap_or(version_req);
         tracing::debug!("Using exact version: {normalized}");
-        // Never write back exact versions - user explicitly specified the version
-        return Ok((normalized.into(), false));
+        return Ok(normalized.into());
     }
 
     // Check local cache first
     if let Some(cached) = provider.find_cached_version(version_req, cache_dir).await? {
         tracing::debug!("Found cached version {cached} satisfying {version_req}");
-        // Don't write back - user specified a version requirement
-        return Ok((cached, false));
+        return Ok(cached);
     }
 
     // Resolve from network
     tracing::debug!("Resolving version requirement from network: {version_req}");
-    let version = provider.resolve_version(version_req).await?;
-
-    // Don't write back - user specified a version requirement
-    Ok((version, false))
+    provider.resolve_version(version_req).await
 }
 
 /// Check if the resolved version is compatible with lower priority sources.
@@ -512,34 +491,44 @@ fn check_constraint(
     }
 }
 
-/// Normalize and validate a version string as semver (exact version or range) or LTS alias.
-/// Trims whitespace and returns the normalized version, or None with a warning if invalid.
-pub fn normalize_version(version: &Str, source: &str) -> Option<Str> {
-    // Trim leading/trailing whitespace
-    let trimmed: Str = version.trim().into();
+/// Check if a version string is valid (exact version, range, or LTS alias).
+/// Trims whitespace before checking. Does not print warnings.
+#[must_use]
+pub fn is_valid_version(version: &str) -> bool {
+    let trimmed = version.trim();
 
     if trimmed.is_empty() {
-        return None;
+        return false;
     }
 
     // Accept version aliases (lts/*, lts/iron, lts/-1, latest)
-    if NodeProvider::is_version_alias(&trimmed) {
-        return Some(trimmed);
+    if NodeProvider::is_version_alias(trimmed) {
+        return true;
     }
 
     // Try parsing as exact version (strip 'v' prefix for exact version check)
-    let without_v = trimmed.strip_prefix('v').unwrap_or(&trimmed);
+    let without_v = trimmed.strip_prefix('v').unwrap_or(trimmed);
     if Version::parse(without_v).is_ok() {
-        return Some(trimmed);
+        return true;
     }
 
     // Try parsing as range
-    if Range::parse(&trimmed).is_ok() {
+    Range::parse(trimmed).is_ok()
+}
+
+/// Normalize and validate a version string as semver (exact version or range) or LTS alias.
+/// Trims whitespace and returns the normalized version, or None with a warning if invalid.
+pub fn normalize_version(version: &Str, source: &str) -> Option<Str> {
+    let trimmed: Str = version.trim().into();
+
+    if is_valid_version(&trimmed) {
         return Some(trimmed);
     }
 
-    // Invalid version
-    println!("warning: invalid version '{version}' in {source}, ignoring");
+    // Invalid version — print warning (only if non-empty, empty is just "not specified")
+    if !trimmed.is_empty() {
+        println!("warning: invalid version '{version}' in {source}, ignoring");
+    }
     None
 }
 
@@ -684,7 +673,7 @@ mod tests {
     }
 
     #[tokio::test]
-    async fn test_download_runtime_for_project_writes_back_when_no_version() {
+    async fn test_download_runtime_for_project_does_not_write_back_when_no_version() {
         let temp_dir = TempDir::new().unwrap();
         let temp_path = AbsolutePathBuf::new(temp_dir.path().to_path_buf()).unwrap();
 
@@ -700,16 +689,13 @@ mod tests {
 "#;
         tokio::fs::write(temp_path.join("package.json"), package_json).await.unwrap();
 
-        let runtime = download_runtime_for_project(&temp_path).await.unwrap();
-        let version = runtime.version();
+        let _runtime = download_runtime_for_project(&temp_path).await.unwrap();
 
-        // .node-version is written only if no ancestor has one (write-back is
-        // suppressed when an ancestor .node-version exists, e.g. in a monorepo)
-        if tokio::fs::try_exists(temp_path.join(".node-version")).await.unwrap() {
-            let node_version_content =
-                tokio::fs::read_to_string(temp_path.join(".node-version")).await.unwrap();
-            assert_eq!(node_version_content, format!("{version}\n"));
-        }
+        // .node-version should NOT be written (auto-write was removed)
+        assert!(
+            !tokio::fs::try_exists(temp_path.join(".node-version")).await.unwrap(),
+            ".node-version should not be auto-created"
+        );
 
         // package.json should remain unchanged
         let pkg_content = tokio::fs::read_to_string(temp_path.join("package.json")).await.unwrap();
@@ -777,6 +763,12 @@ mod tests {
 
         // Should download latest Node.js
         assert_eq!(runtime.runtime_type(), JsRuntimeType::Node);
+
+        // Should NOT write .node-version
+        assert!(
+            !tokio::fs::try_exists(temp_path.join(".node-version")).await.unwrap(),
+            ".node-version should not be auto-created"
+        );
     }
 
     #[tokio::test]
diff --git a/packages/cli/snap-tests-global/command-pack-npm10-with-workspace/snap.txt b/packages/cli/snap-tests-global/command-pack-npm10-with-workspace/snap.txt
index dcd99a5eff..461f800722 100644
--- a/packages/cli/snap-tests-global/command-pack-npm10-with-workspace/snap.txt
+++ b/packages/cli/snap-tests-global/command-pack-npm10-with-workspace/snap.txt
@@ -10,11 +10,6 @@
     "integrity": "sha512-<hash>",
     "filename": "command-pack-npm10-with-workspace-1.0.0.tgz",
     "files": [
-      {
-        "path": ".node-version",
-        "size": <variable>,
-        "mode": 420
-      },
       {
         "path": "output.log",
         "size": <variable>,
@@ -46,7 +41,7 @@
         "mode": 420
       }
     ],
-    "entryCount": 7,
+    "entryCount": 6,
     "bundled": []
   }
 ]
@@ -170,11 +165,6 @@
     "integrity": "sha512-<hash>",
     "filename": "command-pack-npm10-with-workspace-1.0.0.tgz",
     "files": [
-      {
-        "path": ".node-version",
-        "size": <variable>,
-        "mode": 420
-      },
       {
         "path": "app-1.0.0.tgz",
         "size": <variable>,
@@ -221,7 +211,7 @@
         "mode": 420
       }
     ],
-    "entryCount": 10,
+    "entryCount": 9,
     "bundled": []
   }
 ]
diff --git a/packages/cli/snap-tests-global/command-pack-npm10/snap.txt b/packages/cli/snap-tests-global/command-pack-npm10/snap.txt
index d4efce7401..1835d19aae 100644
--- a/packages/cli/snap-tests-global/command-pack-npm10/snap.txt
+++ b/packages/cli/snap-tests-global/command-pack-npm10/snap.txt
@@ -10,11 +10,6 @@
     "integrity": "sha512-<hash>",
     "filename": "command-pack-npm10-1.0.0.tgz",
     "files": [
-      {
-        "path": ".node-version",
-        "size": <variable>,
-        "mode": 420
-      },
       {
         "path": "output.log",
         "size": <variable>,
@@ -36,7 +31,7 @@
         "mode": 420
       }
     ],
-    "entryCount": 5,
+    "entryCount": 4,
     "bundled": []
   }
 ]
@@ -53,11 +48,6 @@
     "integrity": "sha512-<hash>",
     "filename": "command-pack-npm10-1.0.0.tgz",
     "files": [
-      {
-        "path": ".node-version",
-        "size": <variable>,
-        "mode": 420
-      },
       {
         "path": "command-pack-npm10-1.0.0.tgz",
         "size": <variable>,
@@ -84,7 +74,7 @@
         "mode": 420
       }
     ],
-    "entryCount": 6,
+    "entryCount": 5,
     "bundled": []
   }
 ]
@@ -101,11 +91,6 @@
     "integrity": "sha512-<hash>",
     "filename": "command-pack-npm10-1.0.0.tgz",
     "files": [
-      {
-        "path": ".node-version",
-        "size": <variable>,
-        "mode": 420
-      },
       {
         "path": "command-pack-npm10-1.0.0.tgz",
         "size": <variable>,
@@ -132,7 +117,7 @@
         "mode": 420
       }
     ],
-    "entryCount": 6,
+    "entryCount": 5,
     "bundled": []
   }
 ]
diff --git a/packages/cli/snap-tests-global/command-pack-pnpm10-with-workspace/snap.txt b/packages/cli/snap-tests-global/command-pack-pnpm10-with-workspace/snap.txt
index cb858c8d43..c7817703ac 100644
--- a/packages/cli/snap-tests-global/command-pack-pnpm10-with-workspace/snap.txt
+++ b/packages/cli/snap-tests-global/command-pack-pnpm10-with-workspace/snap.txt
@@ -1,7 +1,6 @@
 > vp pm pack && rm -rf *.tgz # should pack current workspace root
 📦  command-pack-pnpm10-with-workspace@<semver>
 Tarball Contents
-.node-version
 output.log
 package.json
 packages/app/package.json
@@ -39,9 +38,6 @@ command-pack-pnpm10-with-workspace-1.0.0.tgz
     "version": "1.0.0",
     "filename": "command-pack-pnpm10-with-workspace-1.0.0.tgz",
     "files": [
-      {
-        "path": ".node-version"
-      },
       {
         "path": "command-pack-pnpm10-with-workspace-1.0.0.tgz"
       },
@@ -107,7 +103,6 @@ Tarball Details
 > vp pm pack --out ./dist/package.tgz && rm -rf ./dist # should pack with output file
 📦  command-pack-pnpm10-with-workspace@<semver>
 Tarball Contents
-.node-version
 app-1.0.0.tgz
 command-pack-pnpm10-with-workspace-1.0.0.tgz
 out.json
@@ -125,7 +120,6 @@ Tarball Details
 > vp pm pack --pack-destination ./dist && rm -rf ./dist # should pack with destination
 📦  command-pack-pnpm10-with-workspace@<semver>
 Tarball Contents
-.node-version
 app-1.0.0.tgz
 command-pack-pnpm10-with-workspace-1.0.0.tgz
 out.json
@@ -143,7 +137,6 @@ Tarball Details
 > vp pm pack --pack-gzip-level 9 && rm -rf *.tgz # should pack with gzip compression level
 📦  command-pack-pnpm10-with-workspace@<semver>
 Tarball Contents
-.node-version
 app-1.0.0.tgz
 command-pack-pnpm10-with-workspace-1.0.0.tgz
 out.json
@@ -164,9 +157,6 @@ command-pack-pnpm10-with-workspace-1.0.0.tgz
   "version": "1.0.0",
   "filename": "foo-command-pack-pnpm10-with-workspace-1.0.0.tgz",
   "files": [
-    {
-      "path": ".node-version"
-    },
     {
       "path": "app-1.0.0.tgz"
     },
diff --git a/packages/cli/snap-tests-global/command-pack-pnpm10/snap.txt b/packages/cli/snap-tests-global/command-pack-pnpm10/snap.txt
index ccdfcc03d9..ecfb9b7e5f 100644
--- a/packages/cli/snap-tests-global/command-pack-pnpm10/snap.txt
+++ b/packages/cli/snap-tests-global/command-pack-pnpm10/snap.txt
@@ -18,7 +18,6 @@ Options:
 > vp pm pack && rm -rf *.tgz # should pack current package
 📦  command-pack-pnpm10@<semver>
 Tarball Contents
-.node-version
 output.log
 package.json
 snap.txt
@@ -29,7 +28,6 @@ command-pack-pnpm10-1.0.0.tgz
 > vp pm pack --out ./dist/package.tgz && rm -rf ./dist # should pack with output file
 📦  command-pack-pnpm10@<semver>
 Tarball Contents
-.node-version
 command-pack-pnpm10-1.0.0.tgz
 output.log
 package.json
@@ -41,7 +39,6 @@ Tarball Details
 > vp pm pack --pack-destination ./dist && rm -rf ./dist # should pack with destination
 📦  command-pack-pnpm10@<semver>
 Tarball Contents
-.node-version
 command-pack-pnpm10-1.0.0.tgz
 output.log
 package.json
@@ -56,9 +53,6 @@ Tarball Details
   "version": "1.0.0",
   "filename": "command-pack-pnpm10-1.0.0.tgz",
   "files": [
-    {
-      "path": ".node-version"
-    },
     {
       "path": "command-pack-pnpm10-1.0.0.tgz"
     },
@@ -83,9 +77,6 @@ Tarball Details
   "version": "1.0.0",
   "filename": "command-pack-pnpm10-1.0.0.tgz",
   "files": [
-    {
-      "path": ".node-version"
-    },
     {
       "path": "command-pack-pnpm10-1.0.0.tgz"
     },
@@ -107,7 +98,6 @@ Tarball Details
 > vp pm pack -- --loglevel=warn && rm -rf *.tgz # should support pass through arguments
 📦  command-pack-pnpm10@<semver>
 Tarball Contents
-.node-version
 command-pack-pnpm10-1.0.0.tgz
 output.log
 package.json
diff --git a/packages/cli/snap-tests-global/command-pack-yarn4-with-workspace/snap.txt b/packages/cli/snap-tests-global/command-pack-yarn4-with-workspace/snap.txt
index aa7e4e1ea2..49e144a7fd 100644
--- a/packages/cli/snap-tests-global/command-pack-yarn4-with-workspace/snap.txt
+++ b/packages/cli/snap-tests-global/command-pack-yarn4-with-workspace/snap.txt
@@ -10,7 +10,6 @@
 ➤ YN0000: · Done with warnings in <variable>ms <variable>ms
 
 > vp pm pack # should pack current workspace root
-➤ YN0000: .node-version
 ➤ YN0000: output.log
 ➤ YN0000: package.json
 ➤ YN0000: snap.txt
@@ -19,7 +18,6 @@
 ➤ YN0000: Done in <variable>ms <variable>ms
 
 > vp pm pack --recursive # should pack all packages in workspace (uses workspaces foreach --all pack)
-➤ YN0000: .node-version
 ➤ YN0000: output.log
 ➤ YN0000: package.json
 ➤ YN0000: snap.txt
@@ -50,7 +48,6 @@ Done in <variable>ms <variable>ms
 Done in <variable>ms <variable>ms
 
 > vp pm pack --out ./dist/package.tgz # should pack with output file
-➤ YN0000: .node-version
 ➤ YN0000: output.log
 ➤ YN0000: package.json
 ➤ YN0000: snap.txt
@@ -60,7 +57,6 @@ Done in <variable>ms <variable>ms
 
 > vp pm pack --json # should pack with json output
 {"base":"<cwd>"}
-{"location":".node-version"}
 {"location":"dist/package.tgz"}
 {"location":"output.log"}
 {"location":"package.json"}
diff --git a/packages/cli/snap-tests-global/command-pack-yarn4/snap.txt b/packages/cli/snap-tests-global/command-pack-yarn4/snap.txt
index 4c022f9291..ba931513ab 100644
--- a/packages/cli/snap-tests-global/command-pack-yarn4/snap.txt
+++ b/packages/cli/snap-tests-global/command-pack-yarn4/snap.txt
@@ -1,5 +1,4 @@
 > vp pm pack # should pack current package
-➤ YN0000: .node-version
 ➤ YN0000: output.log
 ➤ YN0000: package.json
 ➤ YN0000: snap.txt
@@ -8,7 +7,6 @@
 ➤ YN0000: Done in <variable>ms <variable>ms
 
 > vp pm pack --out ./dist/package.tgz # should pack with output file
-➤ YN0000: .node-version
 ➤ YN0000: output.log
 ➤ YN0000: package.json
 ➤ YN0000: snap.txt
@@ -18,7 +16,6 @@
 
 > vp pm pack --json # should pack with json output
 {"base":"<cwd>"}
-{"location":".node-version"}
 {"location":"dist/package.tgz"}
 {"location":"output.log"}
 {"location":"package.json"}
@@ -27,7 +24,6 @@
 {"output":"<cwd>/package.tgz"}
 
 > vp pm pack -- --dry-run # should support pass through arguments
-➤ YN0000: .node-version
 ➤ YN0000: dist/package.tgz
 ➤ YN0000: output.log
 ➤ YN0000: package.json
diff --git a/packages/cli/snap-tests-global/delegate-respects-default-node-version/package.json b/packages/cli/snap-tests-global/delegate-respects-default-node-version/package.json
new file mode 100644
index 0000000000..545d0359ca
--- /dev/null
+++ b/packages/cli/snap-tests-global/delegate-respects-default-node-version/package.json
@@ -0,0 +1,8 @@
+{
+  "name": "delegate-respects-default-node-version",
+  "version": "1.0.0",
+  "private": true,
+  "scripts": {
+    "check-node": "node -e \"console.log(process.version)\""
+  }
+}
diff --git a/packages/cli/snap-tests-global/delegate-respects-default-node-version/snap.txt b/packages/cli/snap-tests-global/delegate-respects-default-node-version/snap.txt
new file mode 100644
index 0000000000..5d3658f839
--- /dev/null
+++ b/packages/cli/snap-tests-global/delegate-respects-default-node-version/snap.txt
@@ -0,0 +1,17 @@
+> vp env default 22.12.0 # Set global default to 22.12.0
+✓ Default Node.js version set to <semver>
+
+> vp run check-node # Should also use 22.12.0
+
+> delegate-respects-default-node-version@<semver> check-node <cwd>
+> node -e "console.log(process.version)"
+
+v<semver>
+
+> vp exec node -e "console.log(process.version)" # Should also use 22.12.0
+v22.12.0
+
+> vp env which node # Should show 22.12.0 from 'default' source
+<vite-plus-home>/js_runtime/node/<semver>/bin/node
+  Version:    22.12.0
+  Source:     <vite-plus-home>/config.json
diff --git a/packages/cli/snap-tests-global/delegate-respects-default-node-version/steps.json b/packages/cli/snap-tests-global/delegate-respects-default-node-version/steps.json
new file mode 100644
index 0000000000..19db8e8903
--- /dev/null
+++ b/packages/cli/snap-tests-global/delegate-respects-default-node-version/steps.json
@@ -0,0 +1,11 @@
+{
+  "serial": true,
+  "ignoredPlatforms": ["win32"],
+  "commands": [
+    "vp env default 22.12.0 # Set global default to 22.12.0",
+    "vp run check-node # Should also use 22.12.0",
+    "vp exec node -e \"console.log(process.version)\" # Should also use 22.12.0",
+    "vp env which node # Should show 22.12.0 from 'default' source"
+  ],
+  "after": ["vp env default lts # Restore default to LTS"]
+}
diff --git a/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/package.json b/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/package.json
new file mode 100644
index 0000000000..e77e0c4fe8
--- /dev/null
+++ b/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/package.json
@@ -0,0 +1,8 @@
+{
+  "name": "fallback-all-invalid-to-user-default",
+  "version": "1.0.0",
+  "private": true,
+  "engines": {
+    "node": "invalid"
+  }
+}
diff --git a/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/snap.txt b/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/snap.txt
new file mode 100644
index 0000000000..3b9822ebcd
--- /dev/null
+++ b/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/snap.txt
@@ -0,0 +1,6 @@
+> vp env default 22.12.0 # Set user default
+✓ Default Node.js version set to <semver>
+
+> vp exec node -e "console.log(process.version)" # Should use default 22.12.0, not LTS
+warning: invalid version 'invalid' in engines.node, ignoring
+v<semver>
diff --git a/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/steps.json b/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/steps.json
new file mode 100644
index 0000000000..5401c467a5
--- /dev/null
+++ b/packages/cli/snap-tests-global/fallback-all-invalid-to-user-default/steps.json
@@ -0,0 +1,9 @@
+{
+  "serial": true,
+  "ignoredPlatforms": ["win32"],
+  "commands": [
+    "vp env default 22.12.0 # Set user default",
+    "vp exec node -e \"console.log(process.version)\" # Should use default 22.12.0, not LTS"
+  ],
+  "after": ["vp env default lts # Restore default"]
+}
diff --git a/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/package.json b/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/package.json
new file mode 100644
index 0000000000..dc1f13f7f9
--- /dev/null
+++ b/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "fallback-invalid-engines-to-dev-engines",
+  "version": "1.0.0",
+  "private": true,
+  "devEngines": {
+    "runtime": {
+      "name": "node",
+      "version": "22.12.0"
+    }
+  },
+  "engines": {
+    "node": "invalid"
+  }
+}
diff --git a/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/snap.txt b/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/snap.txt
new file mode 100644
index 0000000000..6ac44ac490
--- /dev/null
+++ b/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/snap.txt
@@ -0,0 +1,10 @@
+> vp exec node -e "console.log(process.version)" # Should use devEngines.runtime 22.12.0, not LTS
+warning: invalid version 'invalid' in engines.node, ignoring
+warning: invalid version 'invalid' in engines.node, ignoring
+v<semver>
+
+> vp env which node # Should show devEngines.runtime source
+warning: invalid version 'invalid' in engines.node, ignoring
+<vite-plus-home>/js_runtime/node/<semver>/bin/node
+  Version:    22.12.0
+  Source:     <cwd>/package.json
diff --git a/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/steps.json b/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/steps.json
new file mode 100644
index 0000000000..e9d33e4e04
--- /dev/null
+++ b/packages/cli/snap-tests-global/fallback-invalid-engines-to-dev-engines/steps.json
@@ -0,0 +1,7 @@
+{
+  "ignoredPlatforms": ["win32"],
+  "commands": [
+    "vp exec node -e \"console.log(process.version)\" # Should use devEngines.runtime 22.12.0, not LTS",
+    "vp env which node # Should show devEngines.runtime source"
+  ]
+}
diff --git a/packages/tools/src/snap-test.ts b/packages/tools/src/snap-test.ts
index e581d0bbe2..2d02eecd75 100755
--- a/packages/tools/src/snap-test.ts
+++ b/packages/tools/src/snap-test.ts
@@ -125,7 +125,8 @@ export async function snapTest() {
 
   const casesDir = path.resolve(values.dir || 'snap-tests');
 
-  const taskFunctions: (() => Promise<void>)[] = [];
+  const serialTasks: (() => Promise<void>)[] = [];
+  const parallelTasks: (() => Promise<void>)[] = [];
   const missingStepsJson: string[] = [];
   for (const caseName of fs.readdirSync(casesDir)) {
     if (caseName.startsWith('.')) {
@@ -135,12 +136,19 @@ export async function snapTest() {
     if (!fs.statSync(caseDir).isDirectory()) {
       continue;
     }
-    if (!fs.existsSync(path.join(caseDir, 'steps.json'))) {
+    const stepsPath = path.join(caseDir, 'steps.json');
+    if (!fs.existsSync(stepsPath)) {
       missingStepsJson.push(caseName);
       continue;
     }
     if (caseName.includes(filter)) {
-      taskFunctions.push(() => runTestCase(caseName, tempTmpDir, casesDir, values['bin-dir']));
+      const steps: Steps = JSON.parse(readFileSync(stepsPath, 'utf-8'));
+      const task = () => runTestCase(caseName, tempTmpDir, casesDir, values['bin-dir']);
+      if (steps.serial) {
+        serialTasks.push(task);
+      } else {
+        parallelTasks.push(task);
+      }
     }
   }
 
@@ -150,14 +158,18 @@ export async function snapTest() {
     );
   }
 
-  if (taskFunctions.length > 0) {
+  const totalCount = serialTasks.length + parallelTasks.length;
+  if (totalCount > 0) {
     const cpuCount = cpus().length;
     console.log(
-      'Running %d test cases with concurrency limit of %d (CPU count)',
-      taskFunctions.length,
+      'Running %d test cases (%d serial + %d parallel, concurrency limit %d)',
+      totalCount,
+      serialTasks.length,
+      parallelTasks.length,
       cpuCount,
     );
-    await runWithConcurrencyLimit(taskFunctions, cpuCount);
+    await runWithConcurrencyLimit(serialTasks, 1);
+    await runWithConcurrencyLimit(parallelTasks, cpuCount);
   }
   process.exit(0); // Ensure exit even if there are pending timed-out steps
 }
@@ -186,6 +198,11 @@ interface Steps {
    * These commands are not included in the snap output.
    */
   after?: string[];
+  /**
+   * If true, this test case will run serially before parallel tests.
+   * Use for tests that modify global shared state (e.g., `vp env default`).
+   */
+  serial?: boolean;
 }
 
 async function runTestCase(name: string, tempTmpDir: string, casesDir: string, binDir?: string) {
diff --git a/rfcs/js-runtime.md b/rfcs/js-runtime.md
index e30ec95921..08629511a2 100644
--- a/rfcs/js-runtime.md
+++ b/rfcs/js-runtime.md
@@ -157,7 +157,6 @@ pub async fn download_runtime(
 /// Download runtime based on project's version configuration
 /// Reads from .node-version, engines.node, or devEngines.runtime (in priority order)
 /// Resolves semver ranges, downloads the matching version
-/// Writes resolved version to .node-version for future use
 pub async fn download_runtime_for_project(
     project_path: &AbsolutePath,
 ) -> Result<JsRuntime, Error>;
@@ -209,7 +208,6 @@ use vite_path::AbsolutePathBuf;
 let project_path = AbsolutePathBuf::new("/path/to/project".into()).unwrap();
 let runtime = download_runtime_for_project(&project_path).await?;
 // Version is resolved from .node-version > engines.node > devEngines.runtime
-// Resolved version is saved to .node-version for future use
 ```
 
 ## Cache Directory Structure
@@ -407,52 +405,13 @@ When no version source exists:
 1. Check local cache for installed Node.js versions
 2. Use the **latest installed version** (if any exist)
 3. If no cached versions exist, fetch and use latest LTS from network
-4. Write the used version to `.node-version`
-5. Print: `Using Node {version} - saved version to .node-version`
 
 This optimizes for:
 
 - Avoiding unnecessary network requests
 - Using what the user already has installed
-- Establishing `.node-version` as the version source going forward
 
-### Version Write-Back
-
-When `download_runtime_for_project` resolves a version and **no version source exists**, it writes the resolved version to `.node-version`. This establishes a version source for future use.
-
-**Write-back only occurs when no version source exists:**
-
-| Read From            | Write To               | Message                                                 |
-| -------------------- | ---------------------- | ------------------------------------------------------- |
-| `.node-version`      | No write               | -                                                       |
-| `engines.node`       | No write               | -                                                       |
-| `devEngines.runtime` | No write               | -                                                       |
-| No source            | Create `.node-version` | "Using Node {version} - saved version to .node-version" |
-
-**Key behaviors:**
-
-1. Only write when no version source exists (respects user's explicit version requirements)
-2. Use three-part version without `v` prefix with Unix line ending
-3. Print informational message when saving version
-
-**Example: Before download (no version source)**
-
-Project structure:
-
-```
-my-project/
-└── package.json
-```
-
-**After download (.node-version created)**
-
-Project structure:
-
-```
-my-project/
-├── .node-version   # Contains: 24.5.0
-└── package.json
-```
+**Note:** `.node-version` is only written explicitly via `vp env pin`.
 
 ## Download Sources
 
@@ -723,7 +682,7 @@ pub enum Error {
 9. ✅ Support semver ranges (^, ~, etc.) with version resolution
 10. ✅ Version index caching with 1-hour TTL
 11. ✅ Support both single runtime and array of runtimes in devEngines
-12. ✅ Write resolved version to `.node-version` file
+12. ~~Write resolved version to `.node-version` file~~ (removed — `.node-version` is only written by `vp env pin`)
 13. ✅ Optimized version resolution (skip network for exact versions, check local cache for ranges)
 14. ✅ Multi-source version reading with priority: `.node-version` > `engines.node` > `devEngines.runtime`
 15. ✅ Support `.node-version` file format (with/without v prefix, partial versions)