@@ -62,6 +62,14 @@ Use the shared primitives under [`src/ci/`](src/ci/) for portable runtime behavi
 - GitLab: edit the TypeScript runtime under [`src/gitlab/`](src/gitlab/). The template downloads and runs the `vp pack` bundle at `dist/gitlab/index.mjs`. See the [GitLab integration notes](rfcs/gitlab-integration.md) for design constraints and follow-up work.
 - Azure Pipelines: edit the runtime under [`src/azure/`](src/azure/). Azure cannot execute the GitHub Action bundle; the template runs `dist/azure/index.mjs` in `prepare` and `finalize` phases around `Cache@2`. See the [Azure integration notes](rfcs/azure-pipelines-integration.md) for the design, parity table, and cache semantics.
 
+### Installer Node Selection
+
+All three integrations run the installer from the configured project directory. setup-vp selects the Node version: `node-version` takes precedence over `node-version-file`, followed by automatic project discovery. Discovery checks `.node-version`, `package.json#devEngines.runtime`, `package.json#engines.node`, and `.nvmrc` in each directory before checking its parent. It passes the selected value through `VP_SETUP_NODE_VERSION`. With no selection or with `node-manager: false`, it clears the override so the installer keeps its LTS default.
+
+Installers that support this protocol resolve an explicit environment override once and reuse that Node version when it satisfies both the CLI and the pinned pnpm requirements. Otherwise, they use a separate LTS runtime for installation. The installer itself does not discover project pins or apply normal Node session or user defaults. For an override, it writes the exact requested version to the temporary path in `VP_SETUP_NODE_VERSION_FILE`; this remains the requested version even when installation needs a fallback. For an explicit input, setup-vp uses that result for `vp env use`. Automatic discovery retains its normal directory scope.
+
+The temporary result is cleared before each installer attempt and removed after installation. Older installers do not write a result, so setup-vp retains the original selector and existing behavior. Updating setup-vp alone does not enable runtime reuse for an older Vite+ release.
+
 ## GitLab End-to-End Tests
 
 Use the dedicated [GitLab test project](https://gitlab.com/fengmk2/setup-vp-gitlab-test) to test the remote integration. The [GitLab E2E workflow](.github/workflows/gitlab-e2e.yml) accepts `run-e2e` label requests for same-repository PRs and manual `workflow_dispatch` requests on `main`. The job uses the GitLab trigger secret without checking out or executing PR files on the GitHub runner.
 
@@ -353,6 +353,8 @@ When `working-directory` is set, relative `run-install.cwd`, `node-version-file`
 
 Omitting both `node-version` and `node-version-file` leaves the session without an override. With the Vite+ Node.js manager enabled, its shims search the current directory and its parents for `.node-version`, `package.json#devEngines.runtime`, `package.json#engines.node`, and `.nvmrc`, in that order. If the project does not declare a version, Vite+ uses the user-level default. Set this default with `vp env default <version>`. If no user-level default exists, Vite+ uses the latest LTS release.
 
+For Vite+ releases that support an installer Node override, setup-vp also reads these project declarations before installation. It passes the selected version to the installer to avoid a second Node download when that version supports both the CLI and its installation dependencies. Without a selection, or when that version is incompatible, installation uses LTS. Older Vite+ installers retain their existing behavior.
+
 `working-directory` applies to the action. Each later workflow step keeps its own working directory. Vite+ searches for Node.js version sources from each command's current working directory. For a subproject, set `working-directory` on the step that runs `node` or `vp`.
 
 `node-manager: false` runs `vp env off node` (Vite+ 0.3.1+; `vp env off` on older versions), so `vp` commands prefer the Node.js already on `PATH`. It cannot be combined with `node-version` or `node-version-file`.
 
@@ -17,12 +17,14 @@
     "@actions/core": "^3.0.0",
     "@actions/exec": "^3.0.0",
     "@actions/glob": "^0.7.0",
+    "semver": "^7.8.5",
     "yaml": "^2.8.2",
     "zod": "^4.0.0"
   },
   "devDependencies": {
     "@e18e/eslint-plugin": "^0.8.1",
     "@types/node": "^24.0.0",
+    "@types/semver": "^7.8.0",
     "fallow": "3.33.1",
     "typescript": "^7.0.0",
     "vite": "catalog:",
 
@@ -2,6 +2,40 @@ import { describe, expect, it, vi } from "vite-plus/test";
 import { runFinalize, runPrepare } from "./index.js";
 
 describe("Azure lifecycle", () => {
+  it("passes the Node selector to bootstrap and activates its exact result", async () => {
+    const run = vi.fn();
+    const installVitePlus = vi.fn(async () => "22.23.1");
+    await runPrepare(
+      {
+        SETUP_VP_VERSION: "1.3.0",
+        SETUP_VP_NODE_VERSION: "22",
+        SYSTEM_DEFAULTWORKINGDIRECTORY: process.cwd(),
+      },
+      {
+        installVitePlus,
+        prepareCacheMetadata: () => ({ ready: false }),
+        configureAuth: () => undefined,
+        setupSfw: async () => ({ executable: "vp", sfw: false }),
+        parseRunInstall: () => [],
+        runInstall: () => undefined,
+        getCommandOutput: () => "vp v1.3.0",
+        run,
+        parseInstalledVpVersion: () => "1.3.0",
+        prependPath: () => undefined,
+        setVariable: () => undefined,
+        logWarning: () => undefined,
+        logInfo: () => undefined,
+      },
+    );
+    expect(installVitePlus).toHaveBeenCalledWith(
+      "1.3.0",
+      expect.objectContaining({
+        projectDir: process.cwd(),
+        nodeVersion: "22",
+      }),
+    );
+    expect(run).toHaveBeenCalledWith("vp", ["env", "use", "22.23.1"], { cwd: process.cwd() });
+  });
   it("runs prepare in install → cache order", async () => {
     const calls: string[] = [];
     await runPrepare(
 
@@ -76,27 +76,24 @@ export async function runPrepare(
     warning: ports.logWarning,
   };
   const version = createVersionResolver(context).resolveVitePlusVersion(inputs, projectDir);
-  const nodeVersion =
-    inputs.nodeVersion ||
-    (inputs.nodeVersionFile
-      ? createNodeVersionResolver(context).resolveNodeVersionFile(
-          inputs.nodeVersionFile,
-          projectDir,
-        )
-      : undefined);
+  let nodeVersion = createNodeVersionResolver(context).resolveNodeVersionInput(inputs, projectDir);
 
   ports.setVariable("SETUP_VP_CACHE_HIT", "false");
   ports.setVariable("SETUP_VP_CACHE_READY", "false");
   ports.setVariable("SETUP_VP_SFW_READY", "false");
   // Keep the setup runtime independent of the project's selected Node version.
   ports.setVariable("SETUP_VP_BOOTSTRAP_NODE", process.execPath);
 
-  await ports.installVitePlus(version, {
-    env,
-    prependPath: (binDir) => ports.prependPath(binDir),
-    exportPath: (value) => ports.setVariable("PATH", value),
-    logWarningFn: ports.logWarning,
-  });
+  nodeVersion =
+    (await ports.installVitePlus(version, {
+      env,
+      projectDir,
+      nodeVersion,
+      nodeManager: inputs.nodeManager,
+      prependPath: (binDir) => ports.prependPath(binDir),
+      exportPath: (value) => ports.setVariable("PATH", value),
+      logWarningFn: ports.logWarning,
+    })) ?? nodeVersion;
   // Finalize must use the resolved version, including pins from files or lockfiles.
   ports.setVariable("SETUP_VP_RESOLVED_VERSION", version);
 
 
@@ -40,8 +40,9 @@ function fixture() {
 }
 
 describe("Azure parity", () => {
-  it("exports the full installer PATH for subsequent Azure tasks", async () => {
-    const { root, env, ports } = fixture();
+  it("exports the installer PATH and passes project Node discovery without a session override", async () => {
+    const { root, project, env, ports } = fixture();
+    writeFileSync(path.join(project, ".node-version"), "22.18.0");
     const bin = path.join(root, "bin");
     const data = path.join(root, "data");
     const fallbackBin = path.join(data, "fallback-bin");
@@ -50,6 +51,8 @@ describe("Azure parity", () => {
       installVitePlus(version, {
         ...options,
         runInstall: (_url, installEnv) => {
+          expect(installEnv.VP_SETUP_NODE_VERSION).toBe("22.18.0");
+          writeFileSync(installEnv.VP_SETUP_NODE_VERSION_FILE!, "22.18.0");
           writeFileSync(
             installEnv.SETUP_VP_DIRS_FILE!,
             `data\t${data}\nbin\t${bin}\ncache\t/cache\nconfig\t/config\nstate\t/state\n`,
@@ -62,6 +65,7 @@ describe("Azure parity", () => {
     await runPrepare({ ...env, PATH: "/system/bin", SETUP_VP_VERSION: "latest" }, ports);
 
     expect(ports.prependPath).toHaveBeenCalledWith(bin);
+    expect(ports.run).not.toHaveBeenCalledWith("vp", ["env", "use", "22.18.0"], expect.anything());
     expect(ports.setVariable).toHaveBeenCalledWith(
       "PATH",
       [bin, "/system/bin", fallbackBin].join(path.delimiter),