diff --git a/.gitignore b/.gitignore
index 334f48a..be6c204 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ node_modules
 .claude
 dist
 *.vsix
+package-lock.json
diff --git a/README.md b/README.md
index 879d277..e43132f 100644
--- a/README.md
+++ b/README.md
@@ -105,3 +105,5 @@ These bridge tools let pi inspect selections, diagnostics, symbols, definitions,
 | Setting          | Default | Description                                             |
 | ---------------- | ------- | ------------------------------------------------------- |
 | `pi-vscode.path` | `""`    | Absolute path to the pi binary (auto-detected if empty) |
+
+On Windows, an extensionless `pi-vscode.path` is auto-probed for `.cmd`/`.exe`/`.ps1` variants so extensionless npm shims work out of the box.
diff --git a/src/_resolve.ts b/src/_resolve.ts
index 098b8a2..c4c76b8 100644
--- a/src/_resolve.ts
+++ b/src/_resolve.ts
@@ -1,6 +1,8 @@
 import { accessSync, constants } from "node:fs";
 import { join } from "node:path";
 
+const WIN_EXECUTABLE_EXTENSIONS = [".cmd", ".exe", ".ps1"];
+
 export interface ResolveOptions {
   /** User-configured custom path */
   customPath?: string;
@@ -10,6 +12,10 @@ export interface ResolveOptions {
   home?: string;
   /** PATH environment variable */
   pathEnv?: string;
+  /** %APPDATA% on Windows (defaults to process.env.APPDATA) */
+  appData?: string;
+  /** %LOCALAPPDATA% on Windows (defaults to process.env.LOCALAPPDATA) */
+  localAppData?: string;
   /** Workspace root directories */
   workspaceDirs?: string[];
   /** File access check (defaults to fs.accessSync) */
@@ -17,8 +23,6 @@ export interface ResolveOptions {
 }
 
 export function resolvePiBinary(opts: ResolveOptions = {}): string {
-  if (opts.customPath) return opts.customPath;
-
   const platform = opts.platform ?? process.platform;
   const home = opts.home ?? process.env.HOME ?? process.env.USERPROFILE ?? "";
   const pathEnv = opts.pathEnv ?? process.env.PATH ?? "";
@@ -27,10 +31,20 @@ export function resolvePiBinary(opts: ResolveOptions = {}): string {
 
   const isWin = platform === "win32";
   // On Windows, npm/pnpm create .cmd shims; also check .exe and .ps1
-  const names = isWin ? ["pi.cmd", "pi.exe", "pi.ps1"] : ["pi"];
+  const names = isWin ? WIN_EXECUTABLE_EXTENSIONS.map((ext) => `pi${ext}`) : ["pi"];
   // Windows lacks Unix-style execute permission; just check the file exists
   const accessFlag = isWin ? constants.F_OK : constants.X_OK;
 
+  // Extensionless npm shims on Windows are bash scripts that cannot be spawned;
+  // probe for .cmd/.exe/.ps1 variants when the custom path has no extension.
+  if (opts.customPath) {
+    if (isWin) {
+      const resolved = resolveWindowsExecutable(opts.customPath, access);
+      if (resolved) return resolved;
+    }
+    return opts.customPath;
+  }
+
   // Check workspace-local node_modules/.bin first (respects monorepos / multi-root)
   const workspaceCandidates = workspaceDirs.flatMap((dir) =>
     names.map((n) => join(dir, "node_modules", ".bin", n)),
@@ -38,7 +52,7 @@ export function resolvePiBinary(opts: ResolveOptions = {}): string {
 
   // Then well-known global paths
   const globalCandidates = isWin
-    ? []
+    ? windowsGlobalDirs(opts).flatMap((d) => names.map((n) => join(d, n)))
     : [`${home}/.bun/bin/pi`, `${home}/.local/bin/pi`, `${home}/.npm-global/bin/pi`];
 
   const candidates = [...workspaceCandidates, ...globalCandidates];
@@ -64,3 +78,29 @@ export function resolvePiBinary(opts: ResolveOptions = {}): string {
 
   return "pi";
 }
+
+function windowsGlobalDirs(opts: ResolveOptions): string[] {
+  const appData = opts.appData ?? process.env.APPDATA ?? "";
+  const localAppData = opts.localAppData ?? process.env.LOCALAPPDATA ?? "";
+  const dirs: string[] = [];
+  if (appData) dirs.push(join(appData, "npm"));
+  if (localAppData) dirs.push(join(localAppData, "pnpm"));
+  return dirs;
+}
+
+function resolveWindowsExecutable(
+  filePath: string,
+  access: (path: string, mode: number) => void,
+): string | null {
+  // If path already has any extension (dot after the last separator), leave it alone.
+  const sep = Math.max(filePath.lastIndexOf("\\"), filePath.lastIndexOf("/"));
+  if (filePath.lastIndexOf(".") > sep) return null;
+
+  for (const ext of WIN_EXECUTABLE_EXTENSIONS) {
+    try {
+      access(filePath + ext, constants.F_OK);
+      return filePath + ext;
+    } catch {}
+  }
+  return null;
+}
diff --git a/test/resolve.test.ts b/test/resolve.test.ts
index 9eaab7e..9010046 100644
--- a/test/resolve.test.ts
+++ b/test/resolve.test.ts
@@ -14,6 +14,68 @@ describe("resolvePiBinary", () => {
     expect(resolvePiBinary({ customPath: "/custom/pi" })).toBe("/custom/pi");
   });
 
+  it("resolves custom path to .cmd on windows when extensionless", () => {
+    const customPath = "C:\\nvm4w\\nodejs\\pi";
+    const cmdPath = "C:\\nvm4w\\nodejs\\pi.cmd";
+    const result = resolvePiBinary({
+      customPath,
+      platform: "win32",
+      access: mockAccess(new Set([cmdPath])),
+    });
+    expect(result).toBe(cmdPath);
+  });
+
+  it("resolves custom path to .exe on windows when .cmd absent", () => {
+    const customPath = "C:\\nvm4w\\nodejs\\pi";
+    const exePath = "C:\\nvm4w\\nodejs\\pi.exe";
+    const result = resolvePiBinary({
+      customPath,
+      platform: "win32",
+      access: mockAccess(new Set([exePath])),
+    });
+    expect(result).toBe(exePath);
+  });
+
+  it("returns custom path as-is on windows when it already has .cmd extension", () => {
+    const customPath = "C:\\nvm4w\\nodejs\\pi.cmd";
+    const result = resolvePiBinary({
+      customPath,
+      platform: "win32",
+      access: mockAccess(new Set()),
+    });
+    expect(result).toBe(customPath);
+  });
+
+  it("returns custom path as-is on windows when no variant found", () => {
+    const customPath = "C:\\nvm4w\\nodejs\\pi";
+    const result = resolvePiBinary({
+      customPath,
+      platform: "win32",
+      access: mockAccess(new Set()),
+    });
+    expect(result).toBe(customPath);
+  });
+
+  it("returns custom path as-is on windows when it has any extension", () => {
+    const customPath = "C:\\nvm4w\\nodejs\\pi.bat";
+    const result = resolvePiBinary({
+      customPath,
+      platform: "win32",
+      access: mockAccess(new Set()),
+    });
+    expect(result).toBe(customPath);
+  });
+
+  it("does not resolve custom path extensions on unix", () => {
+    const customPath = "/usr/local/bin/pi";
+    const result = resolvePiBinary({
+      customPath,
+      platform: "linux",
+      access: mockAccess(new Set()),
+    });
+    expect(result).toBe(customPath);
+  });
+
   it("finds pi in workspace node_modules/.bin on unix", () => {
     const wsDir = "/projects/myapp";
     const piPath = join(wsDir, "node_modules", ".bin", "pi");
@@ -51,11 +113,42 @@ describe("resolvePiBinary", () => {
     expect(result).toBe(bunPath);
   });
 
-  it("skips global unix paths on windows", () => {
-    const home = "C:\\Users\\dev";
+  it("finds pi.cmd in APPDATA\\npm on windows", () => {
+    const appData = "C:\\Users\\dev\\AppData\\Roaming";
+    const piCmd = join(appData, "npm", "pi.cmd");
     const result = resolvePiBinary({
       platform: "win32",
-      home,
+      home: "C:\\Users\\dev",
+      appData,
+      localAppData: "",
+      workspaceDirs: [],
+      access: mockAccess(new Set([piCmd])),
+      pathEnv: "",
+    });
+    expect(result).toBe(piCmd);
+  });
+
+  it("finds pi.cmd in LOCALAPPDATA\\pnpm on windows", () => {
+    const localAppData = "C:\\Users\\dev\\AppData\\Local";
+    const piCmd = join(localAppData, "pnpm", "pi.cmd");
+    const result = resolvePiBinary({
+      platform: "win32",
+      home: "C:\\Users\\dev",
+      appData: "",
+      localAppData,
+      workspaceDirs: [],
+      access: mockAccess(new Set([piCmd])),
+      pathEnv: "",
+    });
+    expect(result).toBe(piCmd);
+  });
+
+  it("falls back to 'pi' on windows when nothing found", () => {
+    const result = resolvePiBinary({
+      platform: "win32",
+      home: "C:\\Users\\dev",
+      appData: "",
+      localAppData: "",
       workspaceDirs: [],
       access: mockAccess(new Set()),
       pathEnv: "",
@@ -64,14 +157,15 @@ describe("resolvePiBinary", () => {
   });
 
   it("finds pi in PATH on unix", () => {
+    const piPath = join("/usr/local/bin", "pi");
     const result = resolvePiBinary({
       platform: "linux",
       home: "/home/user",
       workspaceDirs: [],
-      access: mockAccess(new Set(["/usr/local/bin/pi"])),
+      access: mockAccess(new Set([piPath])),
       pathEnv: "/usr/bin:/usr/local/bin",
     });
-    expect(result).toBe("/usr/local/bin/pi");
+    expect(result).toBe(piPath);
   });
 
   it("finds pi.cmd in PATH on windows", () => {