fix(platform): detect Windows fnm CLI shims under GUI-launched PATH (#3062)

Scan %LOCALAPPDATA%\fnm\node-versions, fnm_multishells session dirs,
and %APPDATA%\npm when building wellKnownUserToolchainBins on Windows
so packaged Open Design finds Codex and other npm globals installed via
fnm even when launched from Start Menu without an initialized shell PATH.

apps/daemon/tests/runtimes/env-and-detection.test.ts

@@ -363,6 +363,30 @@ test('resolveAgentExecutable accepts Windows CODEX_BIN overrides with executable
   }
 });
 
+test('resolveAgentExecutable searches Windows fnm multishell shims under a minimal GUI PATH (#3062)', () => {
+  const home = mkdtempSync(join(tmpdir(), 'od-agent-fnm-multishell-'));
+  const localAppData = join(home, 'AppData', 'Local');
+  const fnmMultishell = join(localAppData, 'fnm_multishells', '12345-abcd');
+  try {
+    return withEnvSnapshot(['PATH', 'PATHEXT', 'OD_AGENT_HOME', 'LOCALAPPDATA'], () => {
+      mkdirSync(fnmMultishell, { recursive: true });
+      writeFileSync(join(fnmMultishell, 'codex.CMD'), '@echo off\r\nexit /b 0\r\n');
+      process.env.OD_AGENT_HOME = home;
+      process.env.LOCALAPPDATA = localAppData;
+      process.env.PATH = '';
+      process.env.PATHEXT = '.EXE;.CMD;.BAT';
+
+      const resolved = withPlatform('win32', () =>
+        resolveAgentExecutable(minimalAgentDef({ id: 'codex', bin: 'codex' })),
+      );
+
+      assert.equal(resolved, join(fnmMultishell, 'codex.CMD'));
+    });
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
 test('detectAgents applies configured env while probing the CLI', async () => {
   const dir = mkdtempSync(join(tmpdir(), 'od-agent-env-'));
   try {

packages/platform/src/index.ts

@@ -625,6 +625,28 @@ export function wellKnownUserToolchainBins(
       dirs.push(dir);
     }
   }
+  if (process.platform === "win32") {
+    const localAppData =
+      resolveUserScopedHome(env.LOCALAPPDATA, home) ?? join(home, "AppData", "Local");
+    const appData =
+      resolveUserScopedHome(env.APPDATA, home) ?? join(home, "AppData", "Roaming");
+    dirs.push(join(appData, "npm"));
+    const fnmDir = typeof env.FNM_DIR === "string" ? env.FNM_DIR.trim() : "";
+    for (const root of [
+      join(localAppData, "fnm", "node-versions"),
+      ...(fnmDir.length > 0 ? [join(fnmDir, "node-versions")] : []),
+    ]) {
+      for (const dir of existingChildBinDirs(root, ["installation", "bin"])) {
+        dirs.push(dir);
+      }
+    }
+    // fnm exposes npm-global CLIs via per-shell shims under fnm_multishells
+    // after `fnm env`. GUI-launched Electron inherits a stripped PATH without
+    // those ephemeral dirs (issue #3062).
+    for (const dir of existingChildBinDirs(join(localAppData, "fnm_multishells"), [])) {
+      dirs.push(dir);
+    }
+  }
   return dirs;
 }
 

packages/platform/tests/index.test.ts

@@ -669,4 +669,35 @@ describe("wellKnownUserToolchainBins", () => {
       rmSync(home, { recursive: true, force: true });
     }
   });
+
+  it("includes Windows fnm node installs, multishell shims, and npm globals (#3062)", () => {
+    const originalPlatform = process.platform;
+    Object.defineProperty(process, "platform", { configurable: true, value: "win32" });
+    const home = mkdtempSync(join(tmpdir(), "wkutb-win-fnm-"));
+    const localAppData = join(home, "AppData", "Local");
+    const appData = join(home, "AppData", "Roaming");
+    const fnmNodeBin = join(localAppData, "fnm", "node-versions", "v20.20.2", "installation", "bin");
+    const fnmMultishell = join(localAppData, "fnm_multishells", "12345-abcd");
+    const npmGlobal = join(appData, "npm");
+    try {
+      mkdirSync(fnmNodeBin, { recursive: true });
+      mkdirSync(fnmMultishell, { recursive: true });
+      mkdirSync(npmGlobal, { recursive: true });
+      writeFileSync(join(fnmNodeBin, "marker"), "");
+      writeFileSync(join(fnmMultishell, "marker"), "");
+      writeFileSync(join(npmGlobal, "marker"), "");
+
+      const dirs = wellKnownUserToolchainBins({
+        home,
+        env: { LOCALAPPDATA: localAppData, APPDATA: appData },
+        includeSystemBins: false,
+      });
+      expect(dirs).toContain(fnmNodeBin);
+      expect(dirs).toContain(fnmMultishell);
+      expect(dirs).toContain(npmGlobal);
+    } finally {
+      Object.defineProperty(process, "platform", { configurable: true, value: originalPlatform });
+      rmSync(home, { recursive: true, force: true });
+    }
+  });
 });