fix(server): use shell on Windows for all provider spawns

Windows npm shims (e.g. C:\nvm4w\nodejs\codex) fail with ENOENT when
spawned without shell. Use `shell: true` on win32 for all provider
launches instead of the overly complex shouldUseWindowsShell function.

packages/cli/src/commands/daemon/status.ts

@@ -175,6 +175,7 @@ function checkProviderBinary(binary: string): { path: string | null; version: st
       timeout: 5000,
       stdio: ["ignore", "pipe", "pipe"],
       env,
+      shell: process.platform === "win32",
     }).trim();
     return { path: binaryPath, version: output || null };
   } catch {

packages/server/src/server/agent/provider-launch-config.test.ts

@@ -168,6 +168,24 @@ describe("findExecutable", () => {
     expect(env.Path).toContain("C:\\Users\\boudr\\.local\\bin");
   });
 
+  test("on Windows, preserves the first where.exe match", () => {
+    findExecutableDependencies.platform = vi.fn(() => "win32");
+    process.env.Path = "C:\\Windows\\System32";
+    findExecutableDependencies.execFileSync.mockImplementation(
+      ((command: string) => {
+        if (command === "powershell") {
+          return "C:\\Windows\\System32\r\nC:\\nvm4w\\nodejs\r\n";
+        }
+        if (command === "where.exe") {
+          return "C:\\nvm4w\\nodejs\\codex\r\nC:\\nvm4w\\nodejs\\codex.cmd\r\n";
+        }
+        throw new Error(`unexpected command ${command}`);
+      }) as any,
+    );
+
+    expect(findExecutable("codex", findExecutableDependencies)).toBe("C:\\nvm4w\\nodejs\\codex");
+  });
+
   test("uses the last line from login-shell which output", () => {
     findExecutableDependencies.shell = "/bin/zsh";
     findExecutableDependencies.execSync.mockReturnValue(

packages/server/src/server/agent/provider-launch-config.ts

@@ -187,7 +187,10 @@ export function applyProviderEnv(
  * user opened a terminal and typed the command.  If that fails (e.g. the login
  * shell itself errors) we fall back to a plain `which`.
  *
- * On Windows the system PATH is always available, so `where.exe` is sufficient.
+ * On Windows we augment the daemon PATH with machine/user registry PATH values
+ * and return the first `where.exe` match. Launch-time execution decides whether
+ * the resolved path needs `cmd.exe` semantics (for example npm shims under
+ * nvm4w such as `C:\nvm4w\nodejs\codex`).
  */
 export function findExecutable(
   name: string,
@@ -228,8 +231,12 @@ export function findExecutable(
         Path: resolvedPath,
       };
       const out = deps.execFileSync("where.exe", [trimmed], { encoding: "utf8", env }).trim();
-      const firstLine = out.split(/\r?\n/)[0]?.trim();
-      return firstLine || null;
+      return (
+        out
+          .split(/\r?\n/)
+          .map((line) => line.trim())
+          .find((line) => line.length > 0) ?? null
+      );
     } catch {
       return null;
     }

packages/server/src/server/agent/providers/claude-agent.ts

@@ -219,6 +219,7 @@ function applyRuntimeSettingsToClaudeOptions(
           ...applyProviderEnv(spawnOptions.env, runtimeSettings),
           ...(launchEnv ?? {}),
         },
+        shell: process.platform === "win32",
         signal: spawnOptions.signal,
         stdio: ["pipe", "pipe", "pipe"],
       });

packages/server/src/server/agent/providers/codex-app-server-agent.ts

@@ -3421,6 +3421,7 @@ export class CodexAppServerAgentClient implements AgentClient {
     );
     return spawn(launchPrefix.command, [...launchPrefix.args, "app-server"], {
       detached: process.platform !== "win32",
+      shell: process.platform === "win32",
       stdio: ["pipe", "pipe", "pipe"],
       env: buildCodexAppServerEnv(this.runtimeSettings, launchEnv),
     });

packages/server/src/server/agent/providers/opencode-agent.ts

@@ -336,6 +336,7 @@ export class OpenCodeServerManager {
         launchPrefix.command,
         [...launchPrefix.args, "serve", "--port", String(this.port)],
         {
+          shell: process.platform === "win32",
           stdio: ["ignore", "pipe", "pipe"],
           env: applyProviderEnv(process.env, this.runtimeSettings),
         },