diff --git a/src/cli/http.test.ts b/src/cli/http.test.ts
index 7d013fc..617e6a0 100644
--- a/src/cli/http.test.ts
+++ b/src/cli/http.test.ts
@@ -101,7 +101,7 @@ describe('startServer', () => {
     const mkdirSpy = spyOn(fs, 'mkdirSync').mockImplementation(() => undefined);
     const openSpy = spyOn(fs, 'openSync').mockReturnValue(99);
     const closeSpy = spyOn(fs, 'closeSync').mockImplementation(() => {});
-    const fakeChild = { unref: mock(() => {}) };
+    const fakeChild = { unref: mock(() => {}), on: mock(() => {}) };
     const spawnMock = mock(() => fakeChild);
 
     globalThis.fetch = mock(
@@ -152,7 +152,7 @@ describe('startServer', () => {
 
   test('spawns server and resolves when it becomes reachable', async () => {
     const existsSpy = spyOn(fs, 'existsSync').mockReturnValue(true);
-    const fakeChild = { unref: mock(() => {}) };
+    const fakeChild = { unref: mock(() => {}), on: mock(() => {}) };
     const spawnMock = mock(() => fakeChild);
 
     let calls = 0;
@@ -162,6 +162,11 @@ describe('startServer', () => {
       return new Response('[]', { status: 200 });
     }) as unknown as typeof fetch;
 
+    const configModule = await import('../config');
+    const configSpy = spyOn(configModule, 'loadConfig').mockReturnValue({
+      ...configModule.DEFAULT_CONFIG,
+    });
+
     const { startServer } = await import('./http');
     await startServer(10000, spawnMock as never);
 
@@ -169,11 +174,12 @@ describe('startServer', () => {
     expect(fakeChild.unref).toHaveBeenCalled();
 
     existsSpy.mockRestore();
+    configSpy.mockRestore();
   });
 
   test('exits with error when server does not start within timeout', async () => {
     const existsSpy = spyOn(fs, 'existsSync').mockReturnValue(true);
-    const spawnMock = mock(() => ({ unref: () => {} }));
+    const spawnMock = mock(() => ({ unref: () => {}, on: () => {} }));
     const exitSpy = spyOn(process, 'exit').mockImplementation((() => {}) as () => never);
     const errorSpy = spyOn(console, 'error').mockImplementation(() => {});
 
@@ -181,6 +187,11 @@ describe('startServer', () => {
       throw new Error('not yet');
     }) as unknown as typeof fetch;
 
+    const configModule = await import('../config');
+    const configSpy = spyOn(configModule, 'loadConfig').mockReturnValue({
+      ...configModule.DEFAULT_CONFIG,
+    });
+
     const { startServer } = await import('./http');
     await startServer(100, spawnMock as never);
 
@@ -190,6 +201,7 @@ describe('startServer', () => {
     existsSpy.mockRestore();
     exitSpy.mockRestore();
     errorSpy.mockRestore();
+    configSpy.mockRestore();
   });
 });
 
diff --git a/src/cli/http.ts b/src/cli/http.ts
index 06ae6af..2f4d24b 100644
--- a/src/cli/http.ts
+++ b/src/cli/http.ts
@@ -39,11 +39,23 @@ export async function isServerRunning(): Promise<boolean> {
  */
 export async function startServer(timeoutMs = 10000, _spawn = childProcess.spawn): Promise<void> {
   const isBun = typeof (globalThis as Record<string, unknown>).Bun !== 'undefined';
-  const isTs = isBun && __filename.endsWith('.ts');
+
+  // On Windows, Bun's net.Socket doesn't support the fd-based named-pipe
+  // wrapping that node-pty's ConPTY backend requires, so node-pty fails under
+  // Bun on Windows. bunx works because its #!/usr/bin/env node shim runs the
+  // server with Node.js instead. Mirror that here explicitly.
+  const useNode = process.platform === 'win32' && isBun;
+  const serverExec = useNode ? 'node' : process.execPath;
+
+  // When the executor is Node.js it cannot run .ts files directly, so always
+  // resolve to the compiled .js entry regardless of whether the CLI itself is
+  // running from source.
+  const isTs = isBun && !useNode && __filename.endsWith('.ts');
   const serverEntry = path.resolve(__dirname, isTs ? '../server/index.ts' : '../server/index.js');
   if (!fs.existsSync(serverEntry)) {
     console.error(`webtty: server entry not found at ${serverEntry}`);
-    process.exit(1);
+    (process.exit as (code?: number) => void)(1);
+    return;
   }
 
   const config = loadConfig();
@@ -56,11 +68,18 @@ export async function startServer(timeoutMs = 10000, _spawn = childProcess.spawn
     stdio = ['ignore', logFd, logFd];
   }
 
-  const child = _spawn(process.execPath, [serverEntry], {
+  const child = _spawn(serverExec, [serverEntry], {
     detached: true,
     stdio,
     env: { ...process.env, PORT: String(PORT) },
   });
+  child.on('error', (err) => {
+    const hint = useNode
+      ? ' (Node.js must be on PATH when running webtty under Bun on Windows)'
+      : '';
+    console.error(`webtty: failed to start server: ${err.message}${hint}`);
+    process.exit(1);
+  });
   child.unref();
   if (logFd !== undefined) fs.closeSync(logFd);
 
diff --git a/src/server/websocket.test.ts b/src/server/websocket.test.ts
index e6c1202..0d641bc 100644
--- a/src/server/websocket.test.ts
+++ b/src/server/websocket.test.ts
@@ -221,9 +221,9 @@ describe('websocket', () => {
     }>;
     const session = sessions.find((s) => s.id === 'ws-test-pid-route');
     expect(session).toBeDefined();
-    expect(typeof session!.pid).toBe('number');
+    expect(typeof session?.pid).toBe('number');
 
-    const res = await fetch(`${baseUrl}/p/${session!.pid}`, { redirect: 'manual' });
+    const res = await fetch(`${baseUrl}/p/${session?.pid}`, { redirect: 'manual' });
     expect(res.status).toBe(302);
     expect(res.headers.get('location')).toBe('/s/ws-test-pid-route');
   });