diff --git a/packages/wxt/src/core/utils/__tests__/manifest.test.ts b/packages/wxt/src/core/utils/__tests__/manifest.test.ts
index 761a3d23..b521587a 100644
--- a/packages/wxt/src/core/utils/__tests__/manifest.test.ts
+++ b/packages/wxt/src/core/utils/__tests__/manifest.test.ts
@@ -10,6 +10,7 @@ import {
   fakeOptionsEntrypoint,
   fakePopupEntrypoint,
   fakeSidepanelEntrypoint,
+  fakeWxtDevServer,
   setFakeWxt,
 } from '../testing/fake-objects';
 import { Manifest } from 'webextension-polyfill';
@@ -1496,6 +1497,89 @@ describe('Manifest Utils', () => {
         expect(actual.host_permissions).toBeUndefined();
       });
     });
+
+    describe('Dev mode', () => {
+      it('should not add any code for production builds', async () => {
+        setFakeWxt({
+          config: {
+            command: 'build',
+          },
+          server: {
+            hostname: 'localhost',
+            port: 3000,
+            origin: 'http://localhost:3000',
+          },
+        });
+        const output = fakeBuildOutput();
+        const entrypoints: Entrypoint[] = [];
+
+        const { manifest: actual } = await generateManifest(
+          entrypoints,
+          output,
+        );
+
+        expect(actual.permissions).toBeUndefined();
+        expect(actual.content_security_policy).toBeUndefined();
+      });
+
+      it('should add required permissions for dev mode to function for MV2', async () => {
+        setFakeWxt({
+          config: {
+            command: 'serve',
+            manifestVersion: 2,
+          },
+          server: fakeWxtDevServer({
+            port: 3000,
+            hostname: 'localhost',
+            origin: 'http://localhost:3000',
+          }),
+        });
+        const output = fakeBuildOutput();
+        const entrypoints: Entrypoint[] = [];
+
+        const { manifest: actual } = await generateManifest(
+          entrypoints,
+          output,
+        );
+
+        expect(actual).toMatchObject({
+          content_security_policy:
+            "script-src 'self' http://localhost:3000; object-src 'self';",
+          permissions: ['http://localhost/*', 'tabs'],
+        });
+      });
+
+      it('should add required permissions for dev mode to function for MV3', async () => {
+        setFakeWxt({
+          config: {
+            command: 'serve',
+            manifestVersion: 3,
+            browser: 'chrome',
+          },
+          server: fakeWxtDevServer({
+            hostname: 'localhost',
+            port: 3000,
+            origin: 'http://localhost:3000',
+          }),
+        });
+        const output = fakeBuildOutput();
+        const entrypoints: Entrypoint[] = [];
+
+        const { manifest: actual } = await generateManifest(
+          entrypoints,
+          output,
+        );
+
+        expect(actual).toMatchObject({
+          content_security_policy: {
+            extension_pages:
+              "script-src 'self' 'wasm-unsafe-eval' http://localhost:3000; object-src 'self';",
+          },
+          host_permissions: ['http://localhost/*'],
+          permissions: ['tabs', 'scripting'],
+        });
+      });
+    });
   });
 
   describe('stripPathFromMatchPattern', () => {
diff --git a/packages/wxt/src/core/utils/testing/fake-objects.ts b/packages/wxt/src/core/utils/testing/fake-objects.ts
index a1c60b46..470325af 100644
--- a/packages/wxt/src/core/utils/testing/fake-objects.ts
+++ b/packages/wxt/src/core/utils/testing/fake-objects.ts
@@ -311,10 +311,27 @@ export const fakeWxt = fakeObjectCreator<Wxt>(() => ({
   logger: mock(),
   reloadConfig: vi.fn(),
   pm: mock(),
-  server: faker.helpers.arrayElement([undefined, mock<WxtDevServer>()]),
+  server: faker.helpers.arrayElement([undefined, fakeWxtDevServer()]),
   builder: mock(),
 }));
 
+export const fakeWxtDevServer = fakeObjectCreator<WxtDevServer>(() => ({
+  currentOutput: fakeBuildOutput(),
+  hostname: 'localhost',
+  origin: 'http://localhost:3000',
+  port: 3000,
+  reloadContentScript: vi.fn(),
+  reloadExtension: vi.fn(),
+  reloadPage: vi.fn(),
+  restart: vi.fn(),
+  restartBrowser: vi.fn(),
+  start: vi.fn(),
+  stop: vi.fn(),
+  transformHtml: vi.fn(),
+  watcher: mock(),
+  ws: mock(),
+}));
+
 export function setFakeWxt(overrides?: DeepPartial<Wxt>) {
   const wxt = fakeWxt(overrides);
   setWxtForTesting(wxt);