diff --git a/apps/dev-playground/client/src/appkit-types/analytics.d.ts b/apps/dev-playground/client/src/appkit-types/analytics.d.ts
index 0e0ae0b0..43666dd0 100644
--- a/apps/dev-playground/client/src/appkit-types/analytics.d.ts
+++ b/apps/dev-playground/client/src/appkit-types/analytics.d.ts
@@ -119,10 +119,10 @@ declare module "@databricks/appkit-ui/react" {
         result: Array<{
           /** @sqlType STRING */
           string_value: string;
-          /** @sqlType STRING */
-          number_value: string;
-          /** @sqlType STRING */
-          boolean_value: string;
+          /** @sqlType INT */
+          number_value: number;
+          /** @sqlType BOOLEAN */
+          boolean_value: boolean;
           /** @sqlType STRING */
           date_value: string;
           /** @sqlType STRING */
diff --git a/apps/dev-playground/client/src/routeTree.gen.ts b/apps/dev-playground/client/src/routeTree.gen.ts
index 99ac75fc..4a9f72fa 100644
--- a/apps/dev-playground/client/src/routeTree.gen.ts
+++ b/apps/dev-playground/client/src/routeTree.gen.ts
@@ -9,6 +9,7 @@
 // Additionally, you should also exclude this file from your linter and/or formatter to prevent it from being checked or modified.
 
 import { Route as rootRouteImport } from './routes/__root'
+import { Route as VectorSearchRouteRouteImport } from './routes/vector-search.route'
 import { Route as TypeSafetyRouteRouteImport } from './routes/type-safety.route'
 import { Route as TelemetryRouteRouteImport } from './routes/telemetry.route'
 import { Route as SqlHelpersRouteRouteImport } from './routes/sql-helpers.route'
@@ -23,6 +24,11 @@ import { Route as ArrowAnalyticsRouteRouteImport } from './routes/arrow-analytic
 import { Route as AnalyticsRouteRouteImport } from './routes/analytics.route'
 import { Route as IndexRouteImport } from './routes/index'
 
+const VectorSearchRouteRoute = VectorSearchRouteRouteImport.update({
+  id: '/vector-search',
+  path: '/vector-search',
+  getParentRoute: () => rootRouteImport,
+} as any)
 const TypeSafetyRouteRoute = TypeSafetyRouteRouteImport.update({
   id: '/type-safety',
   path: '/type-safety',
@@ -103,6 +109,7 @@ export interface FileRoutesByFullPath {
   '/sql-helpers': typeof SqlHelpersRouteRoute
   '/telemetry': typeof TelemetryRouteRoute
   '/type-safety': typeof TypeSafetyRouteRoute
+  '/vector-search': typeof VectorSearchRouteRoute
 }
 export interface FileRoutesByTo {
   '/': typeof IndexRoute
@@ -118,6 +125,7 @@ export interface FileRoutesByTo {
   '/sql-helpers': typeof SqlHelpersRouteRoute
   '/telemetry': typeof TelemetryRouteRoute
   '/type-safety': typeof TypeSafetyRouteRoute
+  '/vector-search': typeof VectorSearchRouteRoute
 }
 export interface FileRoutesById {
   __root__: typeof rootRouteImport
@@ -134,6 +142,7 @@ export interface FileRoutesById {
   '/sql-helpers': typeof SqlHelpersRouteRoute
   '/telemetry': typeof TelemetryRouteRoute
   '/type-safety': typeof TypeSafetyRouteRoute
+  '/vector-search': typeof VectorSearchRouteRoute
 }
 export interface FileRouteTypes {
   fileRoutesByFullPath: FileRoutesByFullPath
@@ -151,6 +160,7 @@ export interface FileRouteTypes {
     | '/sql-helpers'
     | '/telemetry'
     | '/type-safety'
+    | '/vector-search'
   fileRoutesByTo: FileRoutesByTo
   to:
     | '/'
@@ -166,6 +176,7 @@ export interface FileRouteTypes {
     | '/sql-helpers'
     | '/telemetry'
     | '/type-safety'
+    | '/vector-search'
   id:
     | '__root__'
     | '/'
@@ -181,6 +192,7 @@ export interface FileRouteTypes {
     | '/sql-helpers'
     | '/telemetry'
     | '/type-safety'
+    | '/vector-search'
   fileRoutesById: FileRoutesById
 }
 export interface RootRouteChildren {
@@ -197,10 +209,18 @@ export interface RootRouteChildren {
   SqlHelpersRouteRoute: typeof SqlHelpersRouteRoute
   TelemetryRouteRoute: typeof TelemetryRouteRoute
   TypeSafetyRouteRoute: typeof TypeSafetyRouteRoute
+  VectorSearchRouteRoute: typeof VectorSearchRouteRoute
 }
 
 declare module '@tanstack/react-router' {
   interface FileRoutesByPath {
+    '/vector-search': {
+      id: '/vector-search'
+      path: '/vector-search'
+      fullPath: '/vector-search'
+      preLoaderRoute: typeof VectorSearchRouteRouteImport
+      parentRoute: typeof rootRouteImport
+    }
     '/type-safety': {
       id: '/type-safety'
       path: '/type-safety'
@@ -309,6 +329,7 @@ const rootRouteChildren: RootRouteChildren = {
   SqlHelpersRouteRoute: SqlHelpersRouteRoute,
   TelemetryRouteRoute: TelemetryRouteRoute,
   TypeSafetyRouteRoute: TypeSafetyRouteRoute,
+  VectorSearchRouteRoute: VectorSearchRouteRoute,
 }
 export const routeTree = rootRouteImport
   ._addFileChildren(rootRouteChildren)
diff --git a/apps/dev-playground/server/index.ts b/apps/dev-playground/server/index.ts
index 913f547c..87dbf7d2 100644
--- a/apps/dev-playground/server/index.ts
+++ b/apps/dev-playground/server/index.ts
@@ -26,7 +26,7 @@ function createMockClient() {
 
 createApp({
   plugins: [
-    server({ autoStart: false }),
+    server(),
     reconnect(),
     telemetryExamples(),
     analytics({}),
@@ -49,9 +49,8 @@ createApp({
     // }),
   ],
   ...(process.env.APPKIT_E2E_TEST && { client: createMockClient() }),
-}).then((appkit) => {
-  appkit.server
-    .extend((app) => {
+  onPluginsReady(appkit) {
+    appkit.server.extend((app) => {
       app.get("/sp", (_req, res) => {
         appkit.analytics
           .query("SELECT * FROM samples.nyctaxi.trips;")
@@ -86,6 +85,6 @@ createApp({
             });
           });
       });
-    })
-    .start();
-});
+    });
+  },
+}).catch(console.error);
diff --git a/docs/docs/api/appkit/Class.ServerError.md b/docs/docs/api/appkit/Class.ServerError.md
index d3dce68e..cce86cad 100644
--- a/docs/docs/api/appkit/Class.ServerError.md
+++ b/docs/docs/api/appkit/Class.ServerError.md
@@ -6,7 +6,6 @@ Use for server start/stop issues, configuration conflicts, etc.
 ## Example
 
 ```typescript
-throw new ServerError("Cannot get server when autoStart is true");
 throw new ServerError("Server not started");
 ```
 
@@ -151,26 +150,6 @@ Create a human-readable string representation
 
 ***
 
-### autoStartConflict()
-
-```ts
-static autoStartConflict(operation: string): ServerError;
-```
-
-Create a server error for autoStart conflict
-
-#### Parameters
-
-| Parameter | Type |
-| ------ | ------ |
-| `operation` | `string` |
-
-#### Returns
-
-`ServerError`
-
-***
-
 ### clientDirectoryNotFound()
 
 ```ts
diff --git a/docs/docs/api/appkit/Function.createApp.md b/docs/docs/api/appkit/Function.createApp.md
index cb703386..6a0b7cb2 100644
--- a/docs/docs/api/appkit/Function.createApp.md
+++ b/docs/docs/api/appkit/Function.createApp.md
@@ -4,6 +4,7 @@
 function createApp<T>(config: {
   cache?: CacheConfig;
   client?: WorkspaceClient;
+  onPluginsReady?: (appkit: PluginMap<T>) => void | Promise<void>;
   plugins?: T;
   telemetry?: TelemetryConfig;
 }): Promise<PluginMap<T>>;
@@ -13,6 +14,9 @@ Bootstraps AppKit with the provided configuration.
 
 Initializes telemetry, cache, and service context, then registers plugins
 in phase order (core, normal, deferred) and awaits their setup.
+If a `onPluginsReady` callback is provided it runs after plugin setup but
+before the server starts, giving you access to the full appkit handle
+for registering custom routes or performing async setup.
 The returned object maps each plugin name to its `exports()` API,
 with an `asUser(req)` method for user-scoped execution.
 
@@ -26,9 +30,10 @@ with an `asUser(req)` method for user-scoped execution.
 
 | Parameter | Type |
 | ------ | ------ |
-| `config` | \{ `cache?`: [`CacheConfig`](Interface.CacheConfig.md); `client?`: `WorkspaceClient`; `plugins?`: `T`; `telemetry?`: [`TelemetryConfig`](Interface.TelemetryConfig.md); \} |
+| `config` | \{ `cache?`: [`CacheConfig`](Interface.CacheConfig.md); `client?`: `WorkspaceClient`; `onPluginsReady?`: (`appkit`: `PluginMap`\<`T`\>) => `void` \| `Promise`\<`void`\>; `plugins?`: `T`; `telemetry?`: [`TelemetryConfig`](Interface.TelemetryConfig.md); \} |
 | `config.cache?` | [`CacheConfig`](Interface.CacheConfig.md) |
 | `config.client?` | `WorkspaceClient` |
+| `config.onPluginsReady?` | (`appkit`: `PluginMap`\<`T`\>) => `void` \| `Promise`\<`void`\> |
 | `config.plugins?` | `T` |
 | `config.telemetry?` | [`TelemetryConfig`](Interface.TelemetryConfig.md) |
 
@@ -51,12 +56,12 @@ await createApp({
 ```ts
 import { createApp, server, analytics } from "@databricks/appkit";
 
-const appkit = await createApp({
-  plugins: [server({ autoStart: false }), analytics({})],
-});
-
-appkit.server.extend((app) => {
-  app.get("/custom", (_req, res) => res.json({ ok: true }));
+await createApp({
+  plugins: [server(), analytics({})],
+  onPluginsReady(appkit) {
+    appkit.server.extend((app) => {
+      app.get("/custom", (_req, res) => res.json({ ok: true }));
+    });
+  },
 });
-await appkit.server.start();
 ```
diff --git a/docs/docs/plugins/server.md b/docs/docs/plugins/server.md
index 389828dc..6cfaa7b7 100644
--- a/docs/docs/plugins/server.md
+++ b/docs/docs/plugins/server.md
@@ -36,22 +36,38 @@ await createApp({
 });
 ```
 
-## Manual server start example
+## Custom routes example
 
-When you need to extend Express with custom routes:
+Use the `onPluginsReady` callback to extend Express with custom routes before the server starts:
 
 ```ts
 import { createApp, server } from "@databricks/appkit";
 
-const appkit = await createApp({
-  plugins: [server({ autoStart: false })],
+await createApp({
+  plugins: [server()],
+  onPluginsReady(appkit) {
+    appkit.server.extend((app) => {
+      app.get("/custom", (_req, res) => res.json({ ok: true }));
+    });
+  },
 });
+```
 
-appkit.server.extend((app) => {
-  app.get("/custom", (_req, res) => res.json({ ok: true }));
-});
+The `onPluginsReady` callback also supports async operations:
 
-await appkit.server.start();
+```ts
+await createApp({
+  plugins: [server()],
+  async onPluginsReady(appkit) {
+    const pool = await initializeDatabase();
+    appkit.server.extend((app) => {
+      app.get("/data", async (_req, res) => {
+        const result = await pool.query("SELECT 1");
+        res.json(result);
+      });
+    });
+  },
+});
 ```
 
 ## Configuration options
@@ -64,7 +80,6 @@ await createApp({
     server({
       port: 8000,          // default: Number(process.env.DATABRICKS_APP_PORT) || 8000
       host: "0.0.0.0",     // default: process.env.FLASK_RUN_HOST || "0.0.0.0"
-      autoStart: true,     // default: true
       staticPath: "dist",  // optional: force a specific static directory
     }),
   ],
diff --git a/packages/appkit/src/core/appkit.ts b/packages/appkit/src/core/appkit.ts
index a2cba994..40fd1fcd 100644
--- a/packages/appkit/src/core/appkit.ts
+++ b/packages/appkit/src/core/appkit.ts
@@ -167,6 +167,7 @@ export class AppKit<TPlugins extends InputPluginMap> {
       telemetry?: TelemetryConfig;
       cache?: CacheConfig;
       client?: WorkspaceClient;
+      onPluginsReady?: (appkit: PluginMap<T>) => void | Promise<void>;
     } = {},
   ): Promise<PluginMap<T>> {
     // Initialize core services
@@ -200,7 +201,16 @@ export class AppKit<TPlugins extends InputPluginMap> {
 
     await Promise.all(instance.#setupPromises);
 
-    return instance as unknown as PluginMap<T>;
+    const handle = instance as unknown as PluginMap<T>;
+
+    await config.onPluginsReady?.(handle);
+
+    const serverPlugin = instance.#pluginInstances.server;
+    if (serverPlugin && typeof (serverPlugin as any).start === "function") {
+      await (serverPlugin as any).start();
+    }
+
+    return handle;
   }
 
   private static preparePlugins(
@@ -222,6 +232,9 @@ export class AppKit<TPlugins extends InputPluginMap> {
  *
  * Initializes telemetry, cache, and service context, then registers plugins
  * in phase order (core, normal, deferred) and awaits their setup.
+ * If a `onPluginsReady` callback is provided it runs after plugin setup but
+ * before the server starts, giving you access to the full appkit handle
+ * for registering custom routes or performing async setup.
  * The returned object maps each plugin name to its `exports()` API,
  * with an `asUser(req)` method for user-scoped execution.
  *
@@ -236,18 +249,18 @@ export class AppKit<TPlugins extends InputPluginMap> {
  * });
  * ```
  *
- * @example Extended Server with analytics and custom endpoint
+ * @example Server with custom routes via onPluginsReady
  * ```ts
  * import { createApp, server, analytics } from "@databricks/appkit";
  *
- * const appkit = await createApp({
- *   plugins: [server({ autoStart: false }), analytics({})],
- * });
- *
- * appkit.server.extend((app) => {
- *   app.get("/custom", (_req, res) => res.json({ ok: true }));
+ * await createApp({
+ *   plugins: [server(), analytics({})],
+ *   onPluginsReady(appkit) {
+ *     appkit.server.extend((app) => {
+ *       app.get("/custom", (_req, res) => res.json({ ok: true }));
+ *     });
+ *   },
  * });
- * await appkit.server.start();
  * ```
  */
 export async function createApp<
@@ -258,6 +271,7 @@ export async function createApp<
     telemetry?: TelemetryConfig;
     cache?: CacheConfig;
     client?: WorkspaceClient;
+    onPluginsReady?: (appkit: PluginMap<T>) => void | Promise<void>;
   } = {},
 ): Promise<PluginMap<T>> {
   return AppKit._createApp(config);
diff --git a/packages/appkit/src/errors/server.ts b/packages/appkit/src/errors/server.ts
index 6af5b59f..d45148d8 100644
--- a/packages/appkit/src/errors/server.ts
+++ b/packages/appkit/src/errors/server.ts
@@ -6,7 +6,6 @@ import { AppKitError } from "./base";
  *
  * @example
  * ```typescript
- * throw new ServerError("Cannot get server when autoStart is true");
  * throw new ServerError("Server not started");
  * ```
  */
@@ -15,15 +14,6 @@ export class ServerError extends AppKitError {
   readonly statusCode = 500;
   readonly isRetryable = false;
 
-  /**
-   * Create a server error for autoStart conflict
-   */
-  static autoStartConflict(operation: string): ServerError {
-    return new ServerError(`Cannot ${operation} when autoStart is true`, {
-      context: { operation },
-    });
-  }
-
   /**
    * Create a server error for server not started
    */
diff --git a/packages/appkit/src/errors/tests/errors.test.ts b/packages/appkit/src/errors/tests/errors.test.ts
index c404a18f..347ce1c0 100644
--- a/packages/appkit/src/errors/tests/errors.test.ts
+++ b/packages/appkit/src/errors/tests/errors.test.ts
@@ -348,12 +348,6 @@ describe("ServerError", () => {
     expect(error.isRetryable).toBe(false);
   });
 
-  test("autoStartConflict should create proper error", () => {
-    const error = ServerError.autoStartConflict("get server");
-    expect(error.message).toBe("Cannot get server when autoStart is true");
-    expect(error.context?.operation).toBe("get server");
-  });
-
   test("notStarted should create proper error", () => {
     const error = ServerError.notStarted();
     expect(error.message).toContain("Server not started");
diff --git a/packages/appkit/src/plugins/analytics/tests/analytics.integration.test.ts b/packages/appkit/src/plugins/analytics/tests/analytics.integration.test.ts
index cb73394a..0cec2298 100644
--- a/packages/appkit/src/plugins/analytics/tests/analytics.integration.test.ts
+++ b/packages/appkit/src/plugins/analytics/tests/analytics.integration.test.ts
@@ -46,13 +46,11 @@ describe("Analytics Plugin Integration", () => {
         serverPlugin({
           port: TEST_PORT,
           host: "127.0.0.1",
-          autoStart: false,
         }),
         analytics({}),
       ],
     });
 
-    await app.server.start();
     server = app.server.getServer();
     baseUrl = `http://127.0.0.1:${TEST_PORT}`;
   });
diff --git a/packages/appkit/src/plugins/files/tests/plugin.integration.test.ts b/packages/appkit/src/plugins/files/tests/plugin.integration.test.ts
index 55989148..add134d7 100644
--- a/packages/appkit/src/plugins/files/tests/plugin.integration.test.ts
+++ b/packages/appkit/src/plugins/files/tests/plugin.integration.test.ts
@@ -87,13 +87,11 @@ describe("Files Plugin Integration", () => {
         serverPlugin({
           port: TEST_PORT,
           host: "127.0.0.1",
-          autoStart: false,
         }),
         files(),
       ],
     });
 
-    await appkit.server.start();
     server = appkit.server.getServer();
     baseUrl = `http://127.0.0.1:${TEST_PORT}`;
   });
diff --git a/packages/appkit/src/plugins/server/index.ts b/packages/appkit/src/plugins/server/index.ts
index e7b9b31a..6c484114 100644
--- a/packages/appkit/src/plugins/server/index.ts
+++ b/packages/appkit/src/plugins/server/index.ts
@@ -27,17 +27,23 @@ const logger = createLogger("server");
  * This plugin is responsible for starting the server and serving the static files.
  * It also handles the remote tunneling for development purposes.
  *
+ * The server is started automatically by `createApp` after all plugins are set up
+ * and the optional `onPluginsReady` callback has run.
+ *
  * @example
  * ```ts
  * createApp({
- *   plugins: [server(), telemetryExamples(), analytics({})],
+ *   plugins: [server(), analytics({})],
+ *   onPluginsReady(appkit) {
+ *     appkit.server.extend((app) => {
+ *       app.get("/custom", (_req, res) => res.json({ ok: true }));
+ *     });
+ *   },
  * });
  * ```
- *
  */
 export class ServerPlugin extends Plugin {
   public static DEFAULT_CONFIG = {
-    autoStart: true,
     host: process.env.FLASK_RUN_HOST || "0.0.0.0",
     port: Number(process.env.DATABRICKS_APP_PORT) || 8000,
   };
@@ -54,6 +60,13 @@ export class ServerPlugin extends Plugin {
   static phase: PluginPhase = "deferred";
 
   constructor(config: ServerConfig) {
+    if ("autoStart" in config) {
+      throw new ServerError(
+        "server({ autoStart }) has been removed. " +
+          "The server is now started automatically by createApp.\n\n" +
+          "Run `npx appkit codemod customize-callback --write` to auto-migrate.",
+      );
+    }
     super(config);
     this.config = config;
     this.serverApplication = express();
@@ -65,12 +78,7 @@ export class ServerPlugin extends Plugin {
     ]);
   }
 
-  /** Setup the server plugin. */
-  async setup() {
-    if (this.shouldAutoStart()) {
-      await this.start();
-    }
-  }
+  async setup() {}
 
   /** Get the server configuration. */
   getConfig() {
@@ -79,11 +87,6 @@ export class ServerPlugin extends Plugin {
     return config;
   }
 
-  /** Check if the server should auto start. */
-  shouldAutoStart() {
-    return this.config.autoStart;
-  }
-
   /**
    * Start the server.
    *
@@ -148,14 +151,10 @@ export class ServerPlugin extends Plugin {
    *
    * Only use this method if you need to access the server instance for advanced usage like a custom websocket server, etc.
    *
-   * @throws {Error} If the server is not started or autoStart is true.
+   * @throws {Error} If the server has not started yet.
    * @returns {HTTPServer} The server instance.
    */
   getServer(): HTTPServer {
-    if (this.shouldAutoStart()) {
-      throw ServerError.autoStartConflict("get server");
-    }
-
     if (!this.server) {
       throw ServerError.notStarted();
     }
@@ -166,15 +165,13 @@ export class ServerPlugin extends Plugin {
   /**
    * Extend the server with custom routes or middleware.
    *
+   * Call this inside the `onPluginsReady` callback of `createApp` to register
+   * custom Express routes or middleware before the server starts listening.
+   *
    * @param fn - A function that receives the express application.
    * @returns The server plugin instance for chaining.
-   * @throws {Error} If autoStart is true.
    */
   extend(fn: (app: express.Application) => void) {
-    if (this.shouldAutoStart()) {
-      throw ServerError.autoStartConflict("extend server");
-    }
-
     this.serverExtensions.push(fn);
     return this;
   }
@@ -389,8 +386,6 @@ export class ServerPlugin extends Plugin {
   exports() {
     const self = this;
     return {
-      /** Start the server */
-      start: this.start,
       /** Extend the server with custom routes or middleware */
       extend(fn: (app: express.Application) => void) {
         self.extend(fn);
@@ -400,6 +395,19 @@ export class ServerPlugin extends Plugin {
       getServer: this.getServer,
       /** Get the server configuration */
       getConfig: this.getConfig,
+      /** @deprecated Server is now started automatically by createApp. */
+      start() {
+        throw new ServerError(
+          "server.start() has been removed. Use the onPluginsReady callback instead:\n\n" +
+            "  createApp({\n" +
+            "    plugins: [server(), ...],\n" +
+            "    onPluginsReady(appkit) {\n" +
+            "      appkit.server.extend(...);\n" +
+            "    },\n" +
+            "  });\n\n" +
+            "Run `npx appkit codemod customize-callback --write` to auto-migrate.",
+        );
+      },
     };
   }
 }
diff --git a/packages/appkit/src/plugins/server/manifest.json b/packages/appkit/src/plugins/server/manifest.json
index 11822beb..1112fbf5 100644
--- a/packages/appkit/src/plugins/server/manifest.json
+++ b/packages/appkit/src/plugins/server/manifest.json
@@ -11,11 +11,6 @@
     "schema": {
       "type": "object",
       "properties": {
-        "autoStart": {
-          "type": "boolean",
-          "default": true,
-          "description": "Automatically start the server on plugin setup"
-        },
         "host": {
           "type": "string",
           "default": "0.0.0.0",
diff --git a/packages/appkit/src/plugins/server/tests/server.integration.test.ts b/packages/appkit/src/plugins/server/tests/server.integration.test.ts
index c3a646ea..0b67e4c0 100644
--- a/packages/appkit/src/plugins/server/tests/server.integration.test.ts
+++ b/packages/appkit/src/plugins/server/tests/server.integration.test.ts
@@ -29,13 +29,10 @@ describe("ServerPlugin Integration", () => {
         serverPlugin({
           port: TEST_PORT,
           host: "127.0.0.1",
-          autoStart: false,
         }),
       ],
     });
 
-    // Start server manually
-    await app.server.start();
     server = app.server.getServer();
     baseUrl = `http://127.0.0.1:${TEST_PORT}`;
 
@@ -124,13 +121,11 @@ describe("ServerPlugin with custom plugin", () => {
         serverPlugin({
           port: TEST_PORT,
           host: "127.0.0.1",
-          autoStart: false,
         }),
         testPlugin({}),
       ],
     });
 
-    await app.server.start();
     server = app.server.getServer();
     baseUrl = `http://127.0.0.1:${TEST_PORT}`;
 
@@ -172,7 +167,7 @@ describe("ServerPlugin with custom plugin", () => {
   });
 });
 
-describe("ServerPlugin with extend()", () => {
+describe("ServerPlugin with extend() via onPluginsReady", () => {
   let server: Server;
   let baseUrl: string;
   let serviceContextMock: Awaited<ReturnType<typeof mockServiceContext>>;
@@ -188,19 +183,73 @@ describe("ServerPlugin with extend()", () => {
         serverPlugin({
           port: TEST_PORT,
           host: "127.0.0.1",
-          autoStart: false,
         }),
       ],
+      onPluginsReady(appkit) {
+        appkit.server.extend((expressApp) => {
+          expressApp.get("/custom", (_req, res) => {
+            res.json({ custom: true });
+          });
+        });
+      },
     });
 
-    // Add custom route via extend()
-    app.server.extend((expressApp) => {
-      expressApp.get("/custom", (_req, res) => {
-        res.json({ custom: true });
+    server = app.server.getServer();
+    baseUrl = `http://127.0.0.1:${TEST_PORT}`;
+
+    await new Promise((resolve) => setTimeout(resolve, 100));
+  });
+
+  afterAll(async () => {
+    serviceContextMock?.restore();
+    if (server) {
+      await new Promise<void>((resolve, reject) => {
+        server.close((err) => {
+          if (err) reject(err);
+          else resolve();
+        });
       });
+    }
+  });
+
+  test("custom route via extend() in onPluginsReady callback works", async () => {
+    const response = await fetch(`${baseUrl}/custom`);
+
+    expect(response.status).toBe(200);
+
+    const data = await response.json();
+    expect(data).toEqual({ custom: true });
+  });
+});
+
+describe("createApp with async onPluginsReady callback", () => {
+  let server: Server;
+  let baseUrl: string;
+  let serviceContextMock: Awaited<ReturnType<typeof mockServiceContext>>;
+  const TEST_PORT = 9885;
+
+  beforeAll(async () => {
+    setupDatabricksEnv();
+    ServiceContext.reset();
+    serviceContextMock = await mockServiceContext();
+
+    const app = await createApp({
+      plugins: [
+        serverPlugin({
+          port: TEST_PORT,
+          host: "127.0.0.1",
+        }),
+      ],
+      async onPluginsReady(appkit) {
+        await new Promise((resolve) => setTimeout(resolve, 10));
+        appkit.server.extend((expressApp) => {
+          expressApp.get("/async-custom", (_req, res) => {
+            res.json({ asyncSetup: true });
+          });
+        });
+      },
     });
 
-    await app.server.start();
     server = app.server.getServer();
     baseUrl = `http://127.0.0.1:${TEST_PORT}`;
 
@@ -219,12 +268,38 @@ describe("ServerPlugin with extend()", () => {
     }
   });
 
-  test("custom route via extend() works", async () => {
-    const response = await fetch(`${baseUrl}/custom`);
+  test("async onPluginsReady callback runs before server starts", async () => {
+    const response = await fetch(`${baseUrl}/async-custom`);
 
     expect(response.status).toBe(200);
 
     const data = await response.json();
-    expect(data).toEqual({ custom: true });
+    expect(data).toEqual({ asyncSetup: true });
+  });
+});
+
+describe("createApp without server plugin", () => {
+  let serviceContextMock: Awaited<ReturnType<typeof mockServiceContext>>;
+  let onPluginsReadyWasCalled = false;
+
+  beforeAll(async () => {
+    setupDatabricksEnv();
+    ServiceContext.reset();
+    serviceContextMock = await mockServiceContext();
+
+    await createApp({
+      plugins: [],
+      onPluginsReady() {
+        onPluginsReadyWasCalled = true;
+      },
+    });
+  });
+
+  afterAll(async () => {
+    serviceContextMock?.restore();
+  });
+
+  test("onPluginsReady callback is still called without server plugin", () => {
+    expect(onPluginsReadyWasCalled).toBe(true);
   });
 });
diff --git a/packages/appkit/src/plugins/server/tests/server.test.ts b/packages/appkit/src/plugins/server/tests/server.test.ts
index 22f18129..fae11fb5 100644
--- a/packages/appkit/src/plugins/server/tests/server.test.ts
+++ b/packages/appkit/src/plugins/server/tests/server.test.ts
@@ -197,19 +197,22 @@ describe("ServerPlugin", () => {
       const plugin = new ServerPlugin({
         port: 3000,
         host: "127.0.0.1",
-        autoStart: false,
       });
 
       const config = plugin.getConfig();
       expect(config.port).toBe(3000);
       expect(config.host).toBe("127.0.0.1");
-      expect(config.autoStart).toBe(false);
+    });
+
+    test("should throw when autoStart is passed", () => {
+      expect(() => new ServerPlugin({ autoStart: false } as any)).toThrow(
+        "server({ autoStart }) has been removed",
+      );
     });
   });
 
   describe("DEFAULT_CONFIG", () => {
     test("should have correct default values", () => {
-      expect(ServerPlugin.DEFAULT_CONFIG.autoStart).toBe(true);
       expect(ServerPlugin.DEFAULT_CONFIG.host).toBe("0.0.0.0");
       expect(ServerPlugin.DEFAULT_CONFIG.port).toBe(8000);
     });
@@ -220,30 +223,9 @@ describe("ServerPlugin", () => {
     });
   });
 
-  describe("shouldAutoStart", () => {
-    test("should return true when autoStart is true", () => {
-      const plugin = new ServerPlugin({ autoStart: true });
-      expect(plugin.shouldAutoStart()).toBe(true);
-    });
-
-    test("should return false when autoStart is false", () => {
-      const plugin = new ServerPlugin({ autoStart: false });
-      expect(plugin.shouldAutoStart()).toBe(false);
-    });
-  });
-
   describe("setup", () => {
-    test("should call start when autoStart is true", async () => {
-      const plugin = new ServerPlugin({ autoStart: true });
-      const startSpy = vi.spyOn(plugin, "start").mockResolvedValue({} as any);
-
-      await plugin.setup();
-
-      expect(startSpy).toHaveBeenCalled();
-    });
-
-    test("should not call start when autoStart is false", async () => {
-      const plugin = new ServerPlugin({ autoStart: false });
+    test("should be a no-op (server start is orchestrated by createApp)", async () => {
+      const plugin = new ServerPlugin({});
       const startSpy = vi.spyOn(plugin, "start").mockResolvedValue({} as any);
 
       await plugin.setup();
@@ -254,7 +236,7 @@ describe("ServerPlugin", () => {
 
   describe("start", () => {
     test("should call listen on express app", async () => {
-      const plugin = new ServerPlugin({ autoStart: false, port: 3000 });
+      const plugin = new ServerPlugin({ port: 3000 });
 
       await plugin.start();
 
@@ -267,7 +249,7 @@ describe("ServerPlugin", () => {
 
     test("should setup ViteDevServer in development mode", async () => {
       process.env.NODE_ENV = "development";
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
 
       await plugin.start();
 
@@ -277,7 +259,7 @@ describe("ServerPlugin", () => {
     });
 
     test("should register RemoteTunnelController middleware and set server", async () => {
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
 
       await plugin.start();
 
@@ -304,7 +286,7 @@ describe("ServerPlugin", () => {
         },
       };
 
-      const plugin = new ServerPlugin({ autoStart: false, plugins });
+      const plugin = new ServerPlugin({ plugins });
       await plugin.start();
 
       // Get the type function passed to express.json
@@ -348,7 +330,7 @@ describe("ServerPlugin", () => {
         },
       };
 
-      const plugin = new ServerPlugin({ autoStart: false, plugins });
+      const plugin = new ServerPlugin({ plugins });
       await plugin.start();
 
       const routerFn = (express as any).Router as ReturnType<typeof vi.fn>;
@@ -386,7 +368,7 @@ describe("ServerPlugin", () => {
         },
       };
 
-      const plugin = new ServerPlugin({ autoStart: false, plugins });
+      const plugin = new ServerPlugin({ plugins });
       await plugin.start();
 
       expect(plugins["plugin-a"].clientConfig).toHaveBeenCalled();
@@ -413,7 +395,7 @@ describe("ServerPlugin", () => {
         },
       };
 
-      const plugin = new ServerPlugin({ autoStart: false, plugins });
+      const plugin = new ServerPlugin({ plugins });
       await plugin.start();
 
       expect(plugins["plugin-null"].clientConfig).toHaveBeenCalled();
@@ -444,7 +426,7 @@ describe("ServerPlugin", () => {
         },
       };
 
-      const plugin = new ServerPlugin({ autoStart: false, plugins });
+      const plugin = new ServerPlugin({ plugins });
       await expect(plugin.start()).resolves.toBeDefined();
       expect(mockLoggerError).toHaveBeenCalledWith(
         "Plugin '%s' clientConfig() failed, skipping its config: %O",
@@ -457,7 +439,7 @@ describe("ServerPlugin", () => {
       process.env.NODE_ENV = "production";
       vi.mocked(fs.existsSync).mockReturnValue(true);
 
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
 
       await plugin.start();
 
@@ -470,7 +452,7 @@ describe("ServerPlugin", () => {
       process.env.NODE_ENV = "production";
       vi.mocked(fs.existsSync).mockReturnValue(false);
 
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
 
       await plugin.start();
 
@@ -479,8 +461,8 @@ describe("ServerPlugin", () => {
   });
 
   describe("extend", () => {
-    test("should add extension function when autoStart is false", () => {
-      const plugin = new ServerPlugin({ autoStart: false });
+    test("should add extension function and return plugin for chaining", () => {
+      const plugin = new ServerPlugin({});
       const extensionFn = vi.fn();
 
       const result = plugin.extend(extensionFn);
@@ -488,17 +470,8 @@ describe("ServerPlugin", () => {
       expect(result).toBe(plugin);
     });
 
-    test("should throw when autoStart is true", () => {
-      const plugin = new ServerPlugin({ autoStart: true });
-      const extensionFn = vi.fn();
-
-      expect(() => plugin.extend(extensionFn)).toThrow(
-        "Cannot extend server when autoStart is true",
-      );
-    });
-
     test("should call extension functions during start", async () => {
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
       const extensionFn = vi.fn();
 
       plugin.extend(extensionFn);
@@ -508,17 +481,18 @@ describe("ServerPlugin", () => {
     });
   });
 
-  describe("getServer", () => {
-    test("should throw when autoStart is true", () => {
-      const plugin = new ServerPlugin({ autoStart: true });
+  describe("exports().start() trap", () => {
+    test("should throw migration error when start() is called via exports", () => {
+      const plugin = new ServerPlugin({});
+      const exported = plugin.exports();
 
-      expect(() => plugin.getServer()).toThrow(
-        "Cannot get server when autoStart is true",
-      );
+      expect(() => exported.start()).toThrow("server.start() has been removed");
     });
+  });
 
+  describe("getServer", () => {
     test("should throw when server not started", () => {
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
 
       expect(() => plugin.getServer()).toThrow(
         "Server not started. Please start the server first by calling the start() method",
@@ -526,7 +500,7 @@ describe("ServerPlugin", () => {
     });
 
     test("should return server after start", async () => {
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
 
       await plugin.start();
       const server = plugin.getServer();
@@ -553,7 +527,7 @@ describe("ServerPlugin", () => {
   describe("logStartupInfo", () => {
     test("logs remote tunnel controller disabled when missing", () => {
       mockLoggerDebug.mockClear();
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
       (plugin as any).remoteTunnelController = undefined;
 
       (plugin as any).logStartupInfo();
@@ -565,7 +539,7 @@ describe("ServerPlugin", () => {
 
     test("logs remote tunnel allowed/active when controller present", () => {
       mockLoggerDebug.mockClear();
-      const plugin = new ServerPlugin({ autoStart: false });
+      const plugin = new ServerPlugin({});
       (plugin as any).remoteTunnelController = {
         isAllowedByEnv: () => true,
         isActive: () => true,
@@ -607,7 +581,6 @@ describe("ServerPlugin", () => {
         .mockImplementation(((_code?: number) => undefined) as any);
 
       const plugin = new ServerPlugin({
-        autoStart: false,
         plugins: {
           ok: {
             name: "ok",
diff --git a/packages/appkit/src/plugins/server/types.ts b/packages/appkit/src/plugins/server/types.ts
index e187cacc..f9f6ebce 100644
--- a/packages/appkit/src/plugins/server/types.ts
+++ b/packages/appkit/src/plugins/server/types.ts
@@ -5,6 +5,5 @@ export interface ServerConfig extends BasePluginConfig {
   port?: number;
   plugins?: Record<string, Plugin>;
   staticPath?: string;
-  autoStart?: boolean;
   host?: string;
 }
diff --git a/packages/shared/src/cli/commands/codemod/customize-callback.ts b/packages/shared/src/cli/commands/codemod/customize-callback.ts
new file mode 100644
index 00000000..9d4ac40f
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/customize-callback.ts
@@ -0,0 +1,478 @@
+import fs from "node:fs";
+import path from "node:path";
+import { Lang, parse } from "@ast-grep/napi";
+import { Command } from "commander";
+
+const SEARCH_DIRS = ["server", "src", "."];
+const CANDIDATE_NAMES = ["server.ts", "index.ts"];
+const SKIP_DIRS = new Set(["node_modules", "dist", "build", ".git"]);
+
+function findServerEntryFiles(rootDir: string): string[] {
+  const results: string[] = [];
+
+  for (const dir of SEARCH_DIRS) {
+    const absDir = path.resolve(rootDir, dir);
+    if (!fs.existsSync(absDir)) continue;
+
+    const files =
+      dir === "."
+        ? CANDIDATE_NAMES.map((n) => path.join(absDir, n)).filter(fs.existsSync)
+        : findTsFiles(absDir);
+
+    for (const file of files) {
+      const content = fs.readFileSync(file, "utf-8");
+      if (
+        content.includes("createApp") &&
+        content.includes("@databricks/appkit")
+      ) {
+        results.push(file);
+      }
+    }
+  }
+
+  return [...new Set(results)];
+}
+
+function findTsFiles(dir: string, files: string[] = []): string[] {
+  let entries: fs.Dirent[];
+  try {
+    entries = fs.readdirSync(dir, { withFileTypes: true });
+  } catch {
+    return files;
+  }
+
+  for (const entry of entries) {
+    const fullPath = path.join(dir, entry.name);
+    if (entry.isDirectory()) {
+      if (SKIP_DIRS.has(entry.name)) continue;
+      findTsFiles(fullPath, files);
+    } else if (entry.isFile() && entry.name.endsWith(".ts")) {
+      files.push(fullPath);
+    }
+  }
+
+  return files;
+}
+
+function isAlreadyMigrated(content: string): boolean {
+  const ast = parse(Lang.TypeScript, content);
+  const root = ast.root();
+  return root.findAll("createApp({ $$$PROPS })").some((match) => {
+    const text = match.text();
+    return /\bonPluginsReady\s*[(:]/.test(text);
+  });
+}
+
+/**
+ * Find the index of the matching closing delimiter for an opening one.
+ * Supports (), {}, and [].
+ */
+function findMatchingClose(content: string, openIdx: number): number {
+  const open = content[openIdx];
+  const closeMap: Record<string, string> = {
+    "(": ")",
+    "{": "}",
+    "[": "]",
+  };
+  const close = closeMap[open];
+  if (!close) return -1;
+
+  let depth = 1;
+  let i = openIdx + 1;
+  while (i < content.length && depth > 0) {
+    const ch = content[i];
+    if (ch === open) depth++;
+    else if (ch === close) depth--;
+
+    // skip string literals
+    if (ch === '"' || ch === "'" || ch === "`") {
+      i = skipString(content, i);
+      continue;
+    }
+    i++;
+  }
+  return depth === 0 ? i - 1 : -1;
+}
+
+function skipString(content: string, startIdx: number): number {
+  const quote = content[startIdx];
+  let i = startIdx + 1;
+  while (i < content.length) {
+    if (content[i] === "\\") {
+      i += 2;
+      continue;
+    }
+    if (content[i] === quote) return i + 1;
+    i++;
+  }
+  return i;
+}
+
+function stripAutoStartFromServerCalls(content: string): string {
+  return content.replace(
+    /server\(\{([^}]*)\}\)/g,
+    (_fullMatch, propsStr: string) => {
+      const cleaned = propsStr
+        .replace(/autoStart\s*:\s*(true|false)\s*,?\s*/g, "")
+        .replace(/,\s*$/, "")
+        .trim();
+      if (!cleaned) return "server()";
+      return `server({ ${cleaned} })`;
+    },
+  );
+}
+
+interface MigrationResult {
+  migrated: boolean;
+  content: string;
+  warnings: string[];
+}
+
+function migratePatternA(content: string): MigrationResult {
+  const warnings: string[] = [];
+
+  // Find createApp(...).then(
+  const createAppIdx = content.indexOf("createApp(");
+  if (createAppIdx === -1) return { migrated: false, content, warnings };
+
+  // Find the opening paren of createApp(
+  const configOpenParen = content.indexOf("(", createAppIdx);
+  const configCloseParen = findMatchingClose(content, configOpenParen);
+  if (configCloseParen === -1) return { migrated: false, content, warnings };
+
+  // Check for .then( after the closing paren
+  const afterCreateApp = content.slice(configCloseParen + 1);
+  const thenMatch = afterCreateApp.match(/^\s*\.then\s*\(/);
+  if (!thenMatch) return { migrated: false, content, warnings };
+
+  const thenStart = configCloseParen + 1 + afterCreateApp.indexOf(".then");
+  const thenOpenParen = content.indexOf("(", thenStart + 4);
+  const thenCloseParen = findMatchingClose(content, thenOpenParen);
+  if (thenCloseParen === -1) return { migrated: false, content, warnings };
+
+  // Extract the callback inside .then(...)
+  const thenRaw = content.slice(thenOpenParen + 1, thenCloseParen);
+  const thenInner = thenRaw.trim();
+
+  // Parse callback: (param) => { body } or async (param) => { body }
+  const callbackMatch = thenInner.match(
+    /^(?:async\s+)?\(\s*(\w+)\s*\)\s*=>\s*\{/,
+  );
+  if (!callbackMatch) return { migrated: false, content, warnings };
+
+  const paramName = callbackMatch[1];
+  const bodyOpenBrace = thenOpenParen + 1 + thenRaw.indexOf("{");
+  const bodyCloseBrace = findMatchingClose(content, bodyOpenBrace);
+  if (bodyCloseBrace === -1) return { migrated: false, content, warnings };
+
+  let callbackBody = content.slice(bodyOpenBrace + 1, bodyCloseBrace).trim();
+
+  // Remove .start() calls from the body
+  callbackBody = callbackBody
+    .replace(/\n\s*\.start\(\s*\)\s*;?/g, ";")
+    .replace(/\.start\(\s*\)/g, "")
+    .trim();
+
+  // Clean up trailing semicolons
+  if (callbackBody.endsWith(";")) {
+    // fine
+  } else if (!callbackBody.endsWith("}")) {
+    callbackBody += ";";
+  }
+
+  // Check for .catch() after .then(...) using brace-aware parsing
+  const afterThenClose = content.slice(thenCloseParen + 1);
+  const catchPatternMatch = afterThenClose.match(/^\s*(?:\)\s*)?\.catch\s*\(/);
+
+  let catchSuffix: string;
+  let consumeAfterThen: number;
+
+  if (catchPatternMatch) {
+    const catchOpenParen = thenCloseParen + 1 + catchPatternMatch[0].length - 1;
+    const catchCloseParen = findMatchingClose(content, catchOpenParen);
+    if (catchCloseParen !== -1) {
+      const catchArg = content
+        .slice(catchOpenParen + 1, catchCloseParen)
+        .trim();
+      catchSuffix = `.catch(${catchArg})`;
+      consumeAfterThen = catchCloseParen + 1 - (thenCloseParen + 1);
+    } else {
+      catchSuffix = ".catch(console.error)";
+      consumeAfterThen = 0;
+    }
+  } else {
+    catchSuffix = ".catch(console.error)";
+    consumeAfterThen = 0;
+  }
+
+  // Build the onPluginsReady property
+  const configStr = content.slice(configOpenParen + 1, configCloseParen);
+  const lastBraceIdx = configStr.lastIndexOf("}");
+  if (lastBraceIdx === -1) return { migrated: false, content, warnings };
+
+  const beforeLastBrace = configStr.slice(0, lastBraceIdx).trimEnd();
+  const needsComma = beforeLastBrace.endsWith(",") ? "" : ",";
+
+  // Indent the body properly
+  const bodyLines = callbackBody.split("\n");
+  const indentedBody = bodyLines
+    .map((line) => `    ${line.trimStart()}`)
+    .join("\n");
+
+  const onPluginsReadyProp = `${needsComma}\n  onPluginsReady(${paramName}) {\n${indentedBody}\n  },`;
+  const newConfig = `${beforeLastBrace}${onPluginsReadyProp}\n}`;
+
+  // Build the replacement
+  const endIdx = thenCloseParen + 1 + consumeAfterThen;
+  // Consume trailing ) ; and whitespace
+  let finalEnd = endIdx;
+  const trailing = content.slice(finalEnd).match(/^\s*\)?\s*;?\s*/);
+  if (trailing) finalEnd += trailing[0].length;
+
+  const newContent =
+    content.slice(0, createAppIdx) +
+    `createApp(${newConfig})${catchSuffix};` +
+    content.slice(finalEnd);
+
+  return { migrated: true, content: newContent, warnings };
+}
+
+function migratePatternB(content: string): MigrationResult {
+  const warnings: string[] = [];
+
+  // Match: const/let varName = await createApp({...});
+  const awaitPattern = /(?:const|let)\s+(\w+)\s*=\s*await\s+createApp\s*\(/;
+
+  const match = content.match(awaitPattern);
+  if (!match) return { migrated: false, content, warnings };
+
+  const varName = match[1];
+  const matchIdx = content.indexOf(match[0]);
+
+  // Find the createApp(...) closing paren
+  const configOpenParen = matchIdx + match[0].length - 1;
+  const configCloseParen = findMatchingClose(content, configOpenParen);
+  if (configCloseParen === -1) return { migrated: false, content, warnings };
+
+  // Find the semicolon after the createApp call
+  const afterCall = content.slice(configCloseParen + 1);
+  const semiMatch = afterCall.match(/^\s*;/);
+  const createAppEnd =
+    configCloseParen + 1 + (semiMatch ? semiMatch[0].length : 0);
+
+  // Find all uses of varName after the createApp call
+  const afterCreateApp = content.slice(createAppEnd);
+  const varUsagePattern = new RegExp(`\\b${varName}\\.(\\w+)`, "g");
+
+  const usages: { plugin: string; index: number }[] = [];
+  for (const usageMatch of afterCreateApp.matchAll(varUsagePattern)) {
+    usages.push({ plugin: usageMatch[1], index: usageMatch.index });
+  }
+
+  // Check for non-server usage
+  const nonServerUsage = usages.filter((u) => u.plugin !== "server");
+  if (nonServerUsage.length > 0) {
+    warnings.push(
+      `Found additional usage of '${varName}' handle outside server.extend/start. Please migrate manually.`,
+    );
+    return { migrated: false, content, warnings };
+  }
+
+  // Find the extend call(s) and start call in the after-createApp region
+  const extendPattern = new RegExp(
+    `\\b${varName}\\.server\\.extend\\s*\\(`,
+    "g",
+  );
+  const startPattern = new RegExp(
+    `(?:await\\s+)?${varName}\\.server\\.start\\s*\\(\\s*\\)\\s*;`,
+  );
+
+  const extendMatches = [...afterCreateApp.matchAll(extendPattern)];
+  if (extendMatches.length > 1) {
+    warnings.push(
+      `Found ${extendMatches.length} server.extend() calls. Please migrate manually.`,
+    );
+    return { migrated: false, content, warnings };
+  }
+
+  const extendExec = extendMatches[0] ?? null;
+  const startExec = startPattern.exec(afterCreateApp);
+
+  if (!startExec) return { migrated: false, content, warnings };
+
+  // Extract the extend call's argument
+  let extendArg = "";
+  let extendFullStatement = "";
+  if (extendExec) {
+    const extendOpenParen =
+      createAppEnd + extendExec.index + extendExec[0].length - 1;
+    const extendCloseParen = findMatchingClose(content, extendOpenParen);
+    if (extendCloseParen !== -1) {
+      extendArg = content.slice(extendOpenParen + 1, extendCloseParen).trim();
+      // Find the full statement including trailing semicolon
+      const stmtStart = createAppEnd + extendExec.index;
+      let stmtEnd = extendCloseParen + 1;
+      const afterExtend = content.slice(stmtEnd);
+      const trailingSemi = afterExtend.match(/^\s*;/);
+      if (trailingSemi) stmtEnd += trailingSemi[0].length;
+      extendFullStatement = content.slice(stmtStart, stmtEnd);
+    }
+  }
+
+  const startFullStatement = startExec[0];
+
+  // Build the onPluginsReady callback
+  const configStr = content.slice(configOpenParen + 1, configCloseParen);
+  const lastBraceIdx = configStr.lastIndexOf("}");
+  if (lastBraceIdx === -1) return { migrated: false, content, warnings };
+
+  const beforeLastBrace = configStr.slice(0, lastBraceIdx).trimEnd();
+  const needsComma = beforeLastBrace.endsWith(",") ? "" : ",";
+
+  let onPluginsReadyProp: string;
+  if (extendArg) {
+    onPluginsReadyProp =
+      `${needsComma}\n  onPluginsReady(${varName}) {\n` +
+      `    ${varName}.server.extend(${extendArg});\n` +
+      "  },";
+  } else {
+    onPluginsReadyProp = "";
+  }
+
+  const newConfig = `${beforeLastBrace}${onPluginsReadyProp}\n}`;
+  const newCreateApp = `await createApp(${newConfig});`;
+
+  // Replace: remove const declaration, replace with plain await, remove extend + start
+  let result = content.slice(0, matchIdx) + newCreateApp;
+  let remaining = afterCreateApp;
+
+  if (extendFullStatement) {
+    remaining = remaining.replace(extendFullStatement, "");
+  }
+  remaining = remaining.replace(startFullStatement, "");
+
+  // Clean up consecutive blank lines
+  remaining = remaining.replace(/\n\s*\n\s*\n/g, "\n\n");
+
+  result += remaining;
+
+  return { migrated: true, content: result, warnings };
+}
+
+export function migrateFile(filePath: string): MigrationResult {
+  const original = fs.readFileSync(filePath, "utf-8");
+
+  if (isAlreadyMigrated(original)) {
+    return {
+      migrated: false,
+      content: original,
+      warnings: ["Already migrated -- no changes needed."],
+    };
+  }
+
+  const content = stripAutoStartFromServerCalls(original);
+  const allWarnings: string[] = [];
+
+  // Try Pattern A first
+  const patternA = migratePatternA(content);
+  if (patternA.migrated) {
+    allWarnings.push(...patternA.warnings);
+    return {
+      migrated: true,
+      content: patternA.content,
+      warnings: allWarnings,
+    };
+  }
+  allWarnings.push(...patternA.warnings);
+
+  // Try Pattern B
+  const patternB = migratePatternB(content);
+  if (patternB.migrated) {
+    allWarnings.push(...patternB.warnings);
+    return {
+      migrated: true,
+      content: patternB.content,
+      warnings: allWarnings,
+    };
+  }
+  allWarnings.push(...patternB.warnings);
+
+  // Check if autoStart was stripped (content changed but no pattern matched)
+  if (content !== original) {
+    return { migrated: true, content, warnings: allWarnings };
+  }
+
+  return { migrated: false, content: original, warnings: allWarnings };
+}
+
+function runCodemod(options: { path?: string; write?: boolean }) {
+  const rootDir = process.cwd();
+  const write = options.write ?? false;
+
+  let files: string[];
+  if (options.path) {
+    const absPath = path.resolve(rootDir, options.path);
+    if (!fs.existsSync(absPath)) {
+      console.error(`File not found: ${absPath}`);
+      process.exit(1);
+    }
+    files = [absPath];
+  } else {
+    files = findServerEntryFiles(rootDir);
+  }
+
+  if (files.length === 0) {
+    console.log("No files found importing createApp from @databricks/appkit.");
+    console.log("Use --path to specify a file explicitly.");
+    process.exit(0);
+  }
+
+  let hasChanges = false;
+
+  for (const file of files) {
+    const relPath = path.relative(rootDir, file);
+    const result = migrateFile(file);
+
+    for (const warning of result.warnings) {
+      console.log(`  ${relPath}: ${warning}`);
+    }
+
+    if (!result.migrated) {
+      if (result.warnings.length === 0) {
+        console.log(`  ${relPath}: No migration needed.`);
+      }
+      continue;
+    }
+
+    hasChanges = true;
+
+    if (write) {
+      fs.writeFileSync(file, result.content, "utf-8");
+      console.log(`  ${relPath}: Migrated successfully.`);
+    } else {
+      console.log(`\n--- ${relPath} (dry run) ---`);
+      console.log(result.content);
+      console.log("---");
+    }
+  }
+
+  if (hasChanges && !write) {
+    console.log("\nDry run complete. Run with --write to apply changes.");
+  }
+}
+
+export const customizeCallbackCommand = new Command("customize-callback")
+  .description(
+    "Migrate createApp usage from autoStart/extend/start pattern to onPluginsReady callback (formerly customize)",
+  )
+  .option("--path <file>", "Path to the server entry file to migrate")
+  .option("--write", "Apply changes (default: dry-run)", false)
+  .addHelpText(
+    "after",
+    `
+Examples:
+  $ appkit codemod customize-callback                    # dry-run, auto-detect files
+  $ appkit codemod customize-callback --write            # apply changes
+  $ appkit codemod customize-callback --path server.ts   # migrate a specific file`,
+  )
+  .action(runCodemod);
diff --git a/packages/shared/src/cli/commands/codemod/index.ts b/packages/shared/src/cli/commands/codemod/index.ts
new file mode 100644
index 00000000..0574427a
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/index.ts
@@ -0,0 +1,17 @@
+import { Command } from "commander";
+import { customizeCallbackCommand } from "./customize-callback";
+
+/**
+ * Parent command for codemod operations.
+ * Subcommands:
+ *   - customize-callback: Migrate from autoStart/extend/start to onPluginsReady callback
+ */
+export const codemodCommand = new Command("codemod")
+  .description("Run codemods to migrate to newer AppKit APIs")
+  .addCommand(customizeCallbackCommand)
+  .addHelpText(
+    "after",
+    `
+Examples:
+  $ appkit codemod customize-callback --write`,
+  );
diff --git a/packages/shared/src/cli/commands/codemod/tests/customize-callback.test.ts b/packages/shared/src/cli/commands/codemod/tests/customize-callback.test.ts
new file mode 100644
index 00000000..fc2c6e92
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/customize-callback.test.ts
@@ -0,0 +1,129 @@
+import fs from "node:fs";
+import path from "node:path";
+import { describe, expect, test } from "vitest";
+import { migrateFile } from "../customize-callback";
+
+const fixturesDir = path.join(__dirname, "fixtures");
+
+function readFixture(name: string): string {
+  return fs.readFileSync(path.join(fixturesDir, name), "utf-8");
+}
+
+describe("onPluginsReady-callback codemod", () => {
+  describe("Pattern A: .then() chain", () => {
+    test("migrates .then chain without .catch, adds .catch(console.error)", () => {
+      const fixturePath = path.join(fixturesDir, "pattern-a.input.ts");
+      const result = migrateFile(fixturePath);
+
+      expect(result.migrated).toBe(true);
+      expect(result.content).toContain("onPluginsReady(appkit)");
+      expect(result.content).not.toContain(".then(");
+      expect(result.content).not.toContain(".start()");
+      expect(result.content).not.toContain("autoStart");
+      expect(result.content).toContain(".catch(console.error)");
+      expect(result.content).toContain("server()");
+    });
+
+    test("migrates .then chain with existing .catch, preserves it", () => {
+      const fixturePath = path.join(
+        fixturesDir,
+        "pattern-a-with-catch.input.ts",
+      );
+      const result = migrateFile(fixturePath);
+
+      expect(result.migrated).toBe(true);
+      expect(result.content).toContain("onPluginsReady(appkit)");
+      expect(result.content).not.toContain(".then(");
+      expect(result.content).not.toContain(".start()");
+      expect(result.content).toContain(".catch(console.error)");
+      expect(result.content).toContain("server()");
+    });
+
+    test("preserves the extend callback content", () => {
+      const fixturePath = path.join(fixturesDir, "pattern-a.input.ts");
+      const result = migrateFile(fixturePath);
+
+      expect(result.content).toContain('app.get("/custom"');
+      expect(result.content).toContain("res.json({ ok: true })");
+    });
+
+    test("preserves arrow function .catch handler with parens", () => {
+      const fixturePath = path.join(
+        fixturesDir,
+        "pattern-a-arrow-catch.input.ts",
+      );
+      const result = migrateFile(fixturePath);
+
+      expect(result.migrated).toBe(true);
+      expect(result.content).toContain(".catch((err) => console.error(err))");
+      expect(result.content).not.toContain(".then(");
+      expect(result.content).not.toContain(".start()");
+    });
+  });
+
+  describe("Pattern B: await + imperative", () => {
+    test("migrates await pattern with extend + start", () => {
+      const fixturePath = path.join(fixturesDir, "pattern-b.input.ts");
+      const result = migrateFile(fixturePath);
+
+      expect(result.migrated).toBe(true);
+      expect(result.content).toContain("onPluginsReady(appkit)");
+      expect(result.content).not.toContain("appkit.server.start()");
+      expect(result.content).not.toContain("autoStart");
+      expect(result.content).toContain("server()");
+    });
+
+    test("bails out when non-server usage of appkit handle exists", () => {
+      const fixturePath = path.join(fixturesDir, "pattern-b-complex.input.ts");
+      const result = migrateFile(fixturePath);
+
+      expect(result.warnings.some((w) => w.includes("migrate manually"))).toBe(
+        true,
+      );
+      expect(result.content).toContain("server()");
+      expect(result.content).not.toContain("autoStart");
+    });
+
+    test("bails out when multiple .extend() calls exist", () => {
+      const fixturePath = path.join(
+        fixturesDir,
+        "pattern-b-multi-extend.input.ts",
+      );
+      const result = migrateFile(fixturePath);
+
+      expect(result.warnings.some((w) => w.includes("migrate manually"))).toBe(
+        true,
+      );
+      expect(result.content).toContain("server()");
+      expect(result.content).not.toContain("autoStart");
+    });
+  });
+
+  describe("autoStart stripping", () => {
+    test("strips autoStart: true and preserves other config", () => {
+      const fixturePath = path.join(
+        fixturesDir,
+        "autostart-true-with-port.input.ts",
+      );
+      const result = migrateFile(fixturePath);
+
+      expect(result.migrated).toBe(true);
+      expect(result.content).not.toContain("autoStart");
+      expect(result.content).toContain("port: 3000");
+      expect(result.content).toContain("server({");
+    });
+  });
+
+  describe("idempotency", () => {
+    test("no-ops on already migrated file", () => {
+      const fixturePath = path.join(fixturesDir, "already-migrated.input.ts");
+      const result = migrateFile(fixturePath);
+
+      expect(result.migrated).toBe(false);
+      expect(result.warnings.some((w) => w.includes("Already migrated"))).toBe(
+        true,
+      );
+      expect(result.content).toBe(readFixture("already-migrated.input.ts"));
+    });
+  });
+});
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/already-migrated.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/already-migrated.input.ts
new file mode 100644
index 00000000..ab1cf6d0
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/already-migrated.input.ts
@@ -0,0 +1,10 @@
+import { analytics, createApp, server } from "@databricks/appkit";
+
+createApp({
+  plugins: [server(), analytics({})],
+  onPluginsReady(appkit) {
+    appkit.server.extend((app) => {
+      app.get("/custom", (_req, res) => res.json({ ok: true }));
+    });
+  },
+}).catch(console.error);
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/autostart-true-with-port.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/autostart-true-with-port.input.ts
new file mode 100644
index 00000000..96b70a4f
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/autostart-true-with-port.input.ts
@@ -0,0 +1,5 @@
+import { createApp, server } from "@databricks/appkit";
+
+createApp({
+  plugins: [server({ autoStart: true, port: 3000 })],
+}).catch(console.error);
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a-arrow-catch.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a-arrow-catch.input.ts
new file mode 100644
index 00000000..b6ae8c8a
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a-arrow-catch.input.ts
@@ -0,0 +1,15 @@
+import { analytics, createApp, server } from "@databricks/appkit";
+
+createApp({
+  plugins: [server({ autoStart: false }), analytics({})],
+})
+  .then((appkit) => {
+    appkit.server
+      .extend((app) => {
+        app.get("/custom", (_req, res) => {
+          res.json({ ok: true });
+        });
+      })
+      .start();
+  })
+  .catch((err) => console.error(err));
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a-with-catch.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a-with-catch.input.ts
new file mode 100644
index 00000000..faa04d5e
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a-with-catch.input.ts
@@ -0,0 +1,15 @@
+import { analytics, createApp, server } from "@databricks/appkit";
+
+createApp({
+  plugins: [server({ autoStart: false }), analytics({})],
+})
+  .then((appkit) => {
+    appkit.server
+      .extend((app) => {
+        app.get("/custom", (_req, res) => {
+          res.json({ ok: true });
+        });
+      })
+      .start();
+  })
+  .catch(console.error);
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a.input.ts
new file mode 100644
index 00000000..73523d6a
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-a.input.ts
@@ -0,0 +1,13 @@
+import { analytics, createApp, server } from "@databricks/appkit";
+
+createApp({
+  plugins: [server({ autoStart: false }), analytics({})],
+}).then((appkit) => {
+  appkit.server
+    .extend((app) => {
+      app.get("/custom", (_req, res) => {
+        res.json({ ok: true });
+      });
+    })
+    .start();
+});
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b-complex.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b-complex.input.ts
new file mode 100644
index 00000000..c1fb25fa
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b-complex.input.ts
@@ -0,0 +1,15 @@
+import { analytics, createApp, server } from "@databricks/appkit";
+
+const appkit = await createApp({
+  plugins: [server({ autoStart: false }), analytics({})],
+});
+
+appkit.server.extend((app) => {
+  app.get("/custom", (_req, res) => {
+    res.json({ ok: true });
+  });
+});
+
+appkit.analytics.query("SELECT 1");
+
+await appkit.server.start();
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b-multi-extend.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b-multi-extend.input.ts
new file mode 100644
index 00000000..dded09f2
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b-multi-extend.input.ts
@@ -0,0 +1,15 @@
+import { analytics, createApp, server } from "@databricks/appkit";
+
+const appkit = await createApp({
+  plugins: [server({ autoStart: false }), analytics({})],
+});
+
+appkit.server.extend((app) => {
+  app.get("/one", (_req, res) => res.json({ route: 1 }));
+});
+
+appkit.server.extend((app) => {
+  app.get("/two", (_req, res) => res.json({ route: 2 }));
+});
+
+await appkit.server.start();
diff --git a/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b.input.ts b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b.input.ts
new file mode 100644
index 00000000..b56c0048
--- /dev/null
+++ b/packages/shared/src/cli/commands/codemod/tests/fixtures/pattern-b.input.ts
@@ -0,0 +1,13 @@
+import { analytics, createApp, server } from "@databricks/appkit";
+
+const appkit = await createApp({
+  plugins: [server({ autoStart: false }), analytics({})],
+});
+
+appkit.server.extend((app) => {
+  app.get("/custom", (_req, res) => {
+    res.json({ ok: true });
+  });
+});
+
+await appkit.server.start();
diff --git a/packages/shared/src/cli/index.ts b/packages/shared/src/cli/index.ts
index 71f09e6f..4d0ed65b 100644
--- a/packages/shared/src/cli/index.ts
+++ b/packages/shared/src/cli/index.ts
@@ -4,6 +4,7 @@ import { readFileSync } from "node:fs";
 import { dirname, join } from "node:path";
 import { fileURLToPath } from "node:url";
 import { Command } from "commander";
+import { codemodCommand } from "./commands/codemod/index.js";
 import { docsCommand } from "./commands/docs.js";
 import { generateTypesCommand } from "./commands/generate-types.js";
 import { lintCommand } from "./commands/lint.js";
@@ -26,5 +27,6 @@ cmd.addCommand(generateTypesCommand);
 cmd.addCommand(lintCommand);
 cmd.addCommand(docsCommand);
 cmd.addCommand(pluginCommand);
+cmd.addCommand(codemodCommand);
 
 cmd.parse();
diff --git a/packages/shared/tsconfig.json b/packages/shared/tsconfig.json
index 4a6e68b3..5e195c3b 100644
--- a/packages/shared/tsconfig.json
+++ b/packages/shared/tsconfig.json
@@ -8,5 +8,5 @@
     }
   },
   "include": ["src/**/*"],
-  "exclude": ["node_modules", "dist"]
+  "exclude": ["node_modules", "dist", "src/**/fixtures"]
 }
diff --git a/template/server/server.ts b/template/server/server.ts
index 214ac1ce..e28f3ef4 100644
--- a/template/server/server.ts
+++ b/template/server/server.ts
@@ -5,24 +5,13 @@ import { setupSampleLakebaseRoutes } from './routes/lakebase/todo-routes';
 
 createApp({
   plugins: [
-{{- if .plugins.lakebase}}
-    server({ autoStart: false }),
-{{- range $name, $_ := .plugins}}
-{{- if ne $name "server"}}
-    {{$name}}(),
-{{- end}}
-{{- end}}
-{{- else}}
 {{- range $name, $_ := .plugins}}
     {{$name}}(),
-{{- end}}
 {{- end}}
   ],
-})
 {{- if .plugins.lakebase}}
-  .then(async (appkit) => {
+  async onPluginsReady(appkit) {
     await setupSampleLakebaseRoutes(appkit);
-    await appkit.server.start();
-  })
+  },
 {{- end}}
-  .catch(console.error);
+}).catch(console.error);