diff --git a/packages/adapters/hono/src/index.ts b/packages/adapters/hono/src/index.ts
index 58178e676a..63dbd4664a 100644
--- a/packages/adapters/hono/src/index.ts
+++ b/packages/adapters/hono/src/index.ts
@@ -9,6 +9,13 @@ export interface ObjectStackHonoOptions {
   prefix?: string;
 }
 
+/**
+ * Auth service interface with handleRequest method
+ */
+interface AuthService {
+  handleRequest(request: Request): Promise<Response>;
+}
+
 /**
  * @deprecated Use `HonoServerPlugin` + `createRestApiPlugin()` + `createDispatcherPlugin()` instead.
  * This function bundles all routes into a single Hono app using the legacy HttpDispatcher.
@@ -68,7 +75,7 @@ export function createHonoApp(options: ObjectStackHonoOptions) {
     try {
       // Try AuthPlugin service first (preferred path)
       const authService = typeof options.kernel.getService === 'function'
-        ? options.kernel.getService('auth')
+        ? options.kernel.getService<AuthService>('auth')
         : null;
 
       if (authService && typeof authService.handleRequest === 'function') {
diff --git a/packages/adapters/nestjs/src/index.ts b/packages/adapters/nestjs/src/index.ts
index de741e6a9a..4acd9f4568 100644
--- a/packages/adapters/nestjs/src/index.ts
+++ b/packages/adapters/nestjs/src/index.ts
@@ -12,6 +12,13 @@ export const ConnectReq = createParamDecorator(
   },
 );
 
+/**
+ * Auth service interface with handleRequest method
+ */
+interface AuthService {
+  handleRequest(request: Request): Promise<Response>;
+}
+
 // --- Service ---
 
 @Injectable()
@@ -109,7 +116,7 @@ export class ObjectStackController {
         // Try AuthPlugin service first (preferred path)
         const kernel = this.service.getKernel();
         const authService = typeof kernel.getService === 'function'
-          ? kernel.getService('auth')
+          ? kernel.getService<AuthService>('auth')
           : null;
 
         if (authService && typeof authService.handleRequest === 'function') {
diff --git a/packages/adapters/nextjs/src/index.ts b/packages/adapters/nextjs/src/index.ts
index efb5e47c64..51e42abc34 100644
--- a/packages/adapters/nextjs/src/index.ts
+++ b/packages/adapters/nextjs/src/index.ts
@@ -8,6 +8,13 @@ export interface NextAdapterOptions {
   prefix?: string;
 }
 
+/**
+ * Auth service interface with handleRequest method
+ */
+interface AuthService {
+  handleRequest(request: Request): Promise<Response>;
+}
+
 /**
  * Creates a route handler for Next.js App Router
  * Handles /api/[...objectstack] pattern
@@ -63,7 +70,7 @@ export function createRouteHandler(options: NextAdapterOptions) {
         if (segments[0] === 'auth') {
            // Try AuthPlugin service first (preferred path)
            const authService = typeof options.kernel.getService === 'function'
-             ? options.kernel.getService('auth')
+             ? options.kernel.getService<AuthService>('auth')
              : null;
 
            if (authService && typeof authService.handleRequest === 'function') {