diff --git a/packages/agent/src/routes/index.ts b/packages/agent/src/routes/index.ts
index 6d626180e2..39c748581c 100644
--- a/packages/agent/src/routes/index.ts
+++ b/packages/agent/src/routes/index.ts
@@ -174,8 +174,8 @@ function getAiRoutes(options: Options, services: Services, aiRouter: AiRouter |
 }
 
 function getWorkflowExecutorRoutes(options: Options, services: Services): BaseRoute[] {
-  if (!options.workflowExecutorUrl) return [];
-
+  // Always mount the route so that hitting it without `workflowExecutorUrl` configured
+  // returns an explicit error to the client instead of a bare 404.
   return [new WorkflowExecutorProxyRoute(services, options)];
 }
 
diff --git a/packages/agent/src/routes/workflow/workflow-executor-proxy.ts b/packages/agent/src/routes/workflow/workflow-executor-proxy.ts
index 0fc391cffe..f45c35598a 100644
--- a/packages/agent/src/routes/workflow/workflow-executor-proxy.ts
+++ b/packages/agent/src/routes/workflow/workflow-executor-proxy.ts
@@ -3,6 +3,7 @@ import type { AgentOptionsWithDefaults } from '../../types';
 import type KoaRouter from '@koa/router';
 import type { Context } from 'koa';
 
+import { InternalServerError } from '@forestadmin/datasource-toolkit';
 import { request as httpRequest } from 'http';
 import { request as httpsRequest } from 'https';
 
@@ -16,12 +17,14 @@ type ForwardedHeaders = {
 
 export default class WorkflowExecutorProxyRoute extends BaseRoute {
   readonly type = RouteType.PrivateRoute;
-  private readonly executorUrl: URL;
+  private readonly executorUrl: URL | null;
 
   constructor(services: ForestAdminHttpDriverServices, options: AgentOptionsWithDefaults) {
     super(services, options);
     // Remove trailing slash for clean URL joining
-    this.executorUrl = new URL(options.workflowExecutorUrl.replace(/\/+$/, ''));
+    this.executorUrl = options.workflowExecutorUrl
+      ? new URL(options.workflowExecutorUrl.replace(/\/+$/, ''))
+      : null;
   }
 
   setupRoutes(router: KoaRouter): void {
@@ -30,6 +33,12 @@ export default class WorkflowExecutorProxyRoute extends BaseRoute {
   }
 
   private async handleProxy(context: Context): Promise<void> {
+    if (!this.executorUrl) {
+      throw new InternalServerError(
+        'The workflow executor is not configured on this agent: the `workflowExecutorUrl` option is missing.',
+      );
+    }
+
     const { runId } = context.params;
     const isTrigger = context.method === 'POST';
     const qs = context.querystring ? `?${context.querystring}` : '';
diff --git a/packages/agent/test/routes/index.test.ts b/packages/agent/test/routes/index.test.ts
index d2e56b8ddb..263856ffba 100644
--- a/packages/agent/test/routes/index.test.ts
+++ b/packages/agent/test/routes/index.test.ts
@@ -68,8 +68,12 @@ describe('Route index', () => {
     expect(NATIVE_QUERY_ROUTES_CTOR).toEqual([DataSourceNativeQueryRoute]);
   });
 
+  const WORKFLOW_EXECUTOR_ROUTE_SIZE = 1;
   const BASE_ROUTE_SIZE =
-    ROOT_ROUTES_CTOR.length + CAPABILITIES_ROUTES_CTOR.length + NATIVE_QUERY_ROUTES_CTOR.length;
+    ROOT_ROUTES_CTOR.length +
+    CAPABILITIES_ROUTES_CTOR.length +
+    NATIVE_QUERY_ROUTES_CTOR.length +
+    WORKFLOW_EXECUTOR_ROUTE_SIZE;
 
   describe('makeRoutes', () => {
     describe('when a data source without relations', () => {
diff --git a/packages/agent/test/routes/workflow/workflow-executor-proxy.test.ts b/packages/agent/test/routes/workflow/workflow-executor-proxy.test.ts
index d5cbad16b1..9d279b3412 100644
--- a/packages/agent/test/routes/workflow/workflow-executor-proxy.test.ts
+++ b/packages/agent/test/routes/workflow/workflow-executor-proxy.test.ts
@@ -73,6 +73,16 @@ describe('WorkflowExecutorProxyRoute', () => {
 
       expect(route.type).toBe(RouteType.PrivateRoute);
     });
+
+    test('should not throw when workflowExecutorUrl is not configured', () => {
+      expect(
+        () =>
+          new WorkflowExecutorProxyRoute(
+            services,
+            factories.forestAdminHttpDriverOptions.build({ workflowExecutorUrl: null }),
+          ),
+      ).not.toThrow();
+    });
   });
 
   describe('setupRoutes', () => {
@@ -224,6 +234,24 @@ describe('WorkflowExecutorProxyRoute', () => {
       ).rejects.toThrow();
     });
 
+    test('should throw an explicit error when workflowExecutorUrl is not configured', async () => {
+      const route = new WorkflowExecutorProxyRoute(
+        services,
+        factories.forestAdminHttpDriverOptions.build({ workflowExecutorUrl: null }),
+      );
+
+      const context = createMockContext({
+        customProperties: { params: { runId: 'run-123' } },
+      });
+      Object.defineProperty(context, 'url', {
+        value: '/_internal/workflow-executions/run-123',
+      });
+
+      await expect(
+        (route as unknown as { handleProxy: (ctx: unknown) => Promise<void> }).handleProxy(context),
+      ).rejects.toThrow('The workflow executor is not configured on this agent');
+    });
+
     test('should forward query params to the executor', async () => {
       const route = new WorkflowExecutorProxyRoute(
         services,