diff --git a/crates/mesh-llm-ui/src/features/chat/api/build-input.test.ts b/crates/mesh-llm-ui/src/features/chat/api/build-input.test.ts
index 12245f7e86..852e7ac7e2 100644
--- a/crates/mesh-llm-ui/src/features/chat/api/build-input.test.ts
+++ b/crates/mesh-llm-ui/src/features/chat/api/build-input.test.ts
@@ -88,6 +88,18 @@ describe('buildResponsesInput', () => {
     expect(request.input).toEqual([{ role: 'user', content: 'Hello mesh' }])
   })
 
+  it('asks for minimal reasoning effort', async () => {
+    const request = await buildResponsesInput(
+      [createMessage([{ type: 'text', content: 'what is updog' }])],
+      'model-a',
+      'client-123',
+      'request-456'
+    )
+
+    expect(request.reasoning_effort).toBe('minimal')
+    expect(request).not.toHaveProperty('chat_template_kwargs')
+  })
+
   it('prepends the saved system prompt as a responses system message', async () => {
     const request = await buildResponsesInput(
       [createMessage([{ type: 'text', content: 'Explain the cluster status' }])],
diff --git a/crates/mesh-llm-ui/src/features/chat/api/build-input.ts b/crates/mesh-llm-ui/src/features/chat/api/build-input.ts
index 066d06fc6d..32e084445e 100644
--- a/crates/mesh-llm-ui/src/features/chat/api/build-input.ts
+++ b/crates/mesh-llm-ui/src/features/chat/api/build-input.ts
@@ -186,6 +186,11 @@ export async function buildResponsesInput(
     request_id: requestId,
     input: messagesWithSystemPrompt,
     stream: true,
-    stream_options: { include_usage: true }
+    stream_options: { include_usage: true },
+    // Reasoning models deliberate for tens of seconds over a casual question
+    // when nothing asks them not to. The console keeps thinking -- it renders
+    // the trace -- but asks for the least of it. API callers are unaffected:
+    // they choose their own reasoning controls.
+    reasoning_effort: 'minimal'
   }
 }
diff --git a/crates/mesh-llm-ui/src/lib/api/types.ts b/crates/mesh-llm-ui/src/lib/api/types.ts
index 18f51e6193..a16a19b6af 100644
--- a/crates/mesh-llm-ui/src/lib/api/types.ts
+++ b/crates/mesh-llm-ui/src/lib/api/types.ts
@@ -301,6 +301,7 @@ export interface ResponsesRequest {
   input: ResponsesInputMessage[]
   stream: boolean
   stream_options?: { include_usage: boolean }
+  reasoning_effort?: 'none' | 'minimal' | 'low' | 'medium' | 'high' | 'xhigh' | 'max'
 }
 
 export interface ChatSSEDeltaEvent {