🔥(chat) remove thinking part from frontend

We want to enable the OSS model but seems like it returns
thinking values twice and we don't manage it well...

So we disable the frontend while we still don't know
how to display the thinking stuff.
We could have also cleaned the backend while unused.

CHANGELOG.md

@@ -18,6 +18,10 @@ and this project adheres to
 - 🐛(back) fix system prompt compatibility with self-hosted models #200
 - ⚰️(back) remove dead code and unused files
 
+### Removed
+
+- 🔥(chat) remove thinking part from frontend #227
+
 ## [0.0.10] - 2025-12-15
 
 ### Added

src/frontend/apps/conversations/src/features/chat/components/Chat.tsx

@@ -1,9 +1,4 @@
-import {
-  Message,
-  ReasoningUIPart,
-  SourceUIPart,
-  ToolInvocationUIPart,
-} from '@ai-sdk/ui-utils';
+import { Message, SourceUIPart, ToolInvocationUIPart } from '@ai-sdk/ui-utils';
 import { Modal, ModalSize } from '@openfun/cunningham-react';
 import 'katex/dist/katex.min.css'; // `rehype-katex` does not import the CSS for you
 import { useRouter } from 'next/router';
@@ -816,30 +811,12 @@ export const Chat = ({
                             </Box>
                           )}
                         {message.parts
-                          ?.filter(
-                            (part) =>
-                              part.type === 'reasoning' ||
-                              part.type === 'tool-invocation',
-                          )
+                          ?.filter((part) => part.type === 'tool-invocation')
                           .map(
-                            (
-                              part: ReasoningUIPart | ToolInvocationUIPart,
-                              partIndex: number,
-                            ) =>
-                              part.type === 'reasoning' ? (
-                                <Box
-                                  key={`reasoning-${partIndex}`}
-                                  $background="var(--c--theme--colors--greyscale-100)"
-                                  $color="var(--c--theme--colors--greyscale-500)"
-                                  $padding={{ all: 'sm' }}
-                                  $radius="md"
-                                  $css="font-size: 0.9em;"
-                                >
-                                  {part.reasoning}
-                                </Box>
-                              ) : part.type === 'tool-invocation' &&
-                                isCurrentlyStreaming &&
-                                isLastAssistantMessageInConversation ? (
+                            (part: ToolInvocationUIPart, partIndex: number) =>
+                              part.type === 'tool-invocation' &&
+                              isCurrentlyStreaming &&
+                              isLastAssistantMessageInConversation ? (
                                 <ToolInvocationItem
                                   key={`tool-invocation-${partIndex}`}
                                   toolInvocation={part.toolInvocation}

src/frontend/apps/e2e/__tests__/app-conversations/chat.spec.ts

@@ -52,7 +52,7 @@ test.describe('Chat page', () => {
 
     const messageContent = page.getByTestId('assistant-message-content');
     await expect(messageContent).toBeVisible();
-    await expect(messageContent).not.toBeEmpty(); 
+    await expect(messageContent).not.toBeEmpty();
 
     // Check history
     const chatHistoryLink = page