feat: stream pattern events to console behind a feature flag

components/message.tsx

@@ -15,7 +15,6 @@ import { DocumentToolCall, DocumentToolResult } from './document';
 import { DocumentPreview } from './document-preview';
 import { Markdown } from './markdown';
 import { MessageEditor } from './message-editor';
-import { MessageReasoning } from './message-reasoning';
 import { PreviewAttachment } from './preview-attachment';
 import { Weather } from './weather';
 
@@ -42,6 +41,13 @@ const PurePreviewMessage = ({
 }) => {
   const [mode, setMode] = useState<'view' | 'edit'>('view');
 
+  /**
+   * For now, only streaming reasoning to console is supported
+   */
+  if (message.reasoning) {
+    console.log('Pattern event: ', message.reasoning);
+  }
+
   return (
     <AnimatePresence>
       <motion.div
@@ -86,13 +92,6 @@ const PurePreviewMessage = ({
               </div>
             )}
 
-            {message.reasoning && (
-              <MessageReasoning
-                isLoading={isLoading}
-                reasoning={message.reasoning}
-              />
-            )}
-
             {(message.content || message.reasoning) && mode === 'view' && (
               <div className="flex flex-row gap-2 items-start">
                 <div

lib/ai/pattern-model.ts

@@ -11,6 +11,7 @@ import type {
   ToolStartEvent,
 } from '@/lib/ai/types';
 
+import { showToolCalls as showToolCallsFlag } from '../flags';
 import { extractErrorMessageOrDefault } from '../utils';
 
 const textDecoder = new TextDecoder();
@@ -85,7 +86,10 @@ export class PatternModel implements LanguageModelV1 {
     let incompleteJsonFragment = '';
 
     return new TransformStream<string, LanguageModelV1StreamPart>({
-      transform: (chunk, controller) => {
+      transform: async (chunk, controller) => {
+        const showToolCalls = await showToolCallsFlag();
+        const shouldStreamToolCalls = showToolCalls === 'console';
+
         if (ArrayBuffer.isView(chunk)) {
           try {
             const chunkBuffer = new Uint8Array(
@@ -160,10 +164,12 @@ export class PatternModel implements LanguageModelV1 {
                   textDelta: event.data,
                 });
               } else if (SUPPORTED_EVENT_TYPES.includes(event.type)) {
-                /**
-                 * TODO: Re-enable reasoning when backend supports it
-                 * https://github.com/pattern-tech/pattern-app/issues/27
-                 */
+                if (shouldStreamToolCalls) {
+                  controller.enqueue({
+                    type: 'reasoning',
+                    textDelta: JSON.stringify(event),
+                  });
+                }
               } else {
                 controller.enqueue({
                   type: 'error',

lib/flags.ts

@@ -8,3 +8,14 @@ import { flag } from 'flags/next';
  *   key: 'some-flag',
  * });
  */
+
+/**
+ * Feature flag to control whether to show tool calls in the chat UI
+ */
+type ShowToolCalls = 'console' | undefined;
+export const showToolCalls = flag<ShowToolCalls>({
+  adapter: edgeConfigAdapter(),
+  key: 'show-tool-calls',
+  options: ['console'],
+  defaultValue: undefined,
+});