draw a diagram in tutor answers: validated JSON from the model, rendered by the app; add the fourth companion tedi

The model ends a shape question with <diagram>{json}</diagram>; rag/services/diagram.py
splits it off before mathtext, validates it against a whitelist and stores it on
Message.diagram (ai_tutor.0006). It reaches the app in the SSE done event and in
conversation history. Prompt tutor-v6-diagrams; a hint next to the question (shape
words only) raised gpt-4.1-mini from 3/12 to 12/12 diagrams, 0/8 on arithmetic.

progress.0005 adds tedi (600 xp) to the companion catalog.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ai_tutor/views.py

@@ -54,6 +54,8 @@ def _annotation(retrieval_meta: dict, generation_meta: dict, *, from_cache: bool
         'completion_tokens': int(generation_meta.get('completionTokens') or 0),
         'latency_ms': int(generation_meta.get('latencyMs') or 0),
         'from_cache': bool(from_cache),
+        # شکلِ اعتبارسنجی‌شده در rag.services.diagram؛ کشِ قدیمی آن را ندارد.
+        'diagram': generation_meta.get('diagram') if isinstance(generation_meta.get('diagram'), dict) else None,
     }
 
 
@@ -461,6 +463,7 @@ class AskAIView(APIView):
             'answer': answer_text,
             'suggestedFollowUps': follow_ups,
             'remainingQuota': remaining_quota,
+            'diagram': assistant_message.diagram,
             'usedChunks': [
                 {'title': c.get('title', ''), 'summary': c.get('summary', '')}
                 for c in used_chunks
@@ -486,7 +489,7 @@ class AskAIView(APIView):
         نسخه‌ی SSE از post(): همون منطقِ retrieval + کوتا + idempotency، ولی
         پاسخ توکن‌به‌توکن استریم می‌شه. رویدادها:
           event: chunk  data: {"delta": "..."}
-          event: done   data: {conversationId, messageId, remainingQuota, usedChunks[, retrievalDebug]}
+          event: done   data: {conversationId, messageId, remainingQuota, diagram, usedChunks[, retrievalDebug]}
           event: error  data: {"detail": "..."}
         فاز ۱ (رزرو کوتا + conversation + user_message) قبلاً در post() انجام شده.
         """
@@ -529,11 +532,12 @@ class AskAIView(APIView):
                         for c in used_chunks
                     ]
                     parts: list[str] = []
+                    stream_result: dict = {}
                     started = time.monotonic()
                     effective_grade = retrieval_meta.get('gradeTitle') or grade_title or ''
                     for delta in stream_answer(
                         v['userQuestion'], used_chunks or None, effective_grade,
-                        history=history, focus=focus,
+                        history=history, focus=focus, result=stream_result,
                     ):
                         parts.append(delta)
                         yield _sse('chunk', {'delta': delta})
@@ -548,6 +552,7 @@ class AskAIView(APIView):
                         'promptVersion': PROMPT_VERSION,
                         'latencyMs': int((time.monotonic() - started) * 1000),
                         'hadContext': bool(used_chunks),
+                        'diagram': stream_result.get('diagram'),
                     }
                     if cacheable:
                         answer_cache.set(cache_key, {
@@ -591,6 +596,7 @@ class AskAIView(APIView):
                     'messageId': str(existing.assistant_message_id),
                     'suggestedFollowUps': existing.suggested_follow_ups,
                     'remainingQuota': max(DAILY_AI_QUOTA - used_today, 0),
+                    'diagram': existing.assistant_message.diagram,
                     'usedChunks': [],
                 })
                 return
@@ -601,6 +607,7 @@ class AskAIView(APIView):
                 'messageId': str(assistant_message.id),
                 'suggestedFollowUps': follow_ups,
                 'remainingQuota': max(DAILY_AI_QUOTA - used_today, 0),
+                'diagram': assistant_message.diagram,
                 'usedChunks': [
                     {'title': c.get('title', ''), 'summary': c.get('summary', '')}
                     for c in used_chunks
@@ -663,6 +670,7 @@ class AskAIView(APIView):
             'answer': existing.assistant_message.text,
             'suggestedFollowUps': existing.suggested_follow_ups,
             'remainingQuota': remaining_quota,
+            'diagram': existing.assistant_message.diagram,
         }
         return AskResponseSerializer(data)
 
@@ -683,7 +691,8 @@ class ConversationMessagesView(APIView):
             'conversationId': str(conversation.id),
             'lessonId': str(conversation.lesson_id) if conversation.lesson_id else None,
             'messages': [
-                {'messageId': str(m.id), 'role': m.role, 'text': m.text} for m in messages
+                {'messageId': str(m.id), 'role': m.role, 'text': m.text, 'diagram': m.diagram}
+                for m in messages
             ],
         }
         return Response(ConversationMessagesResponseSerializer(data).data)