Fix duplicate: remove event.data fallback, only use contentBlockDelta.delta.text

src/lambdas/agent-runner/handler.py

@@ -236,11 +236,13 @@ def handler(event, context):
                         continue
                     if not isinstance(event, dict):
                         continue
-                    # Extract text delta from contentBlockDelta
+                    # Extract text delta from contentBlockDelta ONLY
+                    # Do NOT use event.get('data') — that's the full formatted summary,
+                    # causing duplicate delivery alongside the token stream.
                     delta = event.get('event', {}).get('contentBlockDelta', {}).get('delta', {})
                     if not isinstance(delta, dict):
                         continue
-                    token = delta.get('text', '') or event.get('data', '')
+                    token = delta.get('text', '')
                     if token:
                         text_buffer += token
                         flush = (