Extract text from Gradio 6 content blocks: model was receiving empty user turns

app.py

@@ -703,7 +703,16 @@ def _history_for_model(history: list) -> list[dict]:
             continue
         content = msg.get("content", "")
         if isinstance(content, list):
-            content = ""
+            # Gradio 6 sends message content as a list of blocks.
+            parts = []
+            for block in content:
+                if isinstance(block, str):
+                    parts.append(block)
+                elif isinstance(block, dict):
+                    text = block.get("text") or block.get("content") or ""
+                    if isinstance(text, str) and text:
+                        parts.append(text)
+            content = "\n".join(parts)
         if role == "assistant":
             content = _strip_thinking(content)
         if content: