Fix Gradio inference function in chat app

Gradio v5 changed required function signature for inference function from tuples of (human, ai) message to flat list of messages. This was not caught by the automated testing because AFAICT the Gradio python client doesn't provide a way to send multiple messages to create a conversation.

Author: sd109

web-apps/chat/app.py

@@ -66,19 +66,27 @@ def inference(latest_message, history):
     global BACKEND_INITIALISED
 
     try:
+        context = []
         if INCLUDE_SYSTEM_PROMPT:
-            context = [SystemMessage(content=settings.model_instruction)]
+            context.append(SystemMessage(content=settings.model_instruction))
         else:
-            context = []
-        for i, (human, ai) in enumerate(history):
-            if not INCLUDE_SYSTEM_PROMPT and i == 0:
-                # Mimic system prompt by prepending it to first human message
-                human = f"{settings.model_instruction}\n\n{human}"
-            context.append(HumanMessage(content=human))
-            context.append(AIMessage(content=(ai or "")))
+            # Mimic system prompt by prepending it to first human message
+            history[0]['content'] = f"{settings.model_instruction}\n\n{history[0]['content']}"
+
+        for message in history:
+            role = message['role']
+            content = message['content']
+            if role == "user":
+                context.append(HumanMessage(content=content))
+            else:
+                if role != "assistant":
+                    log.warn(f"Message role {role} converted to 'assistant'")
+                    context.append(AIMessage(content=(content or "")))
         context.append(HumanMessage(content=latest_message))
+
         log.debug("Chat context: %s", context)
 
+
         response = ""
         for chunk in llm.stream(context):
             # If this is our first successful response from the backend
@@ -109,6 +117,7 @@ def inference(latest_message, history):
             raise gr.Error(ui_message)
 
     except openai.APIConnectionError as err:
+        log.info(err)
         if not BACKEND_INITIALISED:
             log.info("Backend API not yet ready")
             gr.Info(