fix(llm): transform message content for Groq provider

Ensure message content is a string for Groq API compatibility.
Groq doesn't support the array format used by other providers.

Co-authored-by: Bob <[email protected]>

gptme/llm/llm_openai.py

@@ -117,6 +117,7 @@ def chat(messages: list[Message], model: str, tools: list[ToolSpec] | None) -> s
         messages = list(_prep_o1(messages))
 
     messages_dicts = handle_files(msgs2dicts(messages))
+    _transform_msgs_for_special_provider(messages_dicts)
 
     from openai import NOT_GIVEN  # fmt: skip
 
@@ -148,6 +149,7 @@ def stream(
         messages = list(_prep_o1(messages))
 
     messages_dicts = handle_files(msgs2dicts(messages))
+    _transform_msgs_for_special_provider(messages_dicts)
 
     from openai import NOT_GIVEN  # fmt: skip
 
@@ -278,6 +280,14 @@ def _process_file(msg: dict) -> dict:
     return msg
 
 
+def _transform_msgs_for_special_provider(messages_dicts: list[dict]):
+    if get_provider() == "groq":
+        # groq needs message.content to be a string
+        messages_dicts = [
+            {**msg, "content": msg["content"][0]["text"]} for msg in messages_dicts
+        ]
+
+
 def parameters2dict(parameters: list[Parameter]) -> dict[str, object]:
     required = []
     properties = {}