Fix Gemma chat template system prompt compatibility in apple_llm.py

apple_llm.py

@@ -195,12 +195,27 @@ class MacOSLLM(FrameProcessor):
                 def _gen():
                     from mlx_lm import generate
                     from mlx_lm.sample_utils import make_sampler
+
                     # Keep history concise to avoid context drift and repetition
-                    recent_history = self._history[-8:]
-                    messages = [{"role": "system", "content": self._system_prompt}] + recent_history
-                    prompt = self._mlx_tokenizer.apply_chat_template(
-                        messages, add_generation_prompt=True, tokenize=False
-                    )
+                    recent_history = [dict(m) for m in self._history[-8:]]
+                    if recent_history:
+                        if self._system_prompt:
+                            recent_history[0] = {
+                                "role": recent_history[0]["role"],
+                                "content": f"{self._system_prompt}\n\n{recent_history[0]['content']}"
+                            }
+                        messages = recent_history
+                    else:
+                        messages = [{"role": "user", "content": f"{self._system_prompt}\n\n{utterance}"}]
+
+                    try:
+                        prompt = self._mlx_tokenizer.apply_chat_template(
+                            messages, add_generation_prompt=True, tokenize=False
+                        )
+                    except Exception:
+                        # Fallback for models without chat template support
+                        prompt = f"{self._system_prompt}\n\nUser: {utterance}\nAssistant:"
+
                     sampler = make_sampler(temp=0.7)
                     return generate(
                         self._mlx_model,