You can fix this using a system prompt to force it to reply just with a diff. It makes the generation much faster and much less prone to changing unrelated lines. Also try reducing the temperature to 0.4 for example, I find the default temperature of 1 too high. For sample system prompts see Aider Chat: https://github.com/Aider-AI/aider/blob/main/aider/coders/edi...