File editing problems

Sometimes the LLM will reply with some code changes that don't get applied to your local files. In these cases, aider might say something like "Failed to apply edit to filename" or other error messages.

This usually happens because the LLM is disobeying the system prompts and trying to make edits in a format that aider doesn't expect. Aider makes every effort to get the LLM to conform, and works hard to deal with LLM edits that are "almost" correctly formatted.

But sometimes the LLM just won't cooperate. In these cases, here are some things you might try.

Use a capable model

If possible try using GPT-4o, Claude 3.5 Sonnet or Claude 3 Opus, as they are the strongest and most capable models.

Weaker models are more prone to disobeying the system prompt instructions. Most local models are just barely capable of working with aider, so editing errors are probably unavoidable.

Local models which have been quantized are even more likely to have problems because they are not capable enough to follow aider's system prompts.

Try the whole format

Run aider with --edit-format whole if the model is using a different edit format. You can see which edit format it is using in the announce lines:

Aider v0.50.2-dev
Models: claude-3-5-sonnet-20240620 with ♾️ diff edit format

Reduce distractions

Many LLMs now have very large context windows, but filling them with irrelevant code or conversation can confuse the model.

• Don't add too many files to the chat, just add the files you think need to be edited. Aider also sends the LLM a map of your entire git repo, so other relevant code will be included automatically.

• Use /drop to remove files from the chat session which aren't needed for the task at hand. This will reduce distractions and may help the LLM produce properly formatted edits.

• Use /clear to remove the conversation history, again to help the LLM focus.

• Use /tokens to see how many tokens you are using for each message.

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