Fzf reverse history search

[bart2]

This PR implements #3575

I find fzf a very convenient way to search shell history and was missing that functionality in aider.

Demo showcasing fzf based reverse history search in aider with ctrl-r:

Screen.Recording.2025-07-19.at.1.45.31.PM.mov

[CLAassistant]

All committers have signed the CLA.

[veracioux]

Hi @bart2. Does this also add a configuration option in the config files? Sorry if it's a stupid question, I'm still in the early stages of getting familiar with the codebase.

[bart2]

Hi @bart2. Does this also add a configuration option in the config files? Sorry if it's a stupid question, I'm still in the early stages of getting familiar with the codebase.

Yeah, the test above was done with the following in the .aider.conf.yml config file:

fzf-history-search: true

I didn't pass the command line option.

[meliache]

Is there anything to this fzf-specific except the subprocess command? I think it would be a more general interface to have a history_command option. Then, in the configuration, the user could specify:

history_search_command: ["fzf", "--reverse", "--height", "20"]

Advantages

• the user can customize the fzf cli options, e.g. choose a different height, without any need for additional configuration options
• the user could easily use a different fuzzy finder, e.g. skim
• if no history search command is provided, the revert to the default behaviour.
• according to "A Philosophy of Software Design" by John Ousterhout, interfaces should be as general and simple as possible. A config is also an interface.

Disadvantages

• Enabling fzf history search is quite complex this way. If you e.g. want to enable it on the command line via --history-search-command, you would need to provide all fzf cli options correctly, not sure how practical it is
• If you use a different fuzzy searcher, it might not work if the output is formatted differently than the fzf-output
• The above two options mean that such an option should be documented well, maybe with the fzf-command provided as an example.

Alternative: Keep the current code, but make the cli option --history-search fzf

I think it's fine only adding fzf support for now with the code as it currently is in the PR, but in the future somebody might want to add support for a different fuzzy finder. So instead of having a fzf_history_search boolean option, I think it would be better having a history_search: Literal["default", "fzf"] option and add the choices to the cli via click.option("history_search", choices=["default", "fzf"], ...), so that the user can do --history-search fzf. Just implementing this would require very little changes to this PR. But then, if e.g. skim-support is added in the future, there would be no need in introducing a new cli flag (and to think what happens if both fzf and skim are flags are true), but just an additional option.

DISCLAIMER: I'm not an aider developer/maintainer, so don't take this comment as blocking. I'm just a programmer and aider user, as well as a fan of fuzzy search and good cli's. So when I saw this PR I decided to take a look. Having fuzzy history search would be awesome!

[vk4s]

If anyone's interested. I have added history search feature in #4344.