gptel-context: Allow exclusion of gitignored files

[benthamite]

Continuing the discussion here, this PR allows the user to exclude, by setting the user option gptel-context-exclude-gitignored to t, gitignored files or directories from the context.

Tagging participants in previous discussion: @hartikainen, @collinarnett, @metachip, @sandinmyjoints.

[benthamite]

(I just noticed that I forgot to set the default value of gptel-context-exclude-gitignored to nil, but now I wonder if we should leave it as t. I don’t have a clear view on this.)

[collinarnett]

I would set it to t by default. I tested out the new add directory functionality on a repository with node_modules folder and it froze my emacs adding thousands of files to the context window. Other utilities like RepoMix enable gitignore exclusion by default as well.

[karthink]

Looks good. I've got one performance concern and one behavior suggestion.

[karthink]

Could you move all the git-related functions gptel-context--git-files, gptel-context--skip-file-p, gptel-context--message-git-skipped and gptel-context--build-git-cache into one place in the file? You can add a ;;; git tracking functions header over them for navigation.

Additionally, anywhere you run a file-name function like file-relative-name on a file, please check that the file argument can't be nil. I haven't analyzed all possible cases.

[karthink]

locate-dominating-file can be very slow on remote files, to the point of locking up Emacs for a while.

It might be worth using file-remote-p and skipping the gitignore check if it's a remote file.

[benthamite]

@karthink, I believe I have now addressed all your requested changes. Let me know if you have further comments.

[vermiculus]

Late to the party here (and I wouldn't want to derail this feature; I was recently bitten by it), but was the use of project.el (via project-files) considered now that it's included in emacs? That would get you cross-VCS support for free.

[benthamite]

Hi @vermiculus. I didn’t consider using project.el because I am not familiar with that package. Let me take a look and I’ll see if I can adapt it.

[benthamite]

@vermiculus: I revised the PR to make it use project.el. The code is simpler now.

It would be great if folks could test this before it is merged: I’m not a programmer and my eyes may fail to catch problems.

[vermiculus]

Took a pass here, though I'm just on my phone so sorry for formatting.

How does this perform functionally for you? Any noticeable delay with larger/smaller projects with more/fewer ignored build artifacts?

[pabl0]

I see some whitespace changes that apparently just change spaces to TABs, most likely since emacs has indent-tabs-mode on by default, and especially if you have aggressive-indent-mode on, it can cause unecessary changes in places you did not even meant to touch. (This is why I submitted #712.) In case you remove those changes, consider doing some squashing as well, this PR has currently 34 commits and I think some of them could be squashed together to make the git history cleaner.

[benthamite]

I think I'm basically done with the changes here. My only concern is that (member file gptel-context--project-files) may be a bit slow for projects with lots of files. I believe this issue arose after we started using project.el, and happens because (member file gptel-context--project-files) has to linearly search through the entire list of project files to check if a file is present. Claude suggests using a hash table, but I don’t know enough Elisp to implement this suggestion.

If and when @karthink agrees to merge this PR, I'm happy to do some squashing to clean up the commit history.

[benthamite]

(If the performance issue is not addressed, I am now inclined to set the default value of gptel-context-restrict-to-project-files to nil.)