Support evilmartian's lefthook

[professor]

NOTE TO SELF: when doing git commit -v do not be committing the .lefthook.yml file as its state may be changing while doing development of this issue.

I see this as a feature request, but I feel like I'm writing it up as a bug. Opps!?!?!

Is your feature request related to a problem? Please describe.
https://github.com/evilmartians/lefthook is a tool for managing git hooks. My employer uses it to run several different programs that look at each commit for various reasons.

When lefthook runs, if it detects a file in .git/hooks that it needs to override, it will back up the file.

1934 Jun 13 14:59 pre-commit
      2 Jun 13 06:56 pre-commit.old -> /opt/homebrew/bin/mit-pre-commit

In this case, the pre-commit is lefthook bash that will run everything defined in a lefthook.yml file

Of the three git hooks that git-mit uses, our lefthook only uses pre-commit

Describe the solution you'd like
I'm currently experimenting with this solution

.lefthook-local.yml

pre-commit:
  commands:
    git-mit:
      run: /opt/homebrew/bin/mit-pre-commit

If authorship hasn't been set, this will correctly print out this error. Awesome!

Error: mit_pre_commit::errors::stale_author_error

  × The details of the author of this commit are stale
   ╭────
 1 │ 2025-06-13 13:52:01.0 -07:00:00
   · ───────────────┬───────────────
   ·                ╰── The previously set authors expired at this time
   ╰────
  help: Can you confirm who's currently coding? It's nice to get and give
        the right credit. You can fix this by running `git mit` then the
        initials of whoever is coding for example: `git mit bt` or `git mit
        bt se`

However, the commit message itself will not have the co-authored field.

ls -al .git/hooks

commit-msg -> /opt/homebrew/bin/mit-commit-msg

Solution 1
The following works...

cd workspace/repo
ln -s /opt/homebrew/bin/mit-prepare-commit-msg .git/hooks/prepare-commit-msg
ln -s /opt/homebrew/bin/mit-commit-msg .git/hooks/commit-msg

.lefthook-local.yml

pre-commit:
  commands:
    git-mit:
      run: /opt/homebrew/bin/mit-pre-commit

The commit message will have authorship.

(Possible) Solution 2
I felt like this would be a more robust solution...

.lefthook-local.yml

pre-commit:
  commands:
    git-mit:
      run: /opt/homebrew/bin/mit-pre-commit

commit-msg:
    commands:
      git-mit:
        run: /opt/homebrew/bin/mit-commit-msg

prepare-commit-msg:
  commands:
    git-mit:
      run: /opt/homebrew/bin/mit-prepare-commit-msg

but it results in this error:

error: the following required arguments were not provided:
  <COMMIT_MESSAGE_PATH>

ls -al .git/hooks | grep mit

1934 Jun 13 15:12 commit-msg
  32 Jun 13 06:56 commit-msg.old -> /opt/homebrew/bin/mit-commit-msg
1934 Jun 13 15:12 pre-commit
  32 Jun 13 06:56 pre-commit.old -> /opt/homebrew/bin/mit-pre-commit
1942 Jun 13 15:12 prepare-commit-msg
  40 Jun 13 15:09 prepare-commit-msg.old -> /opt/homebrew/bin/mit-prepare-commit-msg

[professor]

I was able to get Solution 2 working on a new machine.....

brew install PurpleBooth/repo/git-mit
cd ~/workspaces/<REPO>
git mit-install
git init
cp lefthook-local.yml.example .lefthook-local.yml
cat >> .lefthook-local.yml << EOF
pre-commit:
  commands:
    git-mit:
      run: /opt/homebrew/bin/mit-pre-commit
commit-msg:
  commands:
    git-mit:
      run: /opt/homebrew/bin/mit-commit-msg
prepare-commit-msg:
  commands:
    git-mit:
      run: /opt/homebrew/bin/mit-prepare-commit-msg

UPDATE: This wasn't reproducable.

 git mit ts aw
  ⚠ Hooks not found in this repository, your commits won't contain trailers, and lints will not be checked
  help: `git mit-install` will fix this

This fortunately still sets the author

git commit -v
summary: (done in 16.45 seconds)
✔️ git-mit
✔️ packwerk_validate
✔️ packwerk_check_unused_dependencies
✔️ codeowners

summary: (done in 0.00 seconds)
🥊 git-mit

[PurpleBooth]

I'll have a crack at adding a test with one of the popular hook frameworks I guess, I feel like it playing nice with one of those is probably a thing most people expect

[professor]

Thanks. I feel like I'm missing something obvious.

I'll be trying solutions and they will start "working" and then stop working when I try to reproduce them on another repo on my machine. Part of the issue is that it is not clear to me when I need to run git init

[PurpleBooth]

The git init command is only needed in specific circumstances with git-mit:

When you need to run git init:

• You've installed git-mit globally using git mit-install --scope=global
• You want to add git-mit hooks to a repository that existed before the global installation

How global installation works:
When you run git mit-install --scope=global, it:

1. Sets the global init.templatedir configuration (viewable with git config --global init.templatedir)
2. Points to a directory containing symlinks to git-mit hook binaries
3. These template files are automatically copied to .git/hooks/ when git init runs

For existing repositories:
Since existing repos won't have the hooks (they were created before global installation), you need to run git init to copy the template hooks into the existing .git directory.

Note: The current warning message may be triggering inappropriately and needs adjustment. It checks (iirc) that the hook binary is symlinked at the .git/hooks/whatever directory when you run git-mit, which if you're using a hook manager, won't be true

[PurpleBooth]

Dear Future Billie (or random person who fancies submitting a drive-by PR),

• Add a test that validates these can be used with popular hook managers
• Document how to use this with a hook manager
• Ensure the warning only triggers if there are no hooks at all in the repository setup (so the warning doesn't show for hook manager users)