How to configure to review individual commits?

[Hi-Angel]

Hi, I'm looking for a project to conduct codereview via AI on Gitlab MRs. Figured somebody might have created a code for this, so I found this project.

But, having looked through review documentation, there's a thing I am confused by: the project seem to lack ability to review commits, as opposed to whole PR/MR diff. A whole diff sometimes is interesting, sure, but codereviewing that would be strange. You want to be sure every commit has separate logical change with description matching the functionality… Also, commit descriptions always contain important for proper review information — you can't give good quality review to a diff with a bunch of stuff changed, where it's unclear what and why was moved.

So, it's odd to see in documentation quotes like:

When a PR diff is larger than the model's token budget […]

…and nothing about separate commit diff.

Am I missing something here, is perhaps per-commit codereview just not documented?

[abhiramshaji-cyber]

You are not missing anything: /review has no per commit mode. It always reviews a diff of the MR, either the whole thing or, with -i, the commits added since the last review. There is no option that walks the commits one by one and reviews each diff against its own message.

What exists today:

1. Incremental review: /review -i

-i is parsed in PRReviewer.parse_incremental. On GitLab, get_incremental_commits finds the previous review note and limits the diff to commits pushed after it (gitlab_provider.py#L820-L860). If no earlier review exists, it falls back to a full review. Tuning knobs are under [pr_reviewer] (minimal_commits_for_incremental_review, minimal_minutes_for_incremental_review, require_all_thresholds_for_incremental_review, configuration.toml#L207-L210).

So if you push one logical commit at a time and run /review -i after each push, you effectively get a review per commit. It does not help for an MR that arrives with ten commits at once.

2. Commit messages are mostly not in the review prompt

The reviewer fetches get_commit_messages() (pr_reviewer.py#L267), but the template only renders them when require_estimate_contribution_time_cost is on (pr_reviewer_prompts.toml#L311-L317). If you want the model to compare messages against the code, you can enable that flag and add extra_instructions, accepting that you also get the time estimate section:

[pr_reviewer]
require_estimate_contribution_time_cost = true
extra_instructions = """
Check that each commit is one logical change and that its message matches the code it touches.
"""

That still reviews the combined diff, though, so the model cannot reliably tell which hunk came from which commit.

3. Real per commit review

That would need a new mode (iterate the MR commits, fetch each commit's diff, review it with its message). Worth opening a feature request issue for, since none of the providers implement it now.

[Hi-Angel]

Wow, okay. I guess I'll create a feature request then…

[abhiramshaji-cyber]

Ha, fair, sorry it's not the answer you were hoping for! One thing that gets pretty close today: if you push one commit at a time and run /review -i after each push, each review only looks at what's new since the last one, so you end up with roughly a review per commit.

A feature request sounds like a great idea though. If you open one, feel free to link this discussion, and it might help to mention that the incremental review already tracks commits since the last review, so per commit reviews could build on that. Happy to add a 👍 there if you drop the link here.

[Hi-Angel]

Thanks!

One thing that gets pretty close today: if you push one commit at a time and run /review -i after each push, each review only looks at what's new since the last one, so you end up with roughly a review per commit.

Oh, well… Okay, but usually people force-push multiple commits (where they fixed something found by codereview), what will happen the, will PR-Agent review those commits individually?

A feature request sounds like a great idea though. If you open one, feel free to link this discussion

Sure, created here, and it also has a link to this discussion 😊

[abhiramshaji-cyber]

Thanks for opening #4470, I added a 👍 to it.

To answer your question: no, they get reviewed together. I went through the GitLab code to be sure. /review -i finds the last review note on the MR, then walks the MR's commits from newest to oldest and treats every commit whose committer date is later than that note as new. It then diffs the last commit from before the note against the current head and reviews that as one combined diff, so three new commits give you one review, not three.

Force pushing matters here because it goes by commit dates, not by remembering which SHAs it already saw. A rebase or amend gives the rewritten commits a fresh committer date, so everything from the first commit you touched onward counts as new again, even commits whose content didn't change. If the rewrite reaches back to the very first commit on the branch, there's nothing older to anchor on and it falls back to a full review.

So for the fixup workflow you describe, -i won't get you a review per commit. That's exactly the gap your feature request covers, and I think it's a good one.