Merge Queue and branch up to date protection

[tiagolobocastro]

Hi folks,

I've enabled batch_size to allow multiple PRs merging at once but this came with an error:

The branch protection setting Require branches to be up to date before merging is not compatible with batch_size>1 and must be unset.

Then I set queue_branch_merge_method: fast-forward allowing the draft PR to merge and this does work now with the Require branches to be up to date before merging enabled.
This is the config I'm testing with:

queue_rules:
  - name: default
    update_method: rebase
    merge_method: merge
    allow_inplace_checks: true
    batch_size: 10
    queue_branch_merge_method: fast-forward

merge_queue:
  max_parallel_checks: 1

The downside is that it seems that even though allow_inplace_checks: true is enabled, now it always creates the draft PR? Is this expected?
Also is it possible to use mergify and the github merge queue together btw? Ex: rather than queue on a draft PR for example, send to the github merge queue?

[jd]

The downside is that it seems that even though allow_inplace_checks: true is enabled, now it always creates the draft PR? Is this expected?

Yes, this is expected. allow_inplace_checks will disappear soon anyhow.

Also is it possible to use mergify and the github merge queue together btw? Ex: rather than queue on a draft PR for example, send to the github merge queue?

Possibly. I don't think anyone ever tried that — if you're leveraging Mergify MQ, I'm not sure of the benefit of using the GH MQ compared to the complexity it'd add.

[tiagolobocastro]

Yes, this is expected. allow_inplace_checks will disappear soon anyhow.

What's the reason behind it if I may ask?
The biggest advantage I see with it is if there's no changes on the base and the tests already passed, then we don't need to test again or is that still holding true with allow_inplace_checks disabled?

Also, if I disable Require branches to be up to date is there anything I could do to guard against mistakenly merging a PR from the github UI? That's what is kind of making me less willing to use batch_size with queue at the moment.

[jd]

What's the reason behind it if I may ask?

We plan to remove allow_inplace_checks to simplify the configuration and make Mergify's behavior more predictable and consistent across all setups.

Having different logic depending on whether this option is enabled creates complexity and confusion — especially when debugging or onboarding new teams. By consistently using the same approach (a temporary branch and PR to test the merge), we ensure reliable, reproducible CI runs and make the system easier to maintain and understand for everyone.

The biggest advantage I see with it is if there's no changes on the base and the tests already passed, then we don't need to test again or is that still holding true with allow_inplace_checks disabled?

This is an optimization that will stay.

Also, if I disable Require branches to be up to date is there anything I could do to guard against mistakenly merging a PR from the github UI? That's what is kind of making me less willing to use batch_size with queue at the moment.

You should block any merge outside Mergify.