[FF] `prevent_approval_removal_during_merge` -- Block approval removal while a merge is in flight

Summary

Roll out the feature currently behind the prevent_approval_removal_during_merge feature flag.

DRI: @marc_shaw
Team Slack channel: #g_code_review

Note

Process and guidance live in the docs — this issue is just the commands and a place to track the rollout. "Rolling out" means incrementally enabling the flag on GitLab.com to validate stability — it is not the same as releasing the feature, which happens when the flag is removed. Feature flag controls · Feature flag lifecycle

What could go wrong?

Blast radius is projects that require approvals. When the flag is enabled:

MergeRequests::RemoveApprovalService refuses to remove an approval while the MR is locked? (the git-merge window), surfaced as a 404 by the unapprove API.
EE::MergeRequests::MergeService re-reads approval (fresh cache) inside the merge lock and aborts the merge if the MR is no longer approved.

Main risk: a false-negative approval re-check aborting a legitimate merge at the git-write boundary (the in-lock approved? disagreeing with the earlier validate! mergeability check). Watch merge-service error rates and Merge request is not approved merge errors on https://dashboards.gitlab.net. Rollback is instant via the flag — flag off restores the prior behaviour, including the previous approval-deletion logging.

Rollout

Run all production /chatops in #production and cross-post the results to #g_code_review. Background: incremental rollout process, feature actors.

Non-production

/chatops gitlab run feature set prevent_approval_removal_during_merge 50 --actors --dev --pre --staging --staging-ref
/chatops gitlab run feature set prevent_approval_removal_during_merge true --dev --pre --staging --staging-ref

Production — percentage rollout (wait ≥15 min between steps, watch dashboards):

/chatops gitlab run feature set prevent_approval_removal_during_merge <percentage> --actors

Or target specific actors instead:

/chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss prevent_approval_removal_during_merge true
/chatops gitlab run feature set --group=gitlab-org,gitlab-com prevent_approval_removal_during_merge true
/chatops gitlab run feature set --user=marc_shaw prevent_approval_removal_during_merge true

Before global rollout

Confirm the relevant gotchas before going to 100% — see enabling a feature for GitLab.com:

Docs + version history updated
Breaking changes announced, if any
Change management issue opened, if required
External API consumers handled with a fail-open mechanism, if applicable

Cleanup

Remove the flag once deemed stable — see cleaning up. Track it here, or open a follow-up Feature Flag Cleanup issue. Remove the flag and its YAML definition from the codebase, then:

/chatops gitlab run release check https://gitlab.com/gitlab-org/gitlab/-/merge_requests/243660 19.2
/chatops gitlab run feature delete prevent_approval_removal_during_merge --dev --pre --staging --staging-ref --production

Rollback

/chatops gitlab run feature set prevent_approval_removal_during_merge false                                         # production
/chatops gitlab run feature set prevent_approval_removal_during_merge false --dev --pre --staging --staging-ref     # non-production
/chatops gitlab run feature delete prevent_approval_removal_during_merge --dev --pre --staging --staging-ref --production  # remove entirely

[FF] prevent_approval_removal_during_merge -- Block approval removal while a merge is in flight