Skip to content

gh stack rebase uses the wrong onto boundary for merged branches #512

Description

@cmolder

Problem: gh-stack needs to know "what was branch X's last commit right before it got merged" so it can skip replaying that history into upstack branches. Currently, it resolves this from the local clone instead of GitHub.

So, if branch X gets rebased elsewhere before merging, the local copy goes stale. That's normal and expected, however gh stack rebase fails to notice this and tries to replay from the wrong commit. This has led to spurious merge conflicts on files I didn't even touch, leading me to rebasing branches one-by-one or fixing the gh-stack state by hand (or with an agent).

Fix: I wrote a fix here. Full disclosure: I used Claude to write the fix but I manually reviewed and edited it afterwards.

I would open a PR for this but it's locked to contributors only.

Changes:

  1. internal/github/github.go: Add one field, HeadRefOid, to PullRequest. This tracks the remote's record of the exact commit which was merged.
  2. cmd/utils.go:
    • When a PR is detected as merged, save its HeadRefOid value.
    • When computing the rebase boundary, use HeadRefOid instead of getting the (possibly stale) local SHA through git.
  3. cmd/rebase_test.go: Add a test that fakes the problem scenario ("local has SHA A, but remote has SHA B (the real merge point)" and checks the tool picks B. This test fails without the above fixes, and passes with them.

Net effect: The onto boundary now comes from remote / GitHub (can't go stale) instead of local, eliminating confusing rebase conflicts due to a misconfigured rebase.

Activity

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions