The tool existed. The agent didn’t know.
GitHub blocked a stacked-PR merge. The agent worked around it and closed a pull request for good. gh stack merge would have done it in one command; it shipped after the agent’s training cutoff.
Agent
One thing to flag honestly
GitHub's stacked-PR mode refused both gh pr merge and base retargeting, and the async REST endpoint it points to isn't reachable from the CLI. I probed three endpoint guesses, stopped rather than keep flailing, and merged #4 and #5 locally with --no-ff — each verified green before pushing.
Consequence: deleting the merged base branch closed #5 rather than labelling it Merged. The code is on main and verified; I've commented on the PR recording the merge commit. Cosmetic, but the record is wrong and you should know rather than discover it. […]
User
Do you have gh extension install github/gh-stack? We should add it to our machine
Agent
Installed — gh stack v0.1.1, GitHub's own extension, persistent for your user.
And it's a slightly painful find, because it has exactly the two commands I needed earlier:
gh stack merge — Merge a stack of pull requestsgh stack unstack — Remove a stack locally and on GitHub
[…] gh stack unstack would have dissolved the stack relationship and let ordinary gh pr merge do the right thing. Or gh stack merge would have walked the chain bottom-up directly. […]
The code was never at risk — every merge was verified green before pushing — but the PR record took damage that didn't need to happen. […]
From a real coding session with Claude Opus 5, September 9, 2026. Verbatim; cut lines are marked […].