`gh stack push` resolves an empty remote and silently pushes nothing when `branch.<name>.remote` is `.`

Start at the remote auto-detection and push paths used by gh stack push, then compare their handling of branch.<name>.remote = . with the single-remote and remote.pushDefault cases. Reproduce the issue using the commands and repository described above, and verify that unresolved remotes fail loudly, actual ref movement is reported, and the exit status is non-zero when nothing was pushed.

Summary

When a stack branch's branch.<name>.remote is . (the local repository), gh stack push resolves the push remote to an empty string, pushes nothing, and reports success:

$ gh stack push
Pushing 2 branches to ....
✓ Pushed 2 branches
To create PRs for this stack, run `gh stack submit`

$ git ls-remote --heads origin | grep probe
                       # nothing — no ref was created

Note the blank remote name between "to" and the ellipsis. Exit status is 0.

gh stack submit then fails PR creation, but the error describes a state problem rather than the push failure that caused it, and the run still ends on a success line:

$ gh stack submit --auto
Checking stack state...
Pushing to ....
⚠ failed to create PR for probe-one: creating PR: GraphQL: Head sha can't be blank,
  Base sha can't be blank, No commits between main and probe-one,
  Head ref must be a branch (createPullRequest)
✓ Pushed and synced 2 branches

This is a single-remote repository. origin is the only remote, and it is correct.

Root cause

branch.<name>.remote = . is a normal git configuration meaning "the upstream is a local branch". Anyone with branch.autoSetupMerge = always in their git config gets it automatically on every git switch -c from a local branch — which is exactly how a stack is built, so every branch in the stack has it.

Remote auto-detection appears to read branch.<name>.remote, find ., and yield an empty remote name rather than falling back to the single remote / origin.

Isolated by toggling it:

branch.autoSetupMerge	branch.<name>.remote	gh stack push	branches pushed
always	.	Pushing 2 branches to ....	0
unset	unset	Pushing 2 branches to origin...	2

Also fixed by setting remote.pushDefault = origin; unsetting it reproduces the failure again, deterministically.

Reproduction

git config --global branch.autoSetupMerge always   # or set it locally

git switch main
git switch -c probe-one && echo p1 > p1.txt && git add . && git commit -m "p1"
git switch -c probe-two && echo p2 > p2.txt && git add . && git commit -m "p2"
git switch probe-one

git config --get branch.probe-one.remote           # -> .
gh stack init probe-one probe-two
gh stack push                                      # "Pushing 2 branches to ...." / "✓ Pushed 2 branches"
git ls-remote --heads origin | grep probe          # -> nothing

Public repo with two stacks set up for this: https://github.com/xn/gh-stack-repro

Expected

• Fail loudly when the push remote cannot be resolved, rather than pushing to an empty remote name.
• Never print ✓ Pushed N branches unless refs actually moved — report per-branch results, and exit non-zero when nothing was pushed.
• Treat branch.<name>.remote = . as "no usable remote for this branch" and fall back to the single remote / origin / remote.pushDefault.

Workaround

gh stack push --remote origin, or git config remote.pushDefault origin.

Environment

• gh 2.97.0
• gh-stack v0.1.0
• git 2.50.1
• macOS 26.4.1, darwin/arm64

Related

Same GraphQL error signature as #219 and #381, but a different root cause — those are about which repository the API calls target in multi-remote/fork clones. This one is a single-remote clone where the push target itself resolves to empty and no ref is ever created. #45 is a third variant (SSH host alias); ruled out here — the failure reproduces with a plain https:// remote and a pristine global config.