Connect or update a project's repo connection

The caller's user_git_connections row (see /user/git/connections).

Stable GitHub repository id (repository.id), the preferred selector. Either repository_id or repo_full_name is required; when both are given they must identify the same live repository.

Deprecated selector kept for a compatibility window; prefer repository_id. Either repository_id or repo_full_name is required.

Monorepo subdirectory the project builds from. Omit for the repo root.

The branch a push must land on to deploy, with three cases, because this is a full replace and a read-modify-write client sends back whatever it read. Omit it to follow the repository's GitHub default branch, which also discards a branch set earlier. Send back the branch the project already deploys from, when that is the repository's default, and nothing changes either way — a project pinned to that branch stays pinned. Sending the default branch when the project deploys from something else returns it to following the default, including on a rebind, where a pin describes a branch chosen for the repository being left. Any other branch becomes the project's own choice, exempt from later default-branch renames. Validated as a Git branch name only: it does not have to exist yet, so a project can be pointed at a branch about to be pushed. Changing repository and naming a branch other than the new repository's default in one request is refused with 400, because the branch named is almost always the previous repository's, echoed back — connect first, then set the branch.

Stable GitHub repository id (repository.id), the authoritative binding.

The branch a push must land on to deploy. Follows the repository's GitHub default branch unless the project set its own, which a default-branch rename on GitHub then leaves alone.