Persists the chosen repository + branch onto the app’s existing git_connection. The next push to branch triggers the deploy webhook which materializes templates and datasets.
Requires an existing OAuth install (returns 409 git_connection_missing otherwise). A repo+branch pair can be watched by only one app per organization — linking a pair already linked to another app returns 409 repo_branch_already_linked. Idempotent — re-linking the same repo+branch is a no-op aside from a commit_sha refresh.
Application ID for tenant scoping
API key (sk_agentmark_*)
Repository linked.