Claude Code System Prompts

The branch a commit landed on (from the commit summary line git prints per commit) or a push updated (from the ref-update line git prints per pushed ref, e.g. HEAD -> other). Commit and push events carry it; a command that pushed several branches emits one push event per branch. A best-effort hint: absent whenever attribution is uncertain (a push whose output was redirected still emits, with no branch; a push that also updated a ref whose name could not be carried emits a nameless event beside the named ones), and never a required key.