The Commit That Talks Before You Push
One safety net at the hackathon didn't need the model to cooperate. The other did.
You commit. Before you even type push, a message is already sitting in the shared room: your branch, your commit, the files you touched. Nobody wrote it. A git hook did.
We built this at a Codex hackathon, for the moment every fast-moving team hits: two people editing the same file without knowing, finding out at a merge conflict instead of before one. The goal was a room that knows what teammates are doing before GitHub does.
Two mechanisms carry that, and they don't trust the same thing.
The first is a post-commit hook. git config core.hooksPath .githooks points every commit and push at a script that reads the branch, the commit, the changed files, and posts a note to the room. No prompting, no model involved. It fires whether or not Codex is paying attention, because git always runs the hook.
The second is softer. Codex is told, in a tool description, to call get_team_activity before starting work and share_session_update after. Real endpoints, real data behind them: sessions, current task, deviations. But it only happens if the model reads the instruction and follows it. Nothing enforces that the way the hook does.
One of these runs no matter what the model decides. The other is a request.
Put together, a hackathon team gets two kinds of visibility: one it can rely on, one it has to hope for. Solving the merge-conflict problem didn't require Codex to be trustworthy. It required git to be, which it already was.
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