Cross-domain design exercise

Here is the prompt to rehearse cold: design the pipeline that authenticates a user, calls SCM, runs the agent and emits a webhook on completion. It forces all four domains into one diagram with clean contracts between them.

This is close to what the paid onsite working session actually feels like - a real system, built with the team, no AI assistance beyond autocomplete. The artifact you want in your head is the data flow plus the failure mode at every hop.