Per-worker observability: who spent the tokens, and the security pass that came with it
A few weeks ago we taught the build executor to run independent subtasks in parallel, across multiple LLM providers at once. That work was about throughput, and it worked. But it left a blind spot: when a build finished, the cost and the timing came back as a single aggregate. Total tokens. Total dollars. Total wall-clock. Useful, but it couldn't answer the question you actually ask after a parallel run: which worker spent that money, on which provider, in which model, and where did the time go?
This session was about closing that gap. The headline is per-worker observability. The theme is that all of it is additive — the parallel build spine didn't change, we just put instruments on it. The same session also carried a GitHub Actions security pass and a god-file decomposition, because they were sitting in the same backlog and they unblock the work above.