The Architectural Shape Hint: A Spec-Time Trick That Lets 10 AI Agents Run in Parallel Without Stepping on Each Other

I run agent swarms now. Not "an agent" — agents , plural, in flight at once, each working on a different feature against the same repo. Ten agents per session is normal. Twenty isn't unusual when the spec is well-decomposed. The token math works, the wall-clock math works, the model latency hides inside the swarm because something is always landing while something else is still compiling. The economics make a strong case for parallel execution as the default. Until you hit the wall everyone hits