You click Stop.

The spinner disappears. The input unlocks. You give the agent a different task.

Then the old tool finishes, and its result lands in the new conversation.

Or worse: the old tool sends the message you thought you had stopped.

These are different failures, and they need different fixes. One is about which run owns a result. The other is about whether an external system actually stopped doing work.

A single cancelled: true field hides that distinction surprisingly well.

Let's build a tiny TypeScript example that separates them. It stops waiting locally, rejects obsolete results, and deliberately proves that an uncooperative tool can still perform a side effect.

The interesting test is the one where the external write still happens.

Runnable code: https://github.com/bobbyhalljr/tiny-agent-cancellation-gate

1. There are three acknowledgments hiding behind Stop

Consider a hypothetical agent that starts a document export.…