Bounded Queues and Abort Signals

A queue without a cancellation path is a queue you cannot stop.

The AbortController contract gives every batch loop a single boolean to consult at a safe boundary, which is enough to guarantee the UI never lands in a half-applied state.

The Contract

• Check the signal before acquiring work.
• Check it again after every asynchronous boundary.
• Treat a cancelled run as a partial run and report it honestly.

Cancellation is a feature, not an error path.

Reporting partial progress keeps operator trust intact when a dispatch halts midway through a thousand recipients.