## Summary
A `chat.agent` turn that gets aborted mid-stream (stop generation, idle
suspend, cancellation) could surface a `TASK_RUN_UNCAUGHT_EXCEPTION` —
`TypeError: Invalid state: Unable to enqueue` — in the dashboard. The
run kept working, but the exceptions were loud and confusing.
## Root cause
The realtime stream writer batches chunks through
`@s2-dev/streamstore`'s `BatchTransform`, which holds them for a short
linger window before flushing. When the turn's abort signal fires while
a record is still buffered, the stream's writable is aborted and the
transform's readable controller is closed — but the pending linger
`setTimeout` still fires and calls `controller.enqueue()` on the dead
controller, throwing from a timer callback where nothing can catch it.
Fixed upstream in `@s2-dev/streamstore@0.22.10`, which wraps the linger
flush in a try/catch that discards the closed-controller error. This
bumps the dependency across core, the CLI, and the webapp, and adds a
regression test against the real `BatchTransform`.
Verified end-to-end: a mid-stream stop that previously failed the run
with `TASK_RUN_UNCAUGHT_EXCEPTION` now leaves the run healthy.
Eric Allam
2dd9f37b40