Goal sessions were showing stopped background-agent cards because the parent model used TaskStop after reading enough partial review output. That writes a killed task notification, which the desktop then rendered like a failure.
TaskStop and async agent launch guidance now make cancellation an exceptional action rather than a normal cleanup step. Stopped background-agent transcript cards also render as neutral interrupted events instead of error-styled failures.
Constraint: Background agent task notifications must remain truthful; killed tasks still surface as stopped instead of being hidden.
Rejected: Hide stopped notifications in /goal sessions | this would mask real user cancellations and runaway-task stops.
Confidence: medium
Scope-risk: narrow
Directive: Do not encourage parent turns to kill background agents only because partial output was read.
Tested: cd desktop && bun run test src/components/chat/MessageList.test.tsx -t "renders stopped background agents as neutral transcript events"
Tested: cd desktop && bun run lint
Tested: bun run check:server
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