- Added `markHandled` helper to prevent unhandled promise rejections in fire-and-forget browser tasks.
- Integrated `postmortem.markExpectedCleanupError` to distinguish between expected teardown aborts and actual runtime failures.
- Updated `runCmuxCode` and `WorkerCore` to propagate abort reasons via `ToolAbortError` cause chains.
- Modified `tab-protocol` and supervisor logic to signal expected cleanup states during tab release.
- Added test coverage for `ToolAbortError` wrapping and cause preservation.
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