test: cover direct browser stream cancellation

[rgarcia]

summary

• add an async telemetry stream that blocks until its consumer is canceled
• verify cancellation stops the consumer and closes the direct-routed response body
• assert the request reaches the browser VM telemetry path

tests

• pytest -q — 671 passed
• ruff check .
• pyright --pythonpath /tmp/kernel-python-venv/bin/python tests/test_browser_routing.py

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Note

Low Risk
Test-only addition with no runtime code changes; low risk beyond CI/test maintenance.

Overview
Adds test_async_telemetry_stream_cancellation_survives_direct_routing, which exercises AsyncKernel when telemetry/stream is allowlisted for direct browser VM routing.

The test uses a mock httpx.AsyncByteStream that blocks until the stream consumer is cancelled, then asserts the consumer raises CancelledError and the underlying response read/teardown completes (via read_stopped). It also pins that the request hits /browser/kernel/telemetry/stream on the cached browser route.

No production or SDK behavior changes—only regression coverage for cancelling long-lived SSE reads on direct-routed telemetry streams.

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