Root cause of test failure: BROWSE_IDLE_TIMEOUT is in milliseconds, not
seconds. '600' = 0.6 seconds, server died immediately after health check.
Fixed to '600000' (10 minutes).
Also: use 'pipe' stdio instead of file descriptors (closing fds kills child
on macOS/bun), catch ConnectionRefused on poll retry, 4 min poll timeout
for the multi-step opus task.
Test passes: agent navigates to HN, reads comments, identifies most
insightful one, highlights it with orange CSS, stops. 114s, $0.00.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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