Catchup branch gated on first_accepted, but an earlier accepted gray tick
consumes the flag before a dark_* arrives, so the real prime-phase color
falls through to noise classification and no alert fires. Gate on
IDLE + dark_* alone — self-sufficient and correct.
Regression: 2 unit tests for _handle_tick + 1 integration test feeding
run_live a scripted gray→gray→dark_red→dark_red→light_red sequence.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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