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- Add `or 0.0` defensive guard on `aircraft.heading` in `draw_aircraft` per spec (task 1.6) - Story 2-5 status: review → done - Sprint status updated: 2-5-per-aircraft-drawing done - Deferred work: add [2-5] default font 8px readability risk and [2-5] inline arrow geometry constants Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>