ROOT CAUSE: placePerpOrder() only places orders on Drift order book, doesn't fill.
SOLUTION: placeAndTakePerpOrder() places AND matches against makers atomically.
Real Incident (Dec 31, 2025):
- Dec 30 18:17: SHORT opened at $124.36
- Dec 31 00:30: LONG signal received - should flip position
- Transaction confirmed but Solscan showed 'Place' not 'Fill'
- Position remained open, eventually hit SL twice
- Total loss: ~$40.21
Files changed:
- lib/drift/orders.ts (line 662): placePerpOrder → placeAndTakePerpOrder
- docs/COMMON_PITFALLS.md: Added Bug #90 documentation
Deployment: Dec 31, 2025 11:38 CET (container trading-bot-v4)
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