Documents the critical P&L compounding bug fixed in commit 6156c0f where
trade.realizedPnL mutation during external closure detection caused 15-20x
inflation of actual profit/loss values.
Includes:
- Root cause: Mutating trade.realizedPnL in monitoring loop
- Real incident: $6 actual profit → $92.46 in database
- Bug mechanism with code examples
- Why previous fixes (Common Pitfalls #27, #48) didn't prevent this
- Fix: Don't mutate shared state during calculations
- Related to other P&L compounding variants for cross-reference
becd5631e7