CRITICAL LESSON LEARNED (Dec 5, 2025):
Document the data analysis disaster caused by MFE/MAE stored in mixed units.
What Happened:
- Analyzed blocked vs executed signals to improve win rate
- SQL showed executed signals: 20.15% avg MFE (appeared excellent)
- Implemented "optimizations" based on this data:
* Tighter ATR multipliers (2.0→1.5, 4.0→3.0)
* Higher TP1 close (60%→75%)
* Increased leverage (1×→5×)
- User questioned: Why doesn't TP1 hit if it's 20% MFE?
- Investigation: Only 2/11 trades reached TP1 price target
- Root cause: Old records stored MFE in DOLLARS, new in PERCENTAGES
- TRUE MFE: 0.76% (long), 1.20% (short) - NOT 20%!
- 26× inflation due to unit mismatch
Why This Matters:
- This is a REAL MONEY system - wrong analysis = wrong trades = losses
- MFE/MAE used for critical decisions (exit timing, quality validation)
- Agent made "data-driven" optimizations on 26× inflated data
- All changes had to be reverted (commits a67a338, f65aae5)
MANDATORY SQL Pattern:
- ALWAYS filter by createdAt >= '2025-11-23' for MFE/MAE queries
- OR recalculate from prices (maxFavorablePrice - entryPrice)
- NEVER trust raw AVG(maxFavorableExcursion) without date filter
Prevention:
- Verify stored vs calculated values before ANY MFE/MAE analysis
- Check sample of recent vs old records to detect unit changes
- Document data format changes in Common Pitfalls immediately
Related:
- Common Pitfall #54: Original MFE/MAE units bug (Nov 23, 2025)
- Revert commit: a15f17f
- Incorrect optimization: a67a338, f65aae5
8ec4eb0782