docs: Document Nov 19 critical findings - database/Drift mismatch and P&L inflation

- Database shows only 3 v8 trades when Drift UI shows 6 trades
- One trade has 10x inflated P&L (81 vs 9 expected)
- Bot receiving ZERO API requests after 06:51 restart despite n8n executions succeeding
- Real v8 performance: ~2 LOSS (from Drift), database shows 20 profit (WRONG)
- Two issues: P&L compounding bug still active + n8n→bot connection broken
- Need to verify n8n workflow endpoints and fix external closure P&L calculation
- Common Pitfall #50 added to copilot-instructions.md

.github/copilot-instructions.md

@@ -2317,6 +2317,39 @@ trade.realizedPnL += actualRealizedPnL  // NOT: result.realizedPnL from SDK
       * This bug (#49): P&L compounding in external closure detection (fixed by not mutating trade.realizedPnL)
     - **Lesson:** In monitoring loops that run repeatedly, NEVER mutate shared state during calculation phases. Calculate locally, update shared state ONCE at the end. Immutability prevents compounding bugs in retry/race scenarios.
 
+50. **Database not tracking trades despite successful Drift executions (CRITICAL - Nov 19, 2025):**
+    - **Symptom:** Drift UI shows 6 trades executed in last 6 hours, database shows only 1 trade, bot logs show NO API requests
+    - **Root Cause:** Bot container restarted at 06:51 UTC, but trades executed BEFORE restart (00:20-05:56) weren't fully saved
+    - **Evidence:**
+      * n8n executions: 08:15, 06:45, 05:35, 01:45, 01:20 (all succeeded)
+      * Drift trades: 6 trades showing P&L from $18.42 to -$99.93 (total ~-$52 loss)
+      * Database: Only 3 v8 trades, with one showing $581 profit (10× inflated)
+      * Bot logs: ZERO API requests after 06:51 restart
+    - **Two Separate Issues:**
+      1. **Historical trades (before restart):** Database P&L values are inflated due to P&L compounding bug (Common Pitfall #49)
+         - One SHORT trade shows $581 profit in DB
+         - Actual: $138.88 → $137.74 = 0.82% move × $7232 position = **$59 expected**
+         - Inflated by ~10× due to P&L accumulation during external closure detection
+      2. **Recent trades (after restart):** Bot NOT receiving signals from n8n at all
+         - n8n shows successful executions at 08:15, 06:45
+         - Bot logs show ZERO incoming requests
+         - API is accessible (returns 401 on auth test)
+         - **Conclusion:** n8n is calling a DIFFERENT endpoint or the workflow changed
+    - **Impact:** 
+      * Cannot trust database P&L values for v8 trades
+      * System appears to be "working" in n8n but bot isn't actually trading
+      * Analytics dashboard showing completely wrong performance metrics
+    - **Temporary Status:** 
+      * Real v8 performance: ~$52 LOSS (from Drift UI)
+      * Database shows: $420 profit (WRONG - includes inflated $581 trade)
+      * Need to fix: P&L compounding bug + n8n→bot connection
+    - **Next Steps:**
+      1. Verify n8n workflow URLs point to correct bot endpoint
+      2. Fix P&L compounding in external closure detection (Common Pitfall #49 fix didn't work)
+      3. Correct historical database records with actual Drift transaction data
+      4. Add API request logging to catch silent failures
+    - **Lesson:** Always cross-reference database records with exchange UI after system changes. Container restarts can expose silent failures in the execution pipeline.
+
 46. **100% position sizing causes InsufficientCollateral (Fixed Nov 16, 2025):**
     - **Symptom:** Bot configured for 100% position size gets InsufficientCollateral errors, but Drift UI can open same size position
     - **Root Cause:** Drift's margin calculation includes fees, slippage buffers, and rounding - exact 100% leaves no room