critical: Bug #90 - Use placeAndTakePerpOrder for immediate MARKET order fills

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)

docs/COMMON_PITFALLS.md

@@ -99,6 +99,7 @@ This document is the **comprehensive reference** for all documented pitfalls, bu
 | 71 | 🔴 CRITICAL | Revenge System | Dec 3, 2025 | Revenge system missing external closure integration |
 | 72 | 🔴 CRITICAL | Telegram | Dec 4, 2025 | Telegram webhook conflicts with polling bot |
 | 89 | 🔴 CRITICAL | Drift Protocol | Dec 16, 2025 | Drift fractional position remnants after SL execution |
+| 90 | 🔴 CRITICAL | Drift Protocol | Dec 31, 2025 | placePerpOrder only places orders, doesn't fill - use placeAndTakePerpOrder |
 
 ---
 
@@ -1642,6 +1643,112 @@ if (fractionalPositions.length > 0) {
 
 ---
 
+### Pitfall #90: placePerpOrder Only Places Order, Doesn't Fill - Use placeAndTakePerpOrder (CRITICAL - FIXED Dec 31, 2025)
+
+**Severity:** 🔴 CRITICAL  
+**Category:** Drift Protocol / SDK  
+**Date:** Dec 31, 2025  
+**Financial Impact:** ~$40+ loss from failed position flip
+
+**Symptom:**
+- Position flip signal received (LONG to close SHORT and open LONG)
+- Close transaction confirms on-chain
+- BUT position remains open on Drift
+- n8n shows "Flip failed - position did not close"
+- Solscan shows transaction as "Place long X SOL perp order at price 0" (NOT a fill)
+
+**Root Cause:**
+The bot was using `driftClient.placePerpOrder()` which only **places** an order on the Drift order book. For MARKET orders to execute immediately, you must use `driftClient.placeAndTakePerpOrder()` which places the order AND matches it against makers atomically.
+
+**Code Evidence (before fix):**
+```typescript
+// lib/drift/orders.ts line 662 (BROKEN)
+const txSig = await retryWithBackoff(async () => {
+  return await driftClient.placePerpOrder(orderParams)  // ❌ Only places order!
+}, 3, 8000)
+```
+
+**Real Incident (Dec 31, 2025):**
+- Dec 30 18:17 CET: SHORT opened at $124.36 via TradingView signal
+- Dec 31 00:30 CET: LONG signal received - should flip position
+- Close transaction: 5E713pD6... confirmed on-chain
+- Solscan shows: "Place long 24.72 SOL perp order at price 0" (order placed, NOT filled)
+- Position remained open: 24.72 SOL SHORT still on Drift
+- n8n logs: "Flip failed - position did not close"
+- Dec 31 05:01 CET: SHORT hit SOFT_SL at $125.30 (P&L: -$23.29)
+- Dec 31 05:01 CET: Autosync detected orphan, created new trade record
+- Dec 31 10:35 CET: Autosync position hit SL at $125.99 (P&L: -$16.92)
+- **Total loss from bug: ~$40.21**
+
+**THE FIX (Dec 31, 2025):**
+```typescript
+// lib/drift/orders.ts line 662 (FIXED)
+// CRITICAL FIX (Dec 31, 2025 - Bug #90): Use placeAndTakePerpOrder instead of placePerpOrder
+// ROOT CAUSE: placePerpOrder only PLACES an order on the Drift order book.
+// For MARKET orders, the order sits there waiting for a taker, which may never come.
+// SOLUTION: placeAndTakePerpOrder places the order AND fills it against makers atomically.
+// This ensures MARKET orders execute immediately instead of just being placed.
+console.log('🚀 Placing market close order with IMMEDIATE FILL (placeAndTakePerpOrder)...')
+const txSig = await retryWithBackoff(async () => {
+  return await driftClient.placeAndTakePerpOrder(orderParams)  // ✅ Places AND fills!
+}, 3, 8000)
+```
+
+**Drift SDK Method Comparison:**
+| Method | Behavior | Use Case |
+|--------|----------|----------|
+| `placePerpOrder()` | Places order on order book only | LIMIT orders waiting for fill |
+| `placeAndTakePerpOrder()` | Places AND matches against makers | MARKET orders needing immediate fill |
+
+**Key Evidence from Solscan:**
+- Transaction: 5E713pD6N4c4BbvfY1vL77g17pDPQZqhTFvWXF7YnELN...
+- Action: "Place long 24.72 SOL perp order at price 0"
+- Result: Order placed on book but NOT filled
+- Position: Remained open (24.72 SOL SHORT)
+
+**Why This Is Critical:**
+- **Position flips fail silently** - transaction confirms but position doesn't close
+- **Risk accumulates** - trader thinks position flipped, but exposure continues
+- **Opposite signal never opens** - LONG can't open because old SHORT still exists
+- **Cascade of losses** - unprotected position eventually hits SL with larger loss
+
+**Prevention Rules:**
+1. ALWAYS use `placeAndTakePerpOrder()` for MARKET orders that need immediate fill
+2. ALWAYS verify position size on Drift after close transactions
+3. CHECK Solscan for "Place" vs "Fill" actions in transaction details
+4. NEVER trust transaction confirmation alone - verify position state
+
+**Red Flags Indicating This Bug:**
+- Transaction confirms but position still shows on Drift
+- Solscan shows "Place" instead of "Fill" action
+- n8n logs "Flip failed - position did not close"
+- `needsVerification: true` returned from close operation
+- Position continues moving after supposed close
+
+**Verification After Fix:**
+```bash
+# Check container is running with fix
+docker inspect trading-bot-v4 --format='{{.State.StartedAt}}'
+# Should be after Dec 31, 2025 10:38 UTC
+
+# Test next close operation
+docker logs -f trading-bot-v4 | grep "placeAndTakePerpOrder\|IMMEDIATE FILL"
+```
+
+**Files Changed:**
+- lib/drift/orders.ts (line 662): `placePerpOrder` → `placeAndTakePerpOrder`
+- Added console.log for visibility: "🚀 Placing market close order with IMMEDIATE FILL..."
+
+**Git Commit:** [PENDING] "critical: Bug #90 - Use placeAndTakePerpOrder for immediate MARKET order fills"
+
+**Deployment:** Dec 31, 2025 11:38 CET (container trading-bot-v4)
+
+**Status:** ✅ FIXED AND DEPLOYED
+
+**Lesson Learned:** The Drift SDK has TWO methods for placing perp orders. `placePerpOrder()` only places orders on the book (suitable for LIMIT orders). `placeAndTakePerpOrder()` places AND fills immediately (required for MARKET orders). Always use the latter for market orders to ensure immediate execution. Transaction confirmation does NOT mean the order was filled - verify position state after close operations.
+
+---
+
 ## Appendix: Pattern Recognition
 
 ### Common Root Causes
@@ -1672,5 +1779,5 @@ if (fractionalPositions.length > 0) {
 
 ---
 
-**Last Updated:** December 4, 2025  
+**Last Updated:** December 31, 2025  
 **Maintainer:** AI Agent team following "NOTHING gets lost" principle

lib/drift/orders.ts

@@ -644,7 +644,7 @@ export async function closePosition(
       }
     }
     
-    // Prepare close order (opposite direction) - use simple structure like v3
+    // Prepare close order (opposite direction)
     const orderParams = {
       orderType: OrderType.MARKET,
       marketIndex: marketConfig.driftMarketIndex,
@@ -655,14 +655,26 @@ export async function closePosition(
       reduceOnly: true, // Important: only close existing position
     }
     
-    // Place market close order using simple placePerpOrder (like v3)
+    // CRITICAL FIX (Dec 31, 2025 - Bug #89): Use placeAndTakePerpOrder instead of placePerpOrder
-    // CRITICAL: Wrap in retry logic for rate limit protection
+    // 
-    logger.log('🚀 Placing REAL market close order with retry protection...')
+    // ROOT CAUSE: placePerpOrder only PLACES an order on the order book.
+    // For MARKET orders, the transaction confirms when the order is placed, NOT when it's filled.
+    // This caused the flip operation to fail - close tx confirmed but position never closed.
+    // 
+    // SOLUTION: placeAndTakePerpOrder places the order AND fills it against makers atomically.
+    // This guarantees the position is closed when the transaction confirms.
+    //
+    // Evidence: Solscan showed tx 5E713pD6... as "Place long 24.72 SOL perp order at price 0"
+    // - The order was placed on the book but never filled
+    // - Position remained open despite "confirmed" transaction
+    //
+    // See: https://github.com/drift-labs/drift-vaults/blob/main/tests/testHelpers.ts#L1542
+    console.log('🚀 Placing market close order with IMMEDIATE FILL (placeAndTakePerpOrder)...')
     const txSig = await retryWithBackoff(async () => {
-      return await driftClient.placePerpOrder(orderParams)
+      return await driftClient.placeAndTakePerpOrder(orderParams)
     }, 3, 8000) // 8s base delay, 3 max retries
     
-    logger.log(`✅ Close order placed! Transaction: ${txSig}`)
+    console.log(`✅ Close order executed! Transaction: ${txSig}`)
     
     // CRITICAL: Confirm transaction on-chain to prevent phantom closes
     // BUT: Use timeout to prevent API hangs during network congestion