Add OrdersEA MT5 conversion notes

SESSION_SAVE_2026-03-22.md

@@ -211,3 +211,39 @@ This will:
 ### Commits:
 - `bf70b79` - Clean up OrdersEA.mq5
 - `c342966` - Clean up OrdersEA MT4 version
+
+---
+
+## Oanda MT4 Status & OrdersEA Conversion
+**Date:** March 24, 2026
+
+### Oanda Platform Status (Verified)
+- **MT4:** ✅ Fully supported globally (Oanda's primary platform)
+- **MT5:** ⚠️ Available only in select regions (Japan, UK, Europe, BVI)
+- **MT5 US:** ❌ NOT available for Oanda US clients
+- **Rating:** Oanda rated "Best MetaTrader 4 Broker 2026"
+
+### MT4 Environment Setup
+- Attempted Docker MT4 setup - image not publicly available
+- Created MT4 directory in Wine prefix: `~/mt5-docker/config/.wine/drive_c/Program Files/MetaTrader 4/`
+- **Note:** MT4 installer must be downloaded from Oanda directly (MetaQuotes removed public downloads)
+
+### OrdersEA Conversion to MT5
+**Files Created:**
+- `OrdersEA.mq5` - Converted MT5 version (v2.0)
+- `OrdersEA_MT4_Original.mq5` - Original MT4 backup
+- `OrdersEA_MT5_Converted.mq5` - Conversion reference
+
+**Key Conversions Made:**
+| MT4 | MT5 |
+|-----|-----|
+| `OrderSelect()` | `PositionGet()` / `HistorySelect()` |
+| `MarketInfo()` | `SymbolInfoDouble/Integer()` |
+| `Bid`, `Ask`, `Digits`, `Point` | `SymbolInfoDouble(_Symbol, SYMBOL_BID/ASK/POINT)` |
+| `OrderSend()` | `CTrade::OrderSend()` |
+| `OrderClose()` | `CTrade::PositionClose()` |
+| `int ticket` | `ulong ticket` |
+| `WindowExpertName()` | `MQLInfoString(MQL_PROGRAM_NAME)` |
+| `IsOptimization()` | `MQLInfoInteger(MQL_OPTIMIZATION)` |
+
+**Commit:** `c415cd9`