Initial commit: E4B-MarkBase model integration with passing tests
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- E4B-MarkBase model (42 layers, 4.4GB) loaded successfully - All Phase 1-6 tests passed (model loading, forward pass, vision/audio towers, token generation, performance) - All stress tests passed (5/5 in 127.6s) - Concurrent inference - Memory stress (67.5 tok/s, 0 NaN) - Continuous generation - Batch processing - Long-running stability - Swift Metal inference engine with multimodal support
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MarkBase Admin
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# 26B-A4B MoE Debug Summary - Current Status
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## Test Date
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2026-06-20 22:13-22:15
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## ✅ Successes
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### 1. Model Loading - COMPLETE SUCCESS ⭐⭐⭐⭐⭐
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```
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Load time: 51.818s
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Layers: 30 (ALL MoE ✓)
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Experts: 128/128 per layer ✓
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Total tensors: 1697
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Status: Test passed
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```
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### 2. Router Structure Verification - COMPLETE SUCCESS ⭐⭐⭐⭐⭐
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```
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Router components: All present ✓
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Expert components: All present ✓
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Router weights: 8-bit, correct dimensions ✓
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Expert weights: 4-bit, correct structure ✓
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Router scale: 31.25 ⚠️ (potential issue)
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Status: Test passed
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```
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## ⚠️ Issues Found
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### 1. Token Generation - HANGS ⚠️⚠️⚠️
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**Symptoms**:
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- Generation test hangs
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- Timeout after 30s (no response)
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- Likely numerical issue in forward pass
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**Root Cause** (Hypothesis):
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- **routerScale = 31.25 might be too large**
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- Similar to 26B-Standard scales issue
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- May cause softmax overflow or NaN
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- Needs normalization (divide by hiddenSize?)
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### 2. Router Scale Value - POTENTIAL BUG ⚠️⚠️
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**Current value**: routerScale = 31.25
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**Question**: Is this already normalized or raw value?
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**Similar issue (26B-Standard)**:
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```
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26B-Standard scales:
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- Raw: ~120
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- Problem: Too large
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- Fix: Normalize by hiddenSize (120/2816 = 0.0426)
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- Result: Fixed NaN
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26B-A4B routerScale:
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- Current: 31.25
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- Hypothesis: May need normalization
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- Potential fix: 31.25/2816 = 0.011
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```
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## 📊 Test Results Summary
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| Test | Status | Duration | Result |
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|------|--------|----------|--------|
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| Model Loading | ✅ PASSED | 51.818s | All 30 layers loaded with MoE |
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| Router Structure | ✅ PASSED | 1.0s | All components verified |
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| Token Generation | ❌ HANGS | 30s+ timeout | No response, likely NaN |
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| Forward Pass | ⏳ Not tested | - | Needs separate test |
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## 🔧 Proposed Fixes
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### Fix 1: Router Scale Normalization ⭐⭐⭐⭐⭐
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**Code location**: Model.swift:508-519
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**Current code**:
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```swift
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if let rsDesc = allTensors.first(where: { $0.name == "\(prefix).router.scale" }) {
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let rsData = try rsReader.read(tensor: rsDesc)
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let rsFloats = SafeTensorsReader.bf16ToFloat32(rsData)
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routerScale = rsFloats.first ?? 1.0 // Raw value
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}
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```
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**Proposed fix**:
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```swift
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if let rsDesc = allTensors.first(where: { $0.name == "\(prefix).router.scale" }) {
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let rsData = try rsReader.read(tensor: rsDesc)
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let rsFloats = SafeTensorsReader.bf16ToFloat32(rsData)
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let rawRouterScale = rsFloats.first ?? 1.0
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// Normalize by hiddenSize (similar to scales normalization)
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routerScale = rawRouterScale / Float(hiddenSize) // 31.25/2816 = 0.011
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}
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```
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**Expected result**:
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- routerScale = 0.011 (smaller, stable)
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- Softmax won't overflow
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- Generation should work
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**Confidence**: ⭐⭐⭐⭐⭐ High (based on 26B-Standard fix pattern)
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### Fix 2: Add NaN Checks ⭐⭐⭐⭐
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**Add debug prints in Layer.swift moeForward**:
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```swift
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// After router computation
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let routerData = engine.readFloats(from: temps.gate, count: numExperts)
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print("Router logits: max=\(routerData.max()), min=\(routerData.min())")
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// After scaling
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var scaled = routerData.map { $0 * routerScale }
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print("Scaled logits: max=\(scaled.max()), min=\(scaled.min())")
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// After softmax
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print("Softmax weights: sum=\(sum)")
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```
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**Purpose**:
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- Identify where NaN occurs
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- Verify router computation
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- Debug numerical issues
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### Fix 3: Expert Scale Normalization ⭐⭐⭐
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**Similar to 26B-Standard scales fix**:
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If router fix doesn't work, expert scales might also need normalization:
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```swift
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// In loadExpertGroup
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let normalizedScales = scales / Float(expertInDim)
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```
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## 🎯 Next Steps
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### Immediate (Priority 1)
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1. ✅ **Apply router scale normalization**
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- Edit Model.swift:508-519
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- Add normalization: routerScale /= hiddenSize
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- Test generation
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2. ⏳ **Test generation with fix**
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- Run MoEDebugTests/test26BA4BSimpleGenerationDebug
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- Expect: generation works
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- If works: Document fix
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### If Fix Works (Priority 2)
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3. ✅ **Document router scale fix**
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- Create validation report
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- Compare with 26B-Standard fix
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- Document normalization pattern
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4. ✅ **Run full benchmark**
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- Test token generation speed
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- Compare with 26B-Standard (40 tok/s)
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- Memory usage
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### If Fix Doesn't Work (Priority 3)
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5. ⚠️ **Debug forward pass**
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- Add NaN checks
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- Test router computation
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- Test expert selection
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6. ⚠️ **Check other issues**
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- Expert scales normalization
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- Metal kernels
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- Forward pass sequence
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## 📈 Expected Timeline
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**With router fix**:
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- Fix implementation: 5 minutes
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- Testing: 5-10 minutes
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- Documentation: 5 minutes
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- **Total**: 15-20 minutes ⭐⭐⭐⭐⭐
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**If router fix doesn't work**:
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- Additional debugging: 30-60 minutes
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- Multiple attempts: 1-2 hours
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- **Total**: 2-3 hours ⚠️⚠️
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## 📊 Comparison: MoE vs Dense
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| Model | Type | Load Status | Load Time | Generation | Speed |
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|-------|------|-------------|-----------|------------|-------|
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| 26B-Standard | Dense | ✅ Works | 5.3s | ✅ Works | 40 tok/s |
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| 31B-IT | Dense | ✅ Works | 63.8s | ✅ Works | 11.7 tok/s |
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| **26B-A4B** | **MoE** | **✅ Works** | **51.818s** | **⚠️ Fix needed** | **Expected: 20-30 tok/s** |
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## 🎓 Lessons Learned
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1. **MoE implementation already complete** ✅
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- No need for 3-5 days implementation
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- Code was ready, just needed testing
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2. **Router scale needs investigation** ⚠️
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- Similar to 26B-Standard scales issue
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- Normalization pattern applies to MoE too
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3. **Test incrementally** ⭐⭐⭐⭐⭐
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- First test loading (passed)
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- Then test structure (passed)
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- Now test generation (issue found)
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- Debug systematically
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## 💡 Recommendation
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**Apply router scale normalization NOW** ⭐⭐⭐⭐⭐
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**Reasons**:
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- High confidence fix (based on 26B-Standard pattern)
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- Quick to implement (5 minutes)
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- Likely to work (similar issue pattern)
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- If works → complete success
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- If fails → debug further
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**Time investment**: 15-20 minutes
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**Potential reward**: MoE model working!
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**Risk**: Low (if fails, we learn more)
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---
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## Files Created
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**Test reports**:
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- `/Users/accusys/MarkBase12B/26B_A4B_LOADING_SUCCESS.md`
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- `/Users/accusys/MarkBase12B/26B_A4B_ROUTER_SCALE_ANALYSIS.md`
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- `/Users/accusys/MarkBase12B/26B_A4B_MOE_DEBUG_SUMMARY.md`
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**Test code**:
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- `/Users/accusys/MarkBase12B/Tests/G12BTests/MoEDebugTests.swift`
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- `/Users/accusys/MarkBase12B/Tests/G12BTests/MoEForwardTests.swift`
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**Test logs**:
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- `/Users/accusys/MarkBase12B/26B_A4B_LOADING_TEST.log`
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- `/Users/accusys/MarkBase12B/MOE_ROUTER_STRUCTURE_TEST.log`
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---
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## Summary
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**✅ Major progress**: MoE model loading and structure verified
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**⚠️ Blocking issue**: Generation hangs, likely router scale too large
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**🔧 Proposed fix**: Normalize routerScale by hiddenSize (31.25/2816)
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**📊 Confidence**: High (⭐⭐⭐⭐⭐) based on 26B-Standard fix pattern
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**⏱️ Expected time**: 15-20 minutes to test fix
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**🏆 Potential outcome**: First working MoE model!
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