foxhunt/AGENT_P0_F3_TFT_SHAPE_BATCH2.md

Agent P0-F3: TFT Shape Fixes (Batch 2) - COMPLETE

Mission: Fix remaining 2 TFT INT8 shape bugs (225 → 256 elements)

Status: ✅ COMPLETE (100% success, 4/4 total fixes applied)

Execution Time: ~2 minutes

---

Summary

Successfully fixed the final 2 shape mismatches in tft_int8_latency_benchmark_test.rs, completing the shape fix wave. All 4 occurrences of the 225-element bug have been corrected to match the expected 256-element shape (2×128).

---

Changes Applied

File: ml/tests/tft_int8_latency_benchmark_test.rs

Fix 3/4 - Test 4 (Latency Percentile Distributions):

- let input_data = vec![0.5f32; 225];
+ let input_data = vec![0.5f32; 256];
  let input = Tensor::from_slice(&input_data, (2, 128), &device)?;

Location: Line 364 Function: test_latency_percentile_distributions() Impact: Fixes shape mismatch for consistency ratio validation

---

Fix 4/4 - Test 5 (Accuracy Preservation):

- let input_data = vec![scale; 225]; // 225 features
+ let input_data = vec![scale; 256]; // 256 elements (2*128 shape)
  let input = Tensor::from_slice(&input_data, (2, 128), &device)?;

Location: Line 442 Function: test_int8_accuracy_loss_under_5_percent() Impact: Fixes shape mismatch for accuracy validation (100 samples)

---

Validation

Compilation Status

$ cargo check
✅ Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.30s

Result: ✅ CLEAN BUILD (0 errors, 0 warnings)

---

Root Cause Analysis

The Bug Pattern

All 4 occurrences shared the same root cause:

Incorrect Assumption: Test authors assumed input shape should match feature count (225)

// WRONG: 225 features
let input_data = vec![0.5f32; 225];
let input = Tensor::from_slice(&input_data, (2, 128), &device)?;

Correct Shape: Input must match total elements in target shape

// CORRECT: 2 batch × 128 dims = 256 elements
let input_data = vec![0.5f32; 256];
let input = Tensor::from_slice(&input_data, (2, 128), &device)?;

Why This Happened

1. Feature confusion: 225 = total TFT input features (5 static + 10 known + 49 unknown + 161 Wave C)
2. Shape confusion: GRN test uses (2, 128) shape = 256 elements
3. Copy-paste error: All 4 tests duplicated the same incorrect size

---

Complete Fix Summary

Total Changes

Fix #	Test Function	Line	Old Value	New Value	Status
1	test_tft_int8_latency_under_5ms	~245	225	256	✅ P0-F1
2	test_int8_achieves_4x_speedup	~290	225	256	✅ P0-F2
3	test_latency_percentile_distributions	~364	225	256	✅ P0-F3 (this)
4	test_int8_accuracy_loss_under_5_percent	~442	225	256	✅ P0-F3 (this)

Completion: 4/4 fixes applied (100%)

---

Test Impact

Tests Now Ready for Execution

1. ✅ test_tft_fp32_baseline_latency (no change needed - already correct)
2. ✅ test_tft_int8_latency_under_5ms (fixed batch 1)
3. ✅ test_int8_achieves_4x_speedup (fixed batch 1)
4. ✅ test_latency_percentile_distributions (fixed batch 2)
5. ✅ test_int8_accuracy_loss_under_5_percent (fixed batch 2)
6. ✅ test_memory_footprint_reduction (no change needed - already correct)
7. ✅ test_full_tft_int8_end_to_end_latency (no change needed - infrastructure test)

Total: 7/7 tests ready (100%)

---

Next Steps

Immediate (P0-F4)

1. ✅ Shape fixes complete (4/4 locations)
2. ⏳ Run full test suite: cargo test -p ml tft_int8_latency -- --nocapture
3. ⏳ Validate all 7 benchmarks execute without panics
4. ⏳ Generate performance report (latency, speedup, accuracy metrics)

Follow-Up (P0-F5)

1. ⏳ Fix QAT device mismatch bug (4h estimated)
2. ⏳ Document gradient checkpointing workaround (1h estimated)
3. ⏳ Implement OOM recovery retry logic (8h estimated)

---

Files Modified

Production Code

• None (test-only fixes)

Test Code

• ml/tests/tft_int8_latency_benchmark_test.rs (+2 lines modified)

---

Deliverables

✅ All 4 shape fixes applied (225 → 256 elements) ✅ Clean compilation (0 errors, 0 warnings) ✅ Completion report (this document)

---

Agent Efficiency

• Estimated Time: 5 minutes (based on P0-F1, P0-F2 precedent)
• Actual Time: ~2 minutes
• Efficiency: 2.5x faster than estimate
• Method: MCP corrode tools (read_file, patch_file, check_code)

---

Conclusion

Status: ✅ SHAPE FIX WAVE COMPLETE

All 4 TFT INT8 shape bugs have been systematically fixed using the corrode MCP tools. The codebase now compiles cleanly and all 7 latency benchmark tests are ready for execution.

Next Agent (P0-F4): Execute full test suite and generate performance report.

Recommended Command:

cargo test -p ml tft_int8_latency -- --nocapture --test-threads=1

---

Agent: P0-F3 Wave: QAT P0 Fixes Date: 2025-10-25 Duration: ~2 minutes Result: ✅ SUCCESS (4/4 fixes complete, clean build)