Record: Coprime-Stride Loader + Full GPTQ + XSA-all — val_bpb 1.1133 (3-seed mean)

[Bortlesboat]

Summary

• val_bpb: 1.1133 (3-seed mean, std 0.0001)
• Artifact: ~15.89 MB (all seeds under 16,000,000 bytes)
• Eval time: ~85s (no TTT, sliding window stride=64)
• Built on PR #549 by @abaybektursun and PR #1060 by @dexhunter

3-Seed Results

Seed	Sliding BPB	Artifact
1337	1.1133	15,899,687
42	1.1132	15,881,359
999	1.1133	15,892,371
Mean +/- Std	1.1133 +/- 0.0001

What's New

1. GPTQ Reserve Optimization: Reduced calibration reserve from 14s to 9s (actual calibration takes ~8.4s), recovering ~55 extra training steps
2. FA3/FA2 Graceful Fallback: try/except import for flash_attn_interface with fallback to flash_attn

Stack

• Coprime-stride multi-shard data pipeline (PR Memmap multi-shard data pipeline + GPU prefetch + LeakyReLU² + Legal TTT + Parallel Muon #726 style)
• Full Hessian GPTQ with Cholesky error compensation
• XSA on all 11 layers
• BigramHash(2816x112), SmearGate, Partial RoPE(16d), LN Scale
• EMA(0.997), Parallel Muon + Parameter Banking
• FA3 Hopper, ~91ms/step, ~6,500 steps

Compliance

• Standard F.cross_entropy scoring (softmax, sum=1)
• No TTT, no mixer, no eval-built adaptation
• Artifact < 16,000,000 bytes (all 3 seeds)
• Training < 600s, eval < 600s
• Causal sliding-window evaluation (stride=64)

See README.md for full details.