Record: SmearGate BOS Fix + PR openai#1787 Base + Smear Gate + LQER Asymmetric + Phased TTT

val_bpb = 1.06128 | ~15.95 MB | 8xH100 SXM

Key Change: SmearGate BOS Document Boundary Fix
Builds on PR openai#1797 stack (PR openai#1787 base + SmearGate + LQER Asymmetric) but fixes the SmearGate cross-document leakage bug identified by @cocohearts in PR openai#1797 audit.

The bug: SmearGate 1-token causal lookback does not mask BOS positions, so the final token of document N smears into BOS of document N+1.

Credits
@nprime06 -- PR openai#1787 base stack
@romeerp -- CaseOps transform (PR openai#1729)
@dexhunter -- SmearGate + LQER (PR openai#1797)
@cocohearts -- Identifying SmearGate BOS bug
@abaybektursun -- Score-first TTT (PR openai#549)
@clarkkev -- GPTQ SDClip + SP8192 (PR openai#1394)

Author: aquariouseworkman

records/track_10min_16mb/2026-04-27_SmearGateBOSFix_PR1787Base_LQERAsym_PhasedTTT/README.md

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+# Record: SmearGate BOS Fix + PR #1787 Base + Smear Gate + LQER Asymmetric + Phased TTT
+
+**val_bpb = 1.06128** | **~15.95 MB** | 8xH100 SXM
+
+## Result
+
+| Seed | Pre-TTT BPB | Post-TTT BPB | Artifact (bytes) |
+|------|-------------|--------------|------------------|
+| 42   | 1.07406     | **1.06128**  | 15,952,086       |
+
+Merged SOTA (PR #1493): **1.0810 BPP**. Delta: **-0.0197 BPP**. Clears the 0.005-nat threshold.
+
+## Key Change: SmearGate BOS Document Boundary Fix
+
+Builds on PR #1797 stack (PR #1787 base + SmearGate + LQER Asymmetric) but fixes the **SmearGate cross-document leakage bug** identified by @cocohearts in PR #1797 audit.
+
+The bug: SmearGate 1-token causal lookback does not mask BOS positions, so the final token of document N smears into BOS of document N+1.
+
+The fix (applied in both forward_logits and forward_ttt):
+
+    bos_mask = (input_ids[:, 1:] == 1).unsqueeze(-1)
+    g = g.masked_fill(bos_mask, 0.0)
+
+## Technique Stack
+
+| Component | Origin |
+|-----------|--------|
+| CaseOps bijective case transform | PR #1729 / PR #1736 |
+| SparseAttnGate | PR #1787 (nprime06) |
+| SmearGate + BOS fix | PR #1797 + this submission |
+| LQER asymmetric rank-4 | PR #1797 |
+| Phased TTT (score-first, 3 phases) | PR #1394 / PR #1736 |
+| PolarNS + MIN_LR=0.1 + FusedCE | PR #1787 |
+| Full Hessian GPTQ + Brotli | PR #1019 / PR #1530 |
+
+## Architecture
+
+11L x 512d x 8H/4KV, MLP 4x, LeakyReLU(0.5)^2, Partial RoPE (16/64 dims), layerwise LN scale, tied embeddings, logit softcap=30.0. Depth recurrence: layers 3-5 looped x2 (activated at frac=0.35). Parallel residuals from layer 8. XSA on all 11 layers. SmearGate window=12.
+
+## Compliance
+
+- Artifact <= 16,000,000 bytes: 15,952,086 bytes
+- train_time <= 600s: 599.6s
+- eval_time <= 600s: 519.5s
+- Issue #1017 Conditions 1-4: All satisfied. SmearGate BOS mask ensures no cross-document leakage.
+
+## Credits
+
+- @nprime06 -- PR #1787 base stack
+- @romeerp -- CaseOps transform (PR #1729)
+- @dexhunter -- SmearGate + LQER (PR #1797)
+- @cocohearts -- Identifying SmearGate BOS bug
+- @abaybektursun -- Score-first TTT (PR #549)
+- @clarkkev -- GPTQ SDClip + SP8192 (PR #1394)