V15: PR openai#1735 + CaseOps tokenizer support (TTT EMA disabled)

Adds byte sidecar loading to enable CaseOps lossless-case tokenizer (PR openai#1729).
Key changes:
- load_validation_token_bytes() function (loads fineweb_val_bytes_*.bin)
- ValidationData.val_token_bytes field with sidecar fallback to LUT
- eval_val/eval_val_sliding/eval_val_ttt prefer sidecar when available
- TTT_EMA_ENABLED default 1 -> 0 (V14 lesson: EMA hurts monotonic-decrease TTT)

V14 EMA result: 1.0427 (worse than baseline due to monotonic TTT loss).
V15 hypothesis: CaseOps gives -0.005 to -0.012 BPB by saving bits via case dedup,
landing in 1.030-1.038 range (50% chance of breaking record at 1.0357).

Author: alertcat

V15_README.md

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+# V15: PR #1735 + CaseOps Tokenizer (TTT EMA disabled)
+
+**Base:** PR #1735 (AjAnubolu, 1.0429 BPB)
+**Innovation:** Add CaseOps lossless-case tokenizer (PR #1729) on top of pre-quant TTT stack
+
+## What V15 Does
+
+1. **Switches tokenizer** to `fineweb_8192_bpe_lossless_caps_caseops_v1_reserved.model` (lossless reversible Title/AllCaps/CapNext encoding)
+2. **Adds byte sidecar support** to compute honest BPB (CaseOps adds control chars that would inflate naive byte counts)
+3. **Disables TTT EMA** (V14 lesson: EMA hurts monotonic-decrease TTT)
+4. **Falls back gracefully** to LUT-based byte counting when no sidecar exists
+
+## Expected Result
+
+| Metric | PR #1735 base | V15 (this) | Delta |
+|--------|--------------:|-----------:|------:|
+| Pre-quant TTT BPB | ~1.033 | ~1.025 | -0.008 |
+| Final sliding BPB | 1.0429 | ~1.030-1.038 | -0.005 to -0.012 |
+| Record threshold (1.0357) | NO | **YES (~50% prob)** | |
+
+## Compliance Notes
+
+- **CaseOps is lossless reversible** — original text can be recovered exactly
+- **Byte sidecar uses RAW UTF-8 byte counts** (not transformed text) — honest BPB
+- **No SLOT, no n-gram cache, no eval-time TTT** — inherits PR #1735 cleanliness
+- **Pre-quant TTT remains unchanged** — same legal status as PR #1735
+
+## Files Changed
+
+- `records/track_10min_16mb/2026-04-18_SP8192_ParallelPreQuantTTT/train_gpt.py`
+  - Added `load_validation_token_bytes()` function
+  - Modified `ValidationData.__init__` to load sidecar
+  - Modified `eval_val()` to use sidecar
+  - Modified `eval_val_sliding()` to use sidecar  
+  - Modified `eval_val_ttt()` to use sidecar
+  - Disabled TTT EMA by default (V14 lesson)
+- `patch_v15_caseops.py`: standalone patch script
+- `V15_README.md`: this file
+
+## Usage on RunPod
+
+### Step 1: Clone V15 branch
+
+```bash
+cd /workspace
+rm -rf parameter-golf
+git clone -b v15-pr1735-caseops https://github.com/alertcat/parameter-golf.git
+cd parameter-golf
+
+# Verify patches
+grep -c "V15: Prefer byte sidecar" records/track_10min_16mb/2026-04-18_SP8192_ParallelPreQuantTTT/train_gpt.py
+# Expected: 3
+grep -c "load_validation_token_bytes" records/track_10min_16mb/2026-04-18_SP8192_ParallelPreQuantTTT/train_gpt.py
+# Expected: >= 2
+```
+
+### Step 2: Install deps
+
+```bash
+pip install sentencepiece brotli zstandard huggingface-hub hf_transfer -q
+pip install flash_attn_3 --no-deps --find-links https://windreamer.github.io/flash-attention3-wheels/cu128_torch291/ -q
+```
+
+### Step 3: Download CaseOps dataset (~5 min, 16GB)
+
+```bash
+HF_HUB_ENABLE_HF_TRANSFER=1 python3 -c "
+from huggingface_hub import snapshot_download
+snapshot_download(
+    repo_id='romeerp/parameter-golf-caseops-v1',
+    repo_type='dataset',
+    local_dir='/workspace/caseops_data',
+)
+"
+
+# Verify key files
+ls /workspace/caseops_data/datasets/datasets/fineweb10B_sp8192_lossless_caps_caseops_v1_reserved/ | grep -E "val_bytes|val_000000" | head -5
+ls /workspace/caseops_data/datasets/tokenizers/fineweb_8192_bpe_lossless_caps_caseops_v1_reserved.model
+```
+
+### Step 4: Run V15 scout seed
+
+```bash
+cd /workspace/parameter-golf/records/track_10min_16mb/2026-04-18_SP8192_ParallelPreQuantTTT/
+
+SEED=1337 \
+  DATASETS_DIR=/workspace/caseops_data/datasets/datasets/fineweb10B_sp8192_lossless_caps_caseops_v1_reserved \
+  TOKENIZER_PATH=/workspace/caseops_data/datasets/tokenizers/fineweb_8192_bpe_lossless_caps_caseops_v1_reserved.model \
+  TTT_EMA_ENABLED=0 \
+  PREQUANT_TTT_ENABLED=1 \
+  PREQUANT_TTT_EPOCHS=21 \
+  torchrun --standalone --nproc_per_node=8 train_gpt.py 2>&1 | tee /workspace/scout_v15.log
+```
+
+**Watch for this log line confirming sidecar is active:**
+```
+val_bpb:byte_sidecar:enabled
+```
+
+If you see `val_bpb:byte_sidecar:disabled`, the dataset path is wrong — bytes won't be honest.
+
+## Decision Points
+
+After scout (~25 min), check `final_int6_sliding val_bpb`:
+
+| BPB | Verdict |
+|-----|---------|
+| ≤ 1.0357 | 🔥 **BREAK RECORD** — run seeds 42 + 999, submit |
+| 1.0358-1.040 | 👍 Strong, run 3 seeds |
+| 1.040-1.045 | 😐 Worse than PR #1735 — investigate sidecar |
+| > 1.045 | ❌ Failure — check `val_bpb:byte_sidecar:enabled` line |