feat: map DeepSeek Chat sampling robustness

experiments/deepseek/README.md

@@ -672,3 +672,85 @@ See `research/DEEPSEEK_V2_LITE_CHAT_COMPLETION_PROTOCOL.md` and
 `research/DEEPSEEK_V2_LITE_CHAT_COMPLETION_DEPTH_AUDIT.md` for the OOM
 amendment, task evaluators, completion table, depth curves, reproduction
 audit, artifact hashes, and claim boundaries.
+
+## Preregistered multi-seed Chat sampling
+
+`v2_lite_chat_sampling_probe.py` keeps the same four first-ranked sources,
+eight prompt conditions, 512-token cap, BF16 checkpoint, and offload contract.
+It enables the pinned official sampling values and explicitly disables top-k:
+
+```text
+do_sample=true · temperature=.3 · top_p=.95 · top_k=0
+4 sources × 8 SHA-256-derived seeds × 8 conditions = 256 outputs
+```
+
+The eight rows of one source remain in a fixed batch. They are batch-seed
+aligned, not common-random-number pairs: Transformers samples the whole batch
+with one `torch.multinomial` call.
+
+```bash
+PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True \
+PYTHONPATH=/path/to/transformers-4.41.2-deps \
+python -B experiments/deepseek/v2_lite_chat_sampling_probe.py \
+  --artifact-dir /path/to/deepseek-v2-lite-chat \
+  --reference-routing-json \
+    src/data/deepseek-v2-lite-routing-special-token-family-control.json \
+  --greedy-json src/data/deepseek-v2-lite-chat-completion-512.json \
+  --human-eval /path/to/HumanEval.jsonl.gz \
+  --gsm8k /path/to/gsm8k/test.jsonl \
+  --tnews /path/to/tnews/test.json \
+  --tnews-archive /path/to/tnews_public.zip \
+  --wikitext /path/to/wikitext-validation.parquet \
+  --base-seeds \
+    19683830 1560062173 3978401375 1280933274 \
+    1467459869 1297359489 2722953988 3330978061 \
+  --max-new-tokens 512 \
+  --gpu-memory 28GiB \
+  --cpu-memory 80GiB \
+  --output src/data/deepseek-v2-lite-chat-sampling.json
+```
+
+The independent evaluator preserves stopping, semantic terminal state,
+coverage, and correctness as separate ledgers. Exact duplicate code candidates
+reuse a cache keyed by candidate, task tests, and sandbox-harness hashes:
+
+```bash
+python -B experiments/deepseek/v2_lite_chat_sampling_evaluator.py \
+  --sampling-json src/data/deepseek-v2-lite-chat-sampling.json \
+  --human-eval /path/to/HumanEval.jsonl.gz \
+  --gsm8k /path/to/gsm8k/test.jsonl \
+  --sandbox-image \
+    python:3.11-alpine@sha256:25976e9d34a0fab1f278cae931f34c8303d97bf0c0d7f85b6b4dcf641d7702a4 \
+  --output src/data/deepseek-v2-lite-chat-sampling-eval.json
+```
+
+A fresh Python process reruns R0/R1. The reproduction comparer checks run
+seeds, prompt hashes, complete token IDs, text, stopping state, and CPU/CUDA
+RNG pre-state hashes:
+
+```bash
+python -B experiments/deepseek/v2_lite_chat_sampling_reproduction.py \
+  --formal-json src/data/deepseek-v2-lite-chat-sampling.json \
+  --rerun-json \
+    src/data/deepseek-v2-lite-chat-sampling-repro-r0r1.json \
+  --output \
+    src/data/deepseek-v2-lite-chat-sampling-reproduction.json
+```
+
+Formal results are 251/256 natural EOS and 242/256 globally unique complete
+token trajectories. Strict GSM8K exact is 62/64; HumanEval official-test pass
+is 63/64. These repeat one task per domain and are not benchmark estimates.
+The R0/R1 fresh-process rerun reproduces all eight preregistered fields in
+64/64 cells.
+
+```text
+formal  46c7edfce1409e798d6b0f06e905dd3a9d4ab6911acd8e42e2ec9d06d65345af
+eval    078f486e021ffd0e4af8ad942d001a9f2429933b2fb0fb3523b7d1da5b24c4d8
+rerun   72d050eace531bb38fb2592e39dc7f1b9c9003306c92c568dcd4acaaa691f6a0
+compare 4d59a775943459604ea2d9976bb3be01ff7b3b08d71eb0ca22c376122ef82d15
+```
+
+See `research/DEEPSEEK_V2_LITE_CHAT_SAMPLING_PROTOCOL.md` and
+`research/DEEPSEEK_V2_LITE_CHAT_SAMPLING_AUDIT.md` for seed derivation,
+smoke gates, source-condition diversity tables, edge-set comparisons, task
+failure cases, exact reproduction scope, primary sources, and non-claims.