feat: audit DeepSeek Chat across sources

experiments/deepseek/README.md

@@ -754,3 +754,102 @@ 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.
+
+## Source-blocked cross-source Chat sampling
+
+`v2_lite_chat_cross_source_sampling_probe.py` reuses the audited sampling
+runtime but changes the coverage contract before any outputs are inspected:
+
+```text
+16 preregistered sources
+× 4 SHA-256-derived seeds
+× 4 conditions (system off/on × EOS/period)
+= 256 outputs
+```
+
+The four first-ranked sources in each of WikiText-2, TNEWS, HumanEval, and
+GSM8K come from the frozen routing-corpus selection contract. Source is the
+primary coverage unit; seed is a within-source repeat. The period condition is
+a directed Round-06 follow-up, not a blind independent confirmation.
+
+```bash
+PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True \
+PYTHONPATH=/path/to/transformers-4.41.2-deps \
+python -B \
+  experiments/deepseek/v2_lite_chat_cross_source_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 2101325316 2511573438 1677220094 2412346607 \
+  --max-new-tokens 512 \
+  --gpu-memory 28GiB \
+  --cpu-memory 80GiB \
+  --output \
+    src/data/deepseek-v2-lite-chat-cross-source-sampling.json
+```
+
+The independent evaluator uses the same pinned, networkless, read-only
+HumanEval sandbox and avoids pooling final-answer frequencies across different
+GSM8K tasks:
+
+```bash
+python -B \
+  experiments/deepseek/v2_lite_chat_cross_source_sampling_evaluator.py \
+  --sampling-json \
+    src/data/deepseek-v2-lite-chat-cross-source-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-cross-source-sampling-eval.json
+```
+
+The source-blocked analysis computes each contrast within source, then reports
+the four source directions in each domain. It deliberately emits no p-values
+or population confidence intervals:
+
+```bash
+python -B \
+  experiments/deepseek/v2_lite_chat_cross_source_sampling_analysis.py \
+  --sampling-json \
+    src/data/deepseek-v2-lite-chat-cross-source-sampling.json \
+  --evaluation-json \
+    src/data/deepseek-v2-lite-chat-cross-source-sampling-eval.json \
+  --reproduction-json \
+    src/data/deepseek-v2-lite-chat-cross-source-sampling-reproduction.json \
+  --output \
+    src/data/deepseek-v2-lite-chat-cross-source-sampling-analysis.json
+```
+
+A fresh Python process reruns R0 for all 16 sources. The existing reproduction
+comparer verifies the eight preregistered fields in all 64
+source-condition cells.
+
+Formal results are 250/256 natural EOS and 247/256 unique complete token
+trajectories. Strict task totals are Math 47/64 and Code 52/64, but the
+per-task totals range from 8/16 to 16/16 in both domains. Period shortens mean
+generation length for 11/16 sources. English is the important counterexample:
+the first source is −121 tokens while the other three are +44.5, +41, and
++1.375, so the domain mean is negative even though three of four sources are
+positive.
+
+```text
+formal   f013132485f27adce008f03f781bed9982efc0d7939f13faede01c9f6f3d7f7c
+eval     e88b274599fc5951561f9e5e7438fb4d6d25f341ae3bc4a2c4121877a0db8975
+rerun    143dc9d0f7c914db4781e36b1401cdc9fbc2971a0dca71188bab0f8cedb002a6
+compare  ec4a47894953f5d73bb62211b588632ef7032da0e915218992b7fc3ef9c2a556
+analysis d0dece388998fee419d34ff33f140695a9fedef6e79799cdf42eb283b047bc84
+compact  d0ab65646c6119bdeafeb451103dc6afebff3624a1e05f13a45a52ad965be1af
+```
+
+See `research/DEEPSEEK_V2_LITE_CHAT_CROSS_SOURCE_SAMPLING_PROTOCOL.md` and
+`research/DEEPSEEK_V2_LITE_CHAT_CROSS_SOURCE_SAMPLING_AUDIT.md` for the
+preregistered source frame, task matrices, source-direction contrasts,
+failure identities, hash chain, exact replay scope, and non-claims.