Update artifact index for issue41 substrate-only run

README.md

@@ -18,6 +18,21 @@ The Git repo keeps source code, configs, lightweight reports, and current narrat
 <!-- circuit-shotting-backup-index:start -->
 ## Artifact and Backup Locations
 
+### Issue 41 Mined MLP Substrate-Only Sufficiency - 2026-05-18
+
+- Primary backup bundle: `circuit-shotting/artifacts/mined_substrate_only/issue41_mined_substrate_only_20260518T103722Z`
+- Mirror bundle: `TokenBender/synth-data-en-pt-circuit` (`dataset`) at `issue41_mined_substrate_only_20260518T103722Z`
+- Source repo/branch/commit: `Occupying-Mars/circuit-shotting`, `tokenbender_experiments`, `c4354b4`
+- Pod/run root: `gentle-raven-34`, `/root/runs/issue41_mined_substrate_only_c4354b4`
+- Model/task: `tencent/HY-MT1.5-1.8B`, EN->PT translation
+- Held-out eval: NTREX EN->PT, 1,012 rows
+- Judge: `Unbabel/XCOMET-XXL` on one 96 GB RTX PRO 6000 Blackwell Workstation Edition GPU
+- Compared systems: `native_mined_substrate_only` and `actdelta_rank256_substrate_only`
+- Substrate: #39 `final_mix_top_3`, 5,898 MLP channels, about 3.0% of the HY-MT MLP channel universe
+- XCOMET summary: native substrate-only `0.2118839286819925` (`0.22814712205183943` recovery); ActDelta rank256 substrate-only `0.22047376124696297` (`0.23739626893520915` recovery)
+- Outcome: the 3% mined MLP substrate is highly destructive when removed but weak as a standalone MLP sufficiency circuit; ActDelta rank256 improves substrate-only recovery only slightly over native.
+
+
 ### Issue 39 ActDeltaLoRA MLP MVC - 2026-05-18
 
 - Primary backup bundle: `circuit-shotting/artifacts/actdelta_lora_mlp_mvc/issue39_actdelta_lora_mlp_mvc_20260518T011201Z`