diff --git a/stacks/gemma4-charrp/.env.example b/stacks/gemma4-charrp/.env.example
index 03e8638..3b3a8ab 100644
--- a/stacks/gemma4-charrp/.env.example
+++ b/stacks/gemma4-charrp/.env.example
@@ -22,6 +22,21 @@ GEMMA4_MAX_NUM_SEQS=32
 # ⚠ THE NVFP4 QUANT, NOT THE BF16. /tank/aimodels/gemma4-26b-a4b-it-bf16 is the
 # QLoRA tuning base and is 48.10 GiB of weights — it does not fit beside gen.
 GEMMA4_MODEL=/tank/aimodels/gemma4-26b-a4b-it-nvfp4
+#
+# ACTIVATION-AXIS CONTROL, for one-off benching — swap this line, recreate:
+#   GEMMA4_MODEL=/tank/aimodels/gemma4-26b-a4b-it-nvfp4a16
+# Same NVFP4 weights and the same compressed-tensors loader, but 16-bit
+# activations. brokkr-smithy-dev's 2026-08-24 battery scored 12% on
+# contradiction detection with CoT off against gen's 81%, while every other
+# task sat at 100% — the shape 4-bit input activations would produce on the
+# most reasoning-dense task, so the finding is CONFOUNDED until this is run.
+# Two minutes down each way; port and both aliases are unchanged, so no
+# consumer config moves.
+#
+# ⚠ Only prithivMLmods/gemma-4-26B-A4B-it-NVFP4A16 is genuinely A16.
+# bg-digitalservices and ManniX-ITA both publish repos NAMED "NVFP4A16" whose
+# config.json declares input_activations num_bits 4. Check the field, not the
+# name, before ever substituting a different repo.
 
 GEMMA4_PORT=8016
 GEMMA4_GPU_ID=0