model card: add the int8 build and state what it costs

README.md

@@ -31,6 +31,7 @@ end-to-end, with no privileged knowledge of which object is which.
 | `v7_mt_generalist_fp16.pt` | act one — one weight, eight tasks. 47.9 M params, 96 MB fp16. |
 | `v8_mt_colorsort_fp16.pt` | act one plus the ColorSort skill; the warm-start ancestor of the act-two policy. |
 | `colorsort/v15cs_frozen_fp16.pt` | act two — the delivered position-conditioned VLA. Frozen vision backbone so the grounder and the policy genuinely share one encoder: 48.1 M total. |
+| `colorsort/v15cs_frozen_int8.pt` | the same policy as W8A8 integer compute, 57.7 MB. Costs success — see below. Ships with `colorsort/v15cs_frozen_int8_params.json`, the per-layer quantisation parameter table. |
 | `colorsort/grounder_r4_mix20.pt` | act two — the MiniRT-Grounder heads (0.104 M params on a DINOv2-S backbone). Trained at `img_size=448`. |
 
 ## Numbers
@@ -77,9 +78,12 @@ particular silently costs eleven points if left at its default. The README has t
   `v8_mt_colorsort` has not. This is a design consequence — six generations of fine-tuning with zero
   base-task replay — not a defect, and it is recorded here so that comparing the two checkpoints
   does not lead to the wrong conclusion.
-- No integer-compute (int8) checkpoint of the act-two model is published. The conversion exists and
-  its calibration is correct, but its closed-loop behaviour has not been measured, and publishing it
-  on the strength of the single-task predecessor's result would be an unearned claim.
+- **The int8 build costs success and is labelled so.** fp16 26/100, int8 22/100; at the object level
+  58% against 47% over 249 objects. Both acceptance gates still pass, so it is usable — choose it for
+  the 40% size reduction, not because it is free. The four-point headline gap sits on the noise band
+  of a 100-episode run and read alone would suggest no effect; the paired per-seed comparison
+  (identical scenes and wording) shows int8 worse on 37 seeds and better on 17, p ~ 0.009. On the
+  single-task predecessor quantisation was genuinely free, which is why this is worth stating.
 
 ## Credit