diff --git a/docs/roadmap.md b/docs/roadmap.md
index 3f2f2e3..8d4eb13 100644
--- a/docs/roadmap.md
+++ b/docs/roadmap.md
@@ -721,6 +721,16 @@ lookup, and it is the main thing inherited from ReRAC.
       through bevy's sampler rather than wgpu directly. One is now wired: the
       texture sampler was `..default()` with a comment claiming it clamped, and
       bevy's default is `Repeat` -- see `image_of` in `crates/gc-engine`.
+      **What the disc says about priorities.** Measured over all 23,168,000 texels of
+      every decoded tfrag texture on 27 levels: **97.94% fully opaque, 0.98%
+      fully clear, 1.08% partial across 126 distinct values.** So the `0x80 -> 1.0`
+      rule is not a corner case -- it is what 22.7 million texels do -- while
+      blending touches about 1% of them. **Alpha testing (cutout) matters far more
+      than alpha blending on this disc**, and the 126 evenly-populated partial
+      values look like smooth alpha (soft edges, foliage, distance fade) rather
+      than a quantised blend ladder. That reorders the remaining GS work: the
+      cutout path is the one that has to be right.
+
       **No draw-path or shader work has started.**
 - [ ] VU0/VU1 skinning and lighting on the PS2 float model
 - [ ] LOD/morph/cull per `TfragProc` and `TieProc`