Downhill screens no longer shake on screen (t106)

docs/DESIGN.md

@@ -98,6 +98,10 @@ Details and numbers live in the code and in `docs/systems/`.
 
 ## Decisions
 
+- **Screen frames stay still (t106, 2026-10-30).** Removed visual shake from loaded
+  downhill screens in both looks: the owner dislikes it and wants consistency with flat
+  filters. Screens no longer shake visually; grain movement and sorting are unchanged.
+
 - **Transport matches the t45 belt (t105, 2026-10-30).** The owner approved the flat belt
   and asked for the other transport pieces to keep the same pace and flow through mixed lines.
   The flat belt stays unchanged: 30 cells/s, 30 grains/s with one layer and 90 grains/s with a
@@ -434,8 +438,8 @@ above, including:
 - **Conveyor drawing and sleep follow-up (t42/t43, 2026-10-26).** The owner wants visible
   rubber ribs on the actual cleat raster, filled corrugated far walls behind the load, and
   smooth continuous mesh with rails for inclined screens. Walls stop at the slope ends;
-  only loaded screens shake. Empty moving cleats must let chunks sleep. Keep pocket transport,
-  uphill throughput near 71 grains/s and exact sorting unchanged.
+  screens no longer shake visually (t106). Empty moving cleats must let chunks sleep. Keep
+  pocket transport, uphill throughput near 71 grains/s and exact sorting unchanged.
 
 - **Sidewall belts with moving cleats (t42, 2026-10-26; physics replaced by the entry below).** To replace the old full-column
   grip, use moving barrier lines rather than material cells: the barrier mask blocks normal
@@ -455,8 +459,8 @@ above, including:
   with one mesh-contact nudge every 4 ticks (15 downhill steps/s plus gravity). Unselected
   bars step on that same cadence; selected bars fall through. Flat filters retain their
   linear transport. Sorting both slope shapes in either mode conserves the complete mix.
-  Both looks use a sturdy mesh frame with a small tick-based shake only while loaded;
-  idle mesh has no running belt animation. No old uphill-save migration was added.
+  Both looks use a sturdy mesh frame that no longer shakes visually (t106);
+  mesh has no running belt animation. No old uphill-save migration was added.
 
 - **Screw conveyors stay, in every direction (2026-10-26).** The owner asked whether screw
   conveyors are still needed now that belts climb 45°, whether they're realistic, and what a