v0.20.5: the wheel learns to coast

getevent settled what the wheel can and can't tell us: och1970_holl_key
advertises KEY_UP and KEY_DOWN and nothing else -- no REL_WHEEL, no
resolution, because the och1970 is a Hall latch the driver quantises into
clicks. There is no sub-detent position to read without a kernel driver
change, so all the nuance has to come from *when* the detents arrive.

So a detent is now an impulse into a velocity rather than a jump. The list
coasts and eases out, and an impulse is worth up to 8x more when detents come
30 ms apart than when they come 220 ms apart -- squared, so the gain stays out
of the way while you're hunting for one row. Measured on the device: one
unhurried detent moves about half a row, twelve fast ones move forty-odd.
Turning back the other way kills the coast first, so a correction bites
instead of fighting the glide.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SKXUgsBBwe3qaHEjeV8ubP

tasks-done.md

@@ -31,10 +31,17 @@ that *is* there plays exactly that song, shuffle or not.
       stats over MTP, ~840 KB of writes and a full tree walk with the progress
       line frozen. They report now, and `_write_index` reads `Art/` in one
       listing instead of a stat per album.
-- [x] **The wheel scrolls smoothly, and the other way** (`WheelScroll`). A
-      detent adds to a pixel debt that a Choreographer callback pays off a
-      fraction per frame, so one detent eases to a stop and a fast spin blends
-      into one movement instead of teleporting a row at a time. Direction
+- [x] **The wheel scrolls kinetically, and the other way** (`WheelScroll`;
+      v0.20.5 / andTunes 0.2.3 refined the first pass). `getevent -pl` settled
+      what's possible: `och1970_holl_key` advertises `KEY_UP KEY_DOWN` and
+      nothing else — no `REL_WHEEL`, no resolution, because the `och1970` is a
+      Hall latch the driver quantises into clicks. There is no sub-detent
+      position to read, so every bit of nuance comes from the *timing*. A
+      detent is an impulse into a velocity rather than a jump: the list coasts
+      and eases out, and an impulse is worth up to 8× more when detents arrive
+      30 ms apart instead of 220 ms. Measured on the device: one unhurried
+      detent moves about half a row, twelve fast ones move forty-odd. Turning
+      back the other way kills the coast first so a correction bites. Direction
       flipped in lists only; volume on the other screens is unchanged.
 
 ### Round 54 (2026-09-14) — one artist spelled two ways (v0.20.3, andTunes 0.2.1)