fix(island): review findings in the controls panel

Edit mode let a right-click and the wheel through to the tile, so a
right-click opened the drawer and scroll changed volume, against the
spec. The drag area now takes both buttons and the wheel.

A scroll up on a level already above the cap, such as a mic set to 120%
elsewhere, snapped it down to the cap. The cap now only stops a step up.

Prefs logs a failed write, which printErrors off had silenced: the new
order would otherwise vanish at the next restart with no trace. Its
parsed object is renamed from data to doc, so it cannot shadow a base
property of that name.

The spec now says what was built: JSON.parse rather than a JsonAdapter,
and the helper list as it is.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/desktop/island/Controls.js b/desktop/island/Controls.js
index 39865b2..0ca2f6c 100644
--- a/desktop/island/Controls.js
+++ b/desktop/island/Controls.js
@@ -88,9 +88,14 @@ function fill(volume) {
 }
 
 // One scroll step, rounded to the percent so repeated steps do not drift.
+// The cap only stops a step up: a level already above it (set elsewhere,
+// e.g. a mic at 120% from pavucontrol) is left alone by up and stepped from
+// by down, never snapped to the cap.
 function step(volume, delta, max) {
-    const v = Math.round(((volume > 0 ? volume : 0) + delta) * 100) / 100;
-    return Math.max(0, Math.min(max, v));
+    const cur = volume > 0 ? volume : 0;
+    const v = Math.round((cur + delta) * 100) / 100;
+    if (delta < 0) return Math.max(0, v);
+    return Math.max(cur, Math.min(max, v));
 }
 
 // The slot a dragged tile lands in, from its centre in grid coordinates.