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>

4 files changed, 22 insertions, 7 deletions

diff --git a/desktop/Prefs.qml b/desktop/Prefs.qml
index dd2fdfc..d56b34c 100644
--- a/desktop/Prefs.qml
+++ b/desktop/Prefs.qml
@@ -34,12 +34,12 @@ Singleton {
 
     // The whole parsed object, so a write keeps keys this version does not
     // know about.
-    property var data: ({})
+    property var doc: ({})
 
     function setControls(list) {
         root.controls = Controls.normalize(list);
-        const out = Object.assign({}, root.data, { controls: root.controls });
-        root.data = out;
+        const out = Object.assign({}, root.doc, { controls: root.controls });
+        root.doc = out;
         file.setText(JSON.stringify(out, null, 2) + "\n");
     }
 
@@ -49,7 +49,7 @@ Singleton {
             const v = JSON.parse(file.text());
             if (v && typeof v === "object" && !Array.isArray(v)) parsed = v;
         } catch (e) {}
-        root.data = parsed;
+        root.doc = parsed;
         const next = "controls" in parsed ? Controls.normalize(parsed.controls) : Controls.defaults();
         // The watch also fires on our own write; compare so it is a no-op.
         if (JSON.stringify(next) !== JSON.stringify(root.controls)) root.controls = next;
@@ -61,9 +61,12 @@ Singleton {
         atomicWrites: true
         watchChanges: true
         printErrors: false
+        // printErrors is off for the missing-file read; a failed write still
+        // has to be heard, or the new order silently vanishes at restart.
+        onSaveFailed: error => console.warn("Prefs: writing", root.path, "failed:", error)
         onFileChanged: reload()
         onLoaded: root.reparse()
         // Missing file: the defaults, and nothing written.
-        onLoadFailed: { root.data = {}; root.controls = Controls.defaults(); }
+        onLoadFailed: { root.doc = {}; root.controls = Controls.defaults(); }
     }
 }
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.
diff --git a/desktop/island/ControlsPanel.qml b/desktop/island/ControlsPanel.qml
index a21b892..a7872d7 100644
--- a/desktop/island/ControlsPanel.qml
+++ b/desktop/island/ControlsPanel.qml
@@ -98,6 +98,10 @@ Column {
                     anchors.fill: parent
                     enabled: panel.editing
                     preventStealing: true
+                    // Both buttons and the wheel, so in edit mode nothing
+                    // reaches the tile: no drawer page, no volume change.
+                    acceptedButtons: Qt.LeftButton | Qt.RightButton
+                    onWheel: wheel => wheel.accepted = true
                     cursorShape: pressed ? Qt.ClosedHandCursor : Qt.OpenHandCursor
                     property real sx: 0
                     property real sy: 0
diff --git a/desktop/island/test_controls.js b/desktop/island/test_controls.js
index f84e472..b2db873 100644
--- a/desktop/island/test_controls.js
+++ b/desktop/island/test_controls.js
@@ -82,6 +82,9 @@ assert.strictEqual(C.step(1.48, 0.05, 1.5), 1.5);
 assert.strictEqual(C.step(0.98, 0.05, 1.0), 1);
 assert.strictEqual(C.step(0.1 + 0.2, 0.05, 1), 0.35);
 assert.strictEqual(C.step(undefined, 0.05, 1), 0.05);
+// Above the cap (set elsewhere): up leaves it, down steps from where it is.
+assert.strictEqual(C.step(1.2, 0.05, 1.0), 1.2);
+assert.strictEqual(C.step(1.2, -0.05, 1.0), 1.15);
 
 // slotAt: pitch 70, 4 columns, 7 tiles.
 assert.strictEqual(C.slotAt(35, 35, 70, 4, 7), 0);