ui: single rounding knob, fix balloon-shaped cards

New settings/ui.nix holds `radius` as the one source of truth. Theme
derives radiusCard/Small/Tiny from it and hyprland's decoration.rounding
reads the same value, so one number rescales the whole desktop —
previously the shell and the window corners were unrelated constants,
which is why doubling Theme.radius left windows at 8.

Cards were using the SAME radius as the panel containing them. Nested
corners need outer − gap; matching them makes the inner corner
over-round for its size, which is the inflated/balloon look. All nine
inner surfaces now use radiusCard (radius − panelGap). Invisible at
r=8, obvious at r=32.

Radius 32 -> 24.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

settings/hyprland.nix

@@ -3,6 +3,7 @@
 let
   isMacbook = config.networking.hostName == "FredOS-Macbook";
   isGaming  = !isMacbook;
+  ui = import ./ui.nix;   # shared corner-rounding knob
 
 in
 {
@@ -114,7 +115,8 @@ in
             };
 
             decoration = {
-              rounding = 8;
+              # tracks Theme.radius via settings/ui.nix
+              rounding = ui.radius;
               blur = {
                 enabled = true;
                 size = 1;

settings/quickshell.nix

@@ -4,6 +4,7 @@
 { config, pkgs, lib, ... }:
 let
   isMacbook = config.networking.hostName == "FredOS-Macbook";
+  ui = import ./ui.nix;   # shared corner-rounding knob
 in
 {
   config = lib.mkIf (lib.elem config.networking.hostName [ "FredOS-Gaming" "FredOS-Macbook" ]) {
@@ -180,9 +181,19 @@ in
                 // here, not in ~15 places. Wide enough for the stacked HH/mm
                 // clock, which is what sets the floor.
                 readonly property int barWidth: 46
-                readonly property int radius: 32       // cards, panels, dropdowns
+                // ── Rounding. ONE knob: settings/ui.nix `radius`. Everything
-                readonly property int radiusSmall: 24  // workspace dots, pill buttons
+                // below derives from it, and hyprland's window rounding reads
-                readonly property int radiusTiny: 16   // hover rows, action chips
+                // the same value, so changing that one number rescales the
+                // roundness of the entire desktop.
+                readonly property int radius: ${toString ui.radius}   // panels, dropdowns, screen cutout
+                // Concentric, NOT a factor: a card inside a panel needs the
+                // panel's radius MINUS the gap between them. Give it the same
+                // radius as its container and the inner corner is over-round
+                // for its size — the card reads as inflated/balloon-like,
+                // invisible at r=8 and obvious by r=32.
+                readonly property int radiusCard: radius - panelGap
+                readonly property int radiusSmall: Math.round(radius * 0.75) // pill buttons, workspace dots
+                readonly property int radiusTiny: Math.round(radius * 0.5)   // hover rows, action chips
                 readonly property int cardPad: 8       // card inner padding (inset = 2×)
                 readonly property int panelGap: 8      // gap between panel border and cards (all dropdowns/menus/toast)
 
@@ -311,7 +322,7 @@ in
                             anchors.horizontalCenter: parent.horizontalCenter
                             width: 280
                             height: 44
-                            radius: Theme.radius
+                            radius: Theme.radiusCard
                             color: Theme.cardBg
                             border.width: Theme.borderWidth
                             border.color: pam.active ? Theme.base0D
@@ -744,7 +755,7 @@ in
                 component Card: Rectangle {
                     default property alias cardData: _cardCol.data
                     property alias cardSpacing: _cardCol.spacing
-                    radius: Theme.radius
+                    radius: Theme.radiusCard
                     color: Theme.cardBg
                     implicitHeight: _cardCol.height + 2 * Theme.cardPad
                     Column {
@@ -1110,7 +1121,7 @@ in
                             Rectangle {
                                 width: parent.width
                                 height: launcherList.contentHeight + 2 * Theme.cardPad
-                                radius: Theme.radius
+                                radius: Theme.radiusCard
                                 color: Theme.cardBg
                                 visible: launcherList.count > 0
 
@@ -1173,7 +1184,7 @@ in
                             Rectangle {
                                 width: parent.width
                                 height: 36
-                                radius: Theme.radius
+                                radius: Theme.radiusCard
                                 color: Theme.cardBg
 
                                 SIcon {
@@ -2201,7 +2212,7 @@ in
                         anchors.centerIn: parent
                         width: 48
                         height: sessionCol.height + 8
-                        radius: Theme.radius
+                        radius: Theme.radiusCard
                         color: Theme.cardBg
 
                         // Sliding selection pill — same tech as the power
@@ -2209,7 +2220,7 @@ in
                         Rectangle {
                             width: 40
                             height: 40
-                            radius: Theme.radius
+                            radius: Theme.radiusCard
                             color: Theme.base02
                             border.width: 1
                             border.color: Theme.base03
@@ -2984,7 +2995,7 @@ in
                             Rectangle {
                                 width: parent.width
                                 height: weatherRow.height + 16
-                                radius: Theme.radius
+                                radius: Theme.radiusCard
                                 color: Theme.cardBg
                                 visible: calPopup.weatherDays.length > 0
 
@@ -3046,7 +3057,7 @@ in
                                     property var pwNode: calPopup.streamFor(modelData)
                                     width: parent.width
                                     height: mediaCol.height + 16
-                                    radius: Theme.radius
+                                    radius: Theme.radiusCard
                                     color: Theme.cardBg
 
                                     PwObjectTracker { objects: mediaCard.pwNode ? [mediaCard.pwNode] : [] }
@@ -3497,7 +3508,7 @@ in
                             anchors.margins: Theme.panelGap
                             width: 320 - 2 * Theme.panelGap
                             height: Math.max(toastPreview.visible ? 48 : 0, toastCol.height) + 16
-                            radius: Theme.radius
+                            radius: Theme.radiusCard
                             color: Theme.cardBg
 
                             property string previewSource: bar.notifPreviewSource(toastItem.currentNotif)

settings/ui.nix

@@ -0,0 +1,16 @@
+# settings/ui.nix — shared UI metrics.
+#
+# Single source of truth for corner rounding. Both the quickshell shell
+# (settings/quickshell.nix -> Theme.qml) and hyprland's window decoration
+# (settings/hyprland.nix) read `radius` from here, and every other rounding
+# value is derived from it, so this one number rescales the roundness of the
+# whole desktop — panels, cards, pills, hover rows and window corners.
+#
+# Derived values live next to their consumers:
+#   Theme.radiusCard  = radius - panelGap  (concentric nesting, see Theme.qml)
+#   Theme.radiusSmall = radius * 0.75
+#   Theme.radiusTiny  = radius * 0.5
+#   hyprland decoration.rounding = radius
+{
+  radius = 24;
+}