Give Sound the whole story, and keep the buttons inside the card

Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8

config/dot/quickshell/audio-streams-harness.qml

@@ -75,6 +75,21 @@ ShellRoot {
         return AudioStreams.group(fixtureNodes, audioOutStreamFlag);
     }
 
+    // A throwaway two-stream group for the clamp cases. The shared fixture
+    // above is mutated by the volume and mute tests, and a clamp assertion that
+    // depended on which of those ran first would be worthless.
+    function clampFixture(): var {
+        return {
+            key: "clamp",
+            label: "Clamp",
+            icon: "audio-x-generic-symbolic",
+            nodes: [
+                { audio: { volume: 0.1, muted: true } },
+                { audio: { volume: 0.1, muted: true } }
+            ]
+        };
+    }
+
     IpcHandler {
         target: "application-volume-test"
 
@@ -115,6 +130,31 @@ ShellRoot {
             });
         }
 
+        // Over-amplification is a preference, so the ceiling is an argument
+        // rather than a constant -- this file stays Settings-free on purpose.
+        function clampVolume(): string {
+            const overAmp = clampFixture();
+            const overAmpChanged = AudioStreams.setVolume(overAmp, 1.4, 1.5);
+            const ceiling = clampFixture();
+            AudioStreams.setVolume(ceiling, 2.5, 1.5);
+            const defaultMax = clampFixture();
+            AudioStreams.setVolume(defaultMax, 1.4);
+            const floor = clampFixture();
+            AudioStreams.setVolume(floor, -0.5, 1.5);
+            const nonNumeric = clampFixture();
+            const nonNumericChanged = AudioStreams.setVolume(nonNumeric, "loud", 1.5);
+            return JSON.stringify({
+                overAmpChanged,
+                overAmp: overAmp.nodes.map(node => node.audio.volume),
+                overAmpMuted: overAmp.nodes.map(node => node.audio.muted),
+                ceiling: ceiling.nodes.map(node => node.audio.volume),
+                defaultMax: defaultMax.nodes.map(node => node.audio.volume),
+                floor: floor.nodes.map(node => node.audio.volume),
+                nonNumericChanged,
+                nonNumeric: nonNumeric.nodes.map(node => node.audio.volume)
+            });
+        }
+
         function serviceSummary(): string {
             const applications = AudioDevices.applications;
             return JSON.stringify({