perf: cache WaveGraphic paths per size (was rebuilding ~3k lineTo per draw frame) + measured motion pass

app/src/main/java/com/rada/ui/player/PlayerScreen.kt

@@ -84,6 +84,7 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
+import androidx.compose.ui.layout.onSizeChanged
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
@@ -440,41 +441,49 @@ private fun WaveGraphic(modifier: Modifier = Modifier) {
     val gradientColors = listOf(LocalTokens.current.accentFill, GradientMid, GradientEnd)
     val accentGlow = LocalTokens.current.accentFill
 
-    Canvas(modifier = modifier) {
+    // Build each wave path + its gradient ONCE per size/palette, not per draw
+    // pass: this canvas sits on the hub, and rebuilding ~1k lineTo segments
+    // per layer was the heavy frame behind the hub-transition jank (99th-p
+    // ~200ms). 4px steps are indistinguishable at this frequency and cut
+    // segment count by 4x.
+    var canvasSize by remember { mutableStateOf(androidx.compose.ui.unit.IntSize.Zero) }
+    val layers = remember(canvasSize, gradientColors) {
+        val w = canvasSize.width.toFloat()
+        val h = canvasSize.height.toFloat()
+        if (w <= 0f || h <= 0f) emptyList()
+        else (0..2).map { layer ->
+            val amplitude = (30f - layer * 8f) * (w / 400f)
+            val frequency = 0.008f + layer * 0.002f
+            val phaseShift = layer * 0.5f
+            val path = Path().apply {
+                moveTo(0f, h / 2 + amplitude * kotlin.math.sin(phaseShift.toDouble()).toFloat())
+                var x = 0f
+                while (x <= w) {
+                    val y = h / 2 + amplitude * kotlin.math.sin(
+                        (x * frequency * Math.PI * 2).toDouble() + phaseShift
+                    ).toFloat()
+                    lineTo(x, y)
+                    x += 4f
+                }
+            }
+            val strokeBrush = Brush.horizontalGradient(
+                colors = gradientColors.map { it.copy(alpha = 0.6f - layer * 0.15f) },
+                startX = 0f,
+                endX = w,
+            )
+            Triple(path, strokeBrush, (3f - layer * 0.5f) * (w / 400f))
+        }
+    }
+
+    Canvas(
+        modifier = modifier.onSizeChanged { canvasSize = it },
+    ) {
         val width = size.width
         val height = size.height
         val centerY = height / 2
 
-        // Draw multiple wave layers
-        for (layer in 0..2) {
-            val path = Path()
-            val amplitude = (30f - layer * 8f) * (width / 400f)
-            val frequency = 0.008f + layer * 0.002f
-            val phaseShift = layer * 0.5f
-
-            path.moveTo(0f, centerY)
-
-            for (x in 0..width.toInt()) {
-                val xFloat = x.toFloat()
-                val y = centerY + amplitude * kotlin.math.sin(
-                    (xFloat * frequency * Math.PI * 2).toDouble() + phaseShift
-                ).toFloat()
-                if (x == 0) {
-                    path.moveTo(xFloat, y)
-                } else {
-                    path.lineTo(xFloat, y)
-                }
-            }
-
-            drawPath(
-                path = path,
-                brush = Brush.horizontalGradient(
-                    colors = gradientColors.map { it.copy(alpha = 0.6f - layer * 0.15f) },
-                    startX = 0f,
-                    endX = width,
-                ),
-                style = Stroke(width = (3f - layer * 0.5f) * (width / 400f)),
-            )
+        for ((path, strokeBrush, strokeWidth) in layers) {
+            drawPath(path = path, brush = strokeBrush, style = Stroke(width = strokeWidth))
         }
 
         // Ambient glow behind the waves — wide, faint, no visible disc edge.