Fix sheets ignoring their detents

AndroidSwiftUICore/Tests/AndroidSwiftUICoreTests/NavigationTests.swift

@@ -226,6 +226,34 @@ struct NavigationTests {
         #expect(host.callbacks.callback(for: tap) != nil)
     }
 
+    @Test("A sheet carries its detents, and none by default")
+    func sheetDetents() {
+        struct Screen: View {
+            @State var shown = true
+            var body: some View {
+                Button("Show") { shown = true }
+                    .sheet(isPresented: $shown) {
+                        Text("body").presentationDetents([.medium])
+                    }
+            }
+        }
+        let node = ViewHost(Screen()).evaluate()
+        let sheet = node.children.first { $0.type == "Sheet" }
+        #expect(sheet?.props["detents"] == .array([.string("medium")]))
+
+        // no detents declared: the interpreter reads that as a full-height sheet
+        struct Plain: View {
+            @State var shown = true
+            var body: some View {
+                Button("Show") { shown = true }
+                    .sheet(isPresented: $shown) { Text("body") }
+            }
+        }
+        let plain = ViewHost(Plain()).evaluate()
+        let plainSheet = plain.children.first { $0.type == "Sheet" }
+        #expect(plainSheet?.props["detents"] == .array([]))
+    }
+
     @Test("TabView emits tabs with their item labels and selection")
     func tabs() {
         struct Screen: View {

Demo/swiftui/src/commonMain/kotlin/com/pureswift/swiftui/Render.kt

@@ -90,6 +90,7 @@ import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.ModalBottomSheet
+import androidx.compose.material3.rememberModalBottomSheetState
 import androidx.compose.material3.NavigationBar
 import androidx.compose.material3.pulltorefresh.PullToRefreshBox
 import androidx.compose.material3.NavigationBarItem
@@ -1719,8 +1720,25 @@ private fun RenderSheetsAndAlerts(screen: ViewNode?) {
         when (child.type) {
             "Sheet" -> {
                 val onDismiss = child.long("onDismiss")
-                ModalBottomSheet(onDismissRequest = { onDismiss?.let { SwiftBridge.sink.invokeVoid(it) } }) {
-                    child.children.firstOrNull()?.let { Render(it) }
+                // Detents were emitted but never read, so every sheet wrapped its
+                // content and a "full-size" sheet came up as a short strip.
+                val detents = child.stringArray("detents")
+                val medium = detents.contains("medium")
+                val large = detents.isEmpty() || detents.contains("large")
+                ModalBottomSheet(
+                    onDismissRequest = { onDismiss?.let { SwiftBridge.sink.invokeVoid(it) } },
+                    // with no medium detent there is no partial stop to rest at
+                    sheetState = rememberModalBottomSheetState(skipPartiallyExpanded = !medium),
+                ) {
+                    // A Material sheet is only as tall as its content, so one that
+                    // should own the screen has to be told to fill it.
+                    val height = when {
+                        medium && !large -> Modifier.fillMaxHeight(0.5f)
+                        else -> Modifier.fillMaxHeight()
+                    }
+                    Box(modifier = height) {
+                        child.children.firstOrNull()?.let { Render(it) }
+                    }
                 }
             }
             "Alert" -> RenderAlert(child)