fix(observation): restore body updates for observable state

Example/OpenSwiftUIUXTests/Data/Observation/ObservationUXTests.swift

@@ -0,0 +1,52 @@
+//
+//  ObservationUXTests.swift
+//  OpenSwiftUIUXTests
+
+#if OPENSWIFTUI
+import OpenObservation
+import OpenSwiftUI
+#else
+import Observation
+import SwiftUI
+#endif
+import Testing
+
+@MainActor
+@Suite
+struct ObservationUXTests {
+    @Test
+    func stateModelMutationUpdatesBody() async throws {
+        var displayedCounts: [Int] = []
+        let content = CounterView { displayedCounts.append($0) }
+
+        try await withUXTestHost(of: content) { host in
+            try await host.waitUntil(displayedCounts == [0])
+            for count in 1...2 {
+                try await host.tap()
+                try await host.waitUntil(displayedCounts.last == count)
+                #expect(displayedCounts == Array(0...count))
+            }
+        }
+    }
+}
+
+@Observable
+private final class CounterModel {
+    var count = 0
+}
+
+private struct CounterView: View {
+    @State private var model = CounterModel()
+    let onChange: (Int) -> Void
+
+    var body: some View {
+        let count = model.count
+        Text("\(count)")
+            .onTapGesture {
+                model.count += 1
+            }
+            .onChange(of: count, initial: true) { _, newValue in
+                onChange(newValue)
+            }
+    }
+}

Example/Project.swift

@@ -365,6 +365,7 @@ let targets: [Target] = [
         dependencies: [
             .target(name: "TestingHost"),
             .external(name: "Hammer"),
+            .external(name: "OpenSwiftUITestsSupport"),
         ] + privateFrameworkDependencies,
         settings: settings(base: uxTestsSettings, xcconfig: "../Configurations/OpenSwiftUIUXTests.xcconfig")
     ),

Example/Shared/Data/ObservationExample.swift

@@ -10,31 +10,55 @@ import Observation
 import SwiftUI
 #endif
 
+struct ObservationExample: View {
+    var body: some View {
+        VStack {
+            ObservationColorExample()
+            Divider()
+            ObservationCounterExample()
+        }
+    }
+}
+
 @Observable
-private class Model {
+private class ColorModel {
     var showRed = false
 }
 
-struct ObservationExample: View {
-    @State private var model = Model()
-
-    private var showRed: Bool {
-        get { model.showRed }
-        nonmutating set { model.showRed = newValue }
-    }
+struct ObservationColorExample: View {
+    @State private var model = ColorModel()
 
     var body: some View {
         VStack {
-            Color(platformColor: showRed ? .red : .blue)
-                .frame(width: showRed ? 200 : 400, height: showRed ? 200 : 400)
-        }
-        .animation(.spring, value: showRed)
-        .onTapGesture {
-            showRed.toggle()
+            Color(model.showRed ? .red : .blue)
+            Text("Toggle")
+                .onTapGesture {
+                    model.showRed.toggle()
+                }
         }
     }
 }
 
 #Preview {
-    ObservationExample()
+    ObservationColorExample()
+}
+
+@Observable
+private final class CounterModel {
+    var count = 0
+}
+
+struct ObservationCounterExample: View {
+    @State private var model = CounterModel()
+
+    var body: some View {
+        Text("Tap to increase: \(model.count)")
+            .onTapGesture {
+                model.count += 1
+            }
+    }
+}
+
+#Preview {
+    ObservationCounterExample()
 }

Example/Tuist/Package.swift

@@ -93,10 +93,11 @@ var packageProductTypes: [String: ProjectDescription.Product] = [
     "OpenSwiftUITestsSupport": ProjectDescription.Product.staticFramework,
     "OpenSwiftUISymbolDualTestsSupport": ProjectDescription.Product.staticFramework,
     "OpenAttributeGraphShims": ProjectDescription.Product.staticFramework,
-    "OpenCoreGraphicsShims": ProjectDescription.Product.staticFramework,
-    "OpenObservation": ProjectDescription.Product.staticFramework,
-    "OpenQuartzCoreShims": ProjectDescription.Product.staticFramework,
-    "OpenRenderBoxShims": ProjectDescription.Product.staticFramework,
+    "OpenCoreGraphicsShims": ProjectDescription.Product.framework,
+    "OpenObservation": ProjectDescription.Product.framework,
+    "OpenObservationCxx": ProjectDescription.Product.staticFramework,
+    "OpenQuartzCoreShims": ProjectDescription.Product.framework,
+    "OpenRenderBoxShims": ProjectDescription.Product.framework,
     "SymbolLocator": ProjectDescription.Product.staticFramework,
 ]
 
@@ -146,6 +147,12 @@ let packageSettings = PackageSettings(
             defaultSettings: .essential,
             defaultConfiguration: "OpenSwiftUIDebug"
         ),
+        "OpenSwiftUITestsSupport": .settings(
+            base: ["ENABLE_TESTING_SEARCH_PATHS": "YES"],
+            configurations: openSwiftUIPackageConfigurations,
+            defaultSettings: .essential,
+            defaultConfiguration: "OpenSwiftUIDebug"
+        ),
         "OpenSwiftUI": .settings(
             base: openSwiftUITargetSettings,
             configurations: openSwiftUIPackageConfigurations,

Sources/OpenSwiftUICore/Data/Observation/ObservationUtils.swift

@@ -140,7 +140,7 @@ private func installObservationSlow<T>(
     accessList: ObservationTracking._AccessList,
     attribute: Attribute<T>
 ) {
-    guard let subgraph = attribute.identifier.subgraph2 else {
+    guard let subgraph = attribute.identifier.subgraphOrNil else {
         return
     }
     let weakViewGraph = WeakUncheckedSendable(ViewGraph.current)