refactor(widget): decouple from gg/scene with SceneCache interface (ADR-036)

CHANGELOG.md

@@ -5,6 +5,20 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Changed
+
+- **refactor(widget): decouple widget/ from gg/scene** (ADR-036 Phase 1) — replaced `*scene.Scene` with `SceneCache` interface in widget package. Third-party widget authors importing `widget/` + `geometry/` + `event/` now compile **71 packages instead of 124** (zero gg/wgpu/naga in the dependency chain). `SceneFactory` registration pattern follows existing `SceneRecorder` DI.
+  - New: `widget.SceneCache` interface (`Reset()`, `IsEmpty()`), `widget.SceneFactory`, `widget.RegisterSceneFactory()`, `widget.NewSceneCache()`
+  - Changed: `Canvas.ReplayScene(*scene.Scene)` → `Canvas.ReplayScene(SceneCache)`
+  - Changed: `WidgetBase.CachedScene()` / `SetCachedScene()` types → `SceneCache`
+  - Changed: `SceneRecorder` function signature uses `SceneCache`
+  - 92 files changed, rendering layer uses type assertions where concrete `*scene.Scene` needed
+- **deps:** gg v0.50.11 → v0.50.12, gogpu v0.48.5 → v0.50.0, wgpu v0.30.35 → v0.30.36
+  - **gogpu v0.50.0:** outgoing drag-and-drop, per-pixel-alpha transparency, window Show/Hide/SetPosition/SetSize API, macOS menu Role+Action fix.
+  - **wgpu v0.30.36:** Vulkan present semaphore fix.
+
 ## [0.1.50] — 2026-08-03
 
 ### Fixed

app/boundary_visibility_test.go

@@ -133,8 +133,8 @@ func TestIsBoundaryVisible_AboveClip_Invisible(t *testing.T) {
 func setupSceneRecorder(t *testing.T) func() {
 	t.Helper()
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	return func() { widget.RegisterSceneRecorder(prev) }

app/compositor_test.go

@@ -189,8 +189,8 @@ func (w *containerTestWidget) Draw(_ widget.Context, canvas widget.Canvas) {
 func (w *containerTestWidget) Event(_ widget.Context, _ event.Event) bool { return false }
 func (w *containerTestWidget) Children() []widget.Widget                  { return w.children }
 
-// testSceneRecorder creates a SceneCanvas for recording into scene.Scene.
-func testSceneRecorder(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-	rec := internalRender.NewSceneCanvas(s, w, h)
+// testSceneRecorder creates a SceneCanvas for recording into SceneCache.
+func testSceneRecorder(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+	rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 	return rec, rec.Close
 }

app/drawchild_skip_test.go

@@ -62,8 +62,8 @@ func (w *itemWidget) Children() []widget.Widget                  { return nil }
 func TestDrawChildSkip_ListViewItemBoundaries(t *testing.T) {
 	// Register SceneRecorder factory (required for boundary recording).
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -154,7 +154,7 @@ func TestDrawChildSkip_ListViewItemBoundaries(t *testing.T) {
 		t.Logf("item[%d]: bounds=%v (%.0fx%.0f)", i, bounds, bounds.Width(), bounds.Height())
 
 		// 5c: Item has cached scene (recorded by PaintBoundaryLayers recursion).
-		sc, ok := item.(interface{ CachedScene() *scene.Scene })
+		sc, ok := item.(interface{ CachedScene() widget.SceneCache })
 		if !ok {
 			t.Errorf("item[%d]: does not implement CachedScene()", i)
 			continue
@@ -187,8 +187,8 @@ func TestDrawChildSkip_ListViewItemBoundaries(t *testing.T) {
 // Items should NOT appear in the root's scene -- they have their own scenes.
 func TestDrawChildSkip_RootRecordingSkipsItems(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -239,7 +239,7 @@ func TestDrawChildSkip_RootRecordingSkipsItems(t *testing.T) {
 	// After PaintBoundaryLayers, item boundaries should also have scenes.
 	items := collectBoundaryDescendants(root)
 	for i, item := range items {
-		if sc, ok := item.(interface{ CachedScene() *scene.Scene }); ok {
+		if sc, ok := item.(interface{ CachedScene() widget.SceneCache }); ok {
 			cs := sc.CachedScene()
 			if cs == nil {
 				t.Errorf("item[%d]: CachedScene nil after PaintBoundaryLayers", i)
@@ -255,8 +255,8 @@ func TestDrawChildSkip_RootRecordingSkipsItems(t *testing.T) {
 // though they were created dynamically during VirtualContent.Draw().
 func TestDrawChildSkip_ItemsExistAfterRootRecording(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -324,8 +324,8 @@ func TestDrawChildSkip_ItemsExistAfterRootRecording(t *testing.T) {
 // both the Box background and the Text content.
 func TestDrawChildSkip_BoxTextItems_ProductionScenario(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -379,7 +379,7 @@ func TestDrawChildSkip_BoxTextItems_ProductionScenario(t *testing.T) {
 	}
 
 	for i, item := range items {
-		sc, ok := item.(interface{ CachedScene() *scene.Scene })
+		sc, ok := item.(interface{ CachedScene() widget.SceneCache })
 		if !ok {
 			t.Errorf("item[%d]: does not implement CachedScene()", i)
 			continue
@@ -505,7 +505,7 @@ func walkTreeDiag(t *testing.T, w widget.Widget, depth int) {
 	if sd, ok := w.(interface{ IsSceneDirty() bool }); ok {
 		sceneDirty = sd.IsSceneDirty()
 	}
-	if sc, ok := w.(interface{ CachedScene() *scene.Scene }); ok {
+	if sc, ok := w.(interface{ CachedScene() widget.SceneCache }); ok {
 		hasScene = sc.CachedScene() != nil
 	}
 

app/first_frame_test.go

@@ -65,7 +65,7 @@ func (c *trackingCanvas) PopTransform()                                {}
 func (c *trackingCanvas) TransformOffset() geometry.Point              { return geometry.Point{} }
 func (c *trackingCanvas) ScreenOriginBase() geometry.Point             { return geometry.Point{} }
 func (c *trackingCanvas) ClipBounds() geometry.Rect                    { return geometry.NewRect(0, 0, 10000, 10000) }
-func (c *trackingCanvas) ReplayScene(_ *scene.Scene)                   {}
+func (c *trackingCanvas) ReplayScene(_ widget.SceneCache)              {}
 
 // Compile-time check.
 var _ widget.Canvas = (*trackingCanvas)(nil)

app/hover_boundary_e2e_test.go

@@ -23,8 +23,8 @@ import (
 func TestHoverE2E_ButtonInBoundary_DirtyPropagation(t *testing.T) {
 	// Register SceneRecorder factory for boundary recording.
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -124,8 +124,8 @@ func TestHoverE2E_ButtonInBoundary_DirtyPropagation(t *testing.T) {
 // multiple levels of nesting. Button inside Box inside Box inside root boundary.
 func TestHoverE2E_DeepNesting_PropagatesUpward(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -205,8 +205,8 @@ func TestHoverE2E_DeepNesting_PropagatesUpward(t *testing.T) {
 // Window.HandleEvent → updateHover → hitTest → MouseEnter → dirty propagation.
 func TestHoverE2E_WindowHandleEvent_FullChain(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)

app/layer_tree.go

@@ -1,7 +1,6 @@
 package app
 
 import (
-	"github.com/gogpu/gg/scene"
 	"github.com/gogpu/gpucontext"
 	"github.com/gogpu/ui/compositor"
 	"github.com/gogpu/ui/geometry"
@@ -31,8 +30,8 @@ type boundaryInfo interface {
 	widget.Widget
 	IsRepaintBoundary() bool
 	IsSceneDirty() bool
-	CachedScene() *scene.Scene
-	SetCachedScene(*scene.Scene)
+	CachedScene() widget.SceneCache
+	SetCachedScene(widget.SceneCache)
 	ClearSceneDirty()
 	SceneCacheSize() (int, int)
 	SetSceneCacheSize(int, int)
@@ -519,7 +518,7 @@ func recordBoundary(bi boundaryInfo, ctx widget.Context) {
 
 	cachedScene := bi.CachedScene()
 	if cachedScene == nil {
-		cachedScene = scene.NewScene()
+		cachedScene = widget.NewSceneCache()
 	}
 	cachedScene.Reset()
 

app/overlay_damage_tracking_test.go

@@ -43,8 +43,8 @@ func TestOverlayBoundary_SceneDirtyAfterHover(t *testing.T) {
 
 	// Record initial scene to clear dirty state.
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -94,8 +94,8 @@ func TestOverlayBoundary_RecordClearsButVersionIncrements(t *testing.T) {
 	menu.SetScreenOrigin(geometry.Pt(100, 200))
 
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -140,8 +140,8 @@ func TestOverlayBoundary_SyncPictureLayerDetectsVersionChange(t *testing.T) {
 	menu.SetScreenOrigin(geometry.Pt(100, 200))
 
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -201,8 +201,8 @@ func TestOverlayBoundary_SyncPictureLayerDetectsVersionChange(t *testing.T) {
 // should still trigger re-render.
 func TestOverlayBoundary_FullPipeline_HoverGeneratesDamage(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -339,8 +339,8 @@ func TestOverlayBoundary_FullPipeline_HoverGeneratesDamage(t *testing.T) {
 // version does not change, and the PictureLayer stays clean.
 func TestOverlayBoundary_CleanHover_NoRender(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -396,8 +396,8 @@ func TestOverlayBoundary_StandalonePropagation(t *testing.T) {
 	menu.SetScreenOrigin(geometry.Pt(100, 200))
 
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)
@@ -434,8 +434,8 @@ func TestOverlayBoundary_OnBoundaryDirtyCallback(t *testing.T) {
 	menu.SetScreenOrigin(geometry.Pt(100, 200))
 
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)

app/scene_recorder.go

@@ -7,13 +7,19 @@ import (
 )
 
 func init() {
+	// Register the SceneFactory so that widget.DrawTree can create new
+	// SceneCache instances for WidgetBase-based repaint boundaries (ADR-024).
+	widget.RegisterSceneFactory(func() widget.SceneCache {
+		return scene.NewScene()
+	})
+
 	// Register the SceneRecorder factory so that widget.DrawTree can create
 	// recording canvases for WidgetBase-based repaint boundaries (ADR-024).
 	//
 	// The widget package cannot import internal/render (circular dep), so
 	// we inject the factory here during package initialization.
-	widget.RegisterSceneRecorder(func(s *scene.Scene, width, height int) (widget.Canvas, func()) {
-		recorder := internalRender.NewSceneCanvas(s, width, height)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, width, height int) (widget.Canvas, func()) {
+		recorder := internalRender.NewSceneCanvas(s.(*scene.Scene), width, height)
 		return recorder, recorder.Close
 	})
 }

app/screen_origin_test.go

@@ -141,7 +141,7 @@ func (w *screenOriginLeaf) Children() []widget.Widget                  { return
 
 // testSceneRecorder is defined in compositor_test.go but redeclared here
 // for this test file. Uses the same pattern.
-func testSceneRecorderForOriginTests(s *scene.Scene, w, h int) (widget.Canvas, func()) { //nolint:unused // retained for future screen origin test variants
-	rec := internalRender.NewSceneCanvas(s, w, h)
+func testSceneRecorderForOriginTests(s widget.SceneCache, w, h int) (widget.Canvas, func()) { //nolint:unused // retained for future screen origin test variants
+	rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 	return rec, rec.Close
 }

app/spinner_e2e_test.go

@@ -37,8 +37,8 @@ func (w *boxContainer) Children() []widget.Widget                  { return w.ki
 // Verifies spinner is found by PaintBoundaryLayers AND visible in composed scene.
 func TestSpinnerE2E_VisibleInCompositor(t *testing.T) {
 	prev := widget.GetSceneRecorderFactory()
-	widget.RegisterSceneRecorder(func(s *scene.Scene, w, h int) (widget.Canvas, func()) {
-		rec := internalRender.NewSceneCanvas(s, w, h)
+	widget.RegisterSceneRecorder(func(s widget.SceneCache, w, h int) (widget.Canvas, func()) {
+		rec := internalRender.NewSceneCanvas(s.(*scene.Scene), w, h)
 		return rec, rec.Close
 	})
 	defer widget.RegisterSceneRecorder(prev)

app/window_draw_test.go

@@ -1,7 +1,6 @@
 package app
 
 import (
-	"github.com/gogpu/gg/scene"
 	"image"
 	"testing"
 
@@ -49,7 +48,7 @@ func (c *recordingCanvas) PopTransform()                                {}
 func (c *recordingCanvas) TransformOffset() geometry.Point              { return geometry.Point{} }
 func (c *recordingCanvas) ScreenOriginBase() geometry.Point             { return geometry.Point{} }
 func (c *recordingCanvas) ClipBounds() geometry.Rect                    { return geometry.NewRect(0, 0, 10000, 10000) }
-func (c *recordingCanvas) ReplayScene(_ *scene.Scene)                   {}
+func (c *recordingCanvas) ReplayScene(_ widget.SceneCache)              {}
 
 // drawTrackingWidget tracks whether Draw was called and has configurable bounds.
 type drawTrackingWidget struct {

app/window_test.go

@@ -1,7 +1,6 @@
 package app
 
 import (
-	"github.com/gogpu/gg/scene"
 	"image"
 	"testing"
 
@@ -458,7 +457,7 @@ func (m *mockCanvas) PopTransform()                                {}
 func (m *mockCanvas) TransformOffset() geometry.Point              { return geometry.Point{} }
 func (m *mockCanvas) ScreenOriginBase() geometry.Point             { return geometry.Point{} }
 func (m *mockCanvas) ClipBounds() geometry.Rect                    { return geometry.NewRect(0, 0, 10000, 10000) }
-func (m *mockCanvas) ReplayScene(_ *scene.Scene)                   {}
+func (m *mockCanvas) ReplayScene(_ widget.SceneCache)              {}
 
 // --- Retained-mode rendering tests ---
 

compositor/compositor.go

@@ -53,8 +53,10 @@ func (c *Compositor) composeLayer(layer Layer, parentX, parentY float32) {
 	// PictureLayer: append its scene at accumulated offset.
 	if po, ok := layer.(PictureOwner); ok {
 		pic := po.Picture()
-		if pic != nil && !pic.IsEmpty() {
-			c.composed.AppendWithTranslation(pic, x, y)
+		if pic != nil {
+			if sc, ok2 := pic.(*scene.Scene); ok2 && !sc.IsEmpty() {
+				c.composed.AppendWithTranslation(sc, x, y)
+			}
 		}
 		layer.ClearNeedsCompositing()
 		return