fix(transform): isolate nested preview siblings (#7280)

crates/ui-egui/src/transform_tool.rs

@@ -792,13 +792,11 @@ fn preview_image(
         (None, Some(s)) if layer.is_some_and(|l| matches!(l.content, LayerContent::Raster(_))) => Some(s),
         _ => {
             let mut solo = doc.clone();
-            for l in solo.layers.iter_mut() {
-                if l.id != id && doc.layer(id).is_some_and(|_| !contains(l, id)) {
-                    l.visible = false;
-                } else {
-                    // Its clipping base is hidden here, which would clip it away entirely (#5239).
-                    l.clipped = false;
-                }
+            show_only(&mut solo.layers, &[id]);
+            // Its clipping base is hidden here, which would clip it away entirely (#5239).
+            // Clear the target itself, not only the top-level group that contains it.
+            if let Some(l) = solo.layer_mut(id) {
+                l.clipped = false;
             }
             if let Some(l) = solo.layer_mut(id).filter(|_| bare) {
                 l.effects.enabled = false;
@@ -4747,6 +4745,29 @@ mod tests {
         assert!(pv.texture.size()[0] as f64 >= t.rect[2] - t.rect[0]);
     }
 
+    #[test]
+    fn nested_group_preview_excludes_its_siblings() {
+        use photocraft_color::PixelFormat;
+        use photocraft_doc::Layer;
+
+        let mut app = app_with_square(64, photocraft_geom::Rect::new(8, 8, 24, 24));
+        let st = app.session.active_mut().unwrap();
+        let doc = Arc::make_mut(&mut st.doc);
+        let target_pixels = doc.layers.pop().unwrap();
+        let mut sibling = Layer::raster("sibling", PixelFormat::RGBA8);
+        sibling.surface_mut().unwrap().fill_rect(photocraft_geom::Rect::new(12, 12, 20, 20), &[0.0, 0.0, 1.0, 1.0]);
+        let target = Layer::group("target", vec![target_pixels]);
+        let target_id = target.id;
+        doc.layers.push(Layer::group("parent", vec![target, sibling]));
+
+        let (image, _) = preview_image(&st.doc, target_id, None, photocraft_geom::Rect::new(8, 8, 24, 24), 4096, false);
+        assert_eq!(
+            image.pixels[8 * image.size[0] + 8],
+            Color32::from_rgb(255, 0, 0),
+            "a sibling in the parent group must not be baked into the moving texture"
+        );
+    }
+
     /// The textured meshes `draw_content` paints for the moving pixels (not the box or handles).
     fn preview_meshes(app: &PhotocraftApp, xf: &ViewXform) -> Vec<egui::Mesh> {
         let ctx = gpu_ctx();