From d0580d92e8a25878481806ebab2c60e538cbb8f7 Mon Sep 17 00:00:00 2001
From: Nathan Walker <walkerrunpdx@gmail.com>
Date: Fri, 23 Oct 2026 11:43:16 -0700
Subject: [PATCH] fix: substitute Angular 22.1 CSS custom property namespace
 placeholder

Angular 22.1 compiles custom properties in component styles and
[style.--x] bindings to `--%NS%name` / `var(--%NS%name)` and expects the
renderer to replace `%NS%`. The NativeScript renderer passed the
placeholder through, so:

- `var(--x)` in a component never resolved against `--x` declared in
  app.css/app.scss.
- Declaring any custom property in a component stylesheet made the
  NativeScript CSS parser reject `--%NS%x:` and silently drop the whole
  stylesheet.

Strip the placeholder (Angular's default empty namespace) for emulated
and unencapsulated component styles and for setStyle/removeStyle.
---
 .../src/tests/css-variables.spec.ts           | 67 +++++++++++++++++++
 .../angular/src/lib/nativescript-renderer.ts  | 19 +++++-
 2 files changed, 84 insertions(+), 2 deletions(-)
 create mode 100644 apps/nativescript-demo-ng/src/tests/css-variables.spec.ts

diff --git a/apps/nativescript-demo-ng/src/tests/css-variables.spec.ts b/apps/nativescript-demo-ng/src/tests/css-variables.spec.ts
new file mode 100644
index 0000000..5dffb7b
--- /dev/null
+++ b/apps/nativescript-demo-ng/src/tests/css-variables.spec.ts
@@ -0,0 +1,67 @@
+import {
+  Component,
+  ElementRef,
+  inject,
+  NO_ERRORS_SCHEMA,
+  Renderer2,
+  ViewChild,
+  ViewEncapsulation,
+} from '@angular/core';
+import { TestBed } from '@angular/core/testing';
+import { NativeScriptCommonModule } from '@nativescript/angular';
+import { Color, Label } from '@nativescript/core';
+
+// Styles are written in the namespaced form Angular >= 22.1 compiles custom properties to,
+// so these specs hold regardless of the compiler version the demo app builds with.
+
+@Component({
+  template: `<Label #label class="css-var-emulated"></Label>`,
+  styles: ['.css-var-emulated { --%NS%probe-emulated: #ff0000; background-color: var(--%NS%probe-emulated); }'],
+  imports: [NativeScriptCommonModule],
+  schemas: [NO_ERRORS_SCHEMA],
+})
+class EmulatedCssVarComponent {
+  @ViewChild('label', { static: true }) label: ElementRef<Label>;
+  renderer = inject(Renderer2);
+}
+
+@Component({
+  template: `<Label #label class="css-var-none"></Label>`,
+  styles: ['.css-var-none { --%NS%probe-none: #00ff00; background-color: var(--%NS%probe-none); }'],
+  encapsulation: ViewEncapsulation.None,
+  imports: [NativeScriptCommonModule],
+  schemas: [NO_ERRORS_SCHEMA],
+})
+class NoneCssVarComponent {
+  @ViewChild('label', { static: true }) label: ElementRef<Label>;
+}
+
+describe('CSS custom properties', () => {
+  beforeEach(() => TestBed.configureTestingModule({ imports: [EmulatedCssVarComponent, NoneCssVarComponent] }));
+
+  it('applies namespaced custom properties in emulated component styles', () => {
+    const fixture = TestBed.createComponent(EmulatedCssVarComponent);
+    fixture.detectChanges();
+    const label = fixture.componentInstance.label.nativeElement;
+    expect(label.style.getCssVariable('--probe-emulated')).toBe('#ff0000');
+    expect(label.style.backgroundColor?.hex).toBe(new Color('#ff0000').hex);
+  });
+
+  it('applies namespaced custom properties in unencapsulated component styles', () => {
+    const fixture = TestBed.createComponent(NoneCssVarComponent);
+    fixture.detectChanges();
+    const label = fixture.componentInstance.label.nativeElement;
+    expect(label.style.getCssVariable('--probe-none')).toBe('#00ff00');
+    expect(label.style.backgroundColor?.hex).toBe(new Color('#00ff00').hex);
+  });
+
+  it('sets and removes namespaced custom properties through the renderer', () => {
+    const fixture = TestBed.createComponent(EmulatedCssVarComponent);
+    fixture.detectChanges();
+    const { label, renderer } = fixture.componentInstance;
+    renderer.setStyle(label.nativeElement, '--%NS%bound', 'blue');
+    expect(label.nativeElement.style.getCssVariable('--bound')).toBe('blue');
+    renderer.removeStyle(label.nativeElement, '--%NS%bound');
+    expect(label.nativeElement.style.getCssVariable('--bound')).toBeNull();
+  });
+});
diff --git a/packages/angular/src/lib/nativescript-renderer.ts b/packages/angular/src/lib/nativescript-renderer.ts
index 03ef3af..977daec 100644
--- a/packages/angular/src/lib/nativescript-renderer.ts
+++ b/packages/angular/src/lib/nativescript-renderer.ts
@@ -43,6 +43,15 @@ const addStyleToCss = profile(
   },
 );
 
+// Angular >= 22.1 compiles custom properties in component styles and style bindings
+// to `--%NS%name`, leaving the renderer to substitute a namespace. NativeScript has no
+// namespacing, so drop the placeholder to match Angular's default (an empty namespace).
+const CSS_VAR_NAMESPACE_REGEX = /%NS%/g;
+
+function stripCssVarNamespace(input: string): string {
+  return input.replace(CSS_VAR_NAMESPACE_REGEX, '');
+}
+
 function runInRootZone<T>(fn: () => T): T {
   if (typeof Zone === 'undefined') {
     return fn();
@@ -156,7 +165,7 @@ export class NativeScriptRendererFactory implements RendererFactory2 {
     }
 
     if (type.encapsulation === ViewEncapsulation.None) {
-      type.styles.map((s) => s.toString()).forEach((v) => addStyleToCss(v, this.rootModuleID));
+      type.styles.map((s) => stripCssVarNamespace(s.toString())).forEach((v) => addStyleToCss(v, this.rootModuleID));
       renderer = this.defaultRenderer;
     } else {
       runInInjectionContext(this.injector, () => {
@@ -404,6 +413,9 @@ class NativeScriptRenderer implements Renderer2 {
     if (NativeScriptDebug.enabled) {
       NativeScriptDebug.rendererLog(`NativeScriptRenderer.setStyle: ${el}, ${style} = ${value}`);
     }
+    if (style.startsWith('--')) {
+      style = stripCssVarNamespace(style);
+    }
     this.viewUtil.setStyle(el, style, value);
   }
   @inRootZone()
@@ -412,6 +424,9 @@ class NativeScriptRenderer implements Renderer2 {
     if (NativeScriptDebug.enabled) {
       NativeScriptDebug.rendererLog('NativeScriptRenderer.removeStyle: ${styleName}');
     }
+    if (style.startsWith('--')) {
+      style = stripCssVarNamespace(style);
+    }
     this.viewUtil.removeStyle(el, style);
   }
   @inRootZone()
@@ -522,7 +537,7 @@ export class EmulatedRenderer extends NativeScriptRenderer {
   private addStyles(styles: (string | any[])[], componentId: string) {
     styles
       .map((s) => s.toString())
-      .map((s) => replaceNgAttribute(s, componentId))
+      .map((s) => stripCssVarNamespace(replaceNgAttribute(s, componentId)))
       .forEach((s) => addScopedStyleToCss(s, this.rootModuleId));
   }
 }