fix(webgl): release throwaway context in premultiply-alpha probe

src/core/lib/validateImageBitmap.test.ts

@@ -44,6 +44,10 @@ function createFakeGl(readbackRed: number, framebufferComplete = true) {
     ),
     deleteFramebuffer: vi.fn(),
     deleteTexture: vi.fn(),
+    // The probe releases its throwaway context via WEBGL_lose_context once done.
+    getExtension: vi.fn((name: string) =>
+      name === 'WEBGL_lose_context' ? { loseContext: vi.fn() } : null,
+    ),
   };
 }
 
@@ -116,4 +120,15 @@ describe('detectPremultiplyAlphaHonored', () => {
       false,
     );
   });
+
+  it('releases the throwaway context so it does not leak a GL slot', async () => {
+    const lose = { loseContext: vi.fn() };
+    const gl = createFakeGl(128);
+    gl.getExtension = vi.fn((name: string) =>
+      name === 'WEBGL_lose_context' ? lose : null,
+    );
+    await detectPremultiplyAlphaHonored(createPlatform(gl));
+    expect(gl.getExtension).toHaveBeenCalledWith('WEBGL_lose_context');
+    expect(lose.loseContext).toHaveBeenCalledTimes(1);
+  });
 });

src/core/lib/validateImageBitmap.ts

@@ -172,5 +172,13 @@ export async function detectPremultiplyAlphaHonored(
   gl.deleteTexture(tex);
   bitmap.close?.();
 
+  // Release this throwaway context immediately. Embedded TV browsers cap the
+  // number of live WebGL contexts very low; since this probe runs AFTER the
+  // main render context is created, a leaked context here is the newest one
+  // and its lingering presence can push the page over the limit, evicting the
+  // OLDEST context (the live render context) — which then fails every
+  // createTexture. Don't wait for GC to reclaim the canvas; drop it now.
+  gl.getExtension('WEBGL_lose_context')?.loseContext();
+
   return result;
 }