Add cloud sprite providers and browser demos

test_server.py

@@ -152,6 +152,17 @@ class TestEnsureDir:
         server._ensure_dir("test.png")
 
 
+class TestPngMetadata:
+    def test_save_sprite_embeds_prompt_and_provenance(self, tmp_path):
+        path = tmp_path / "sprite.png"
+        image = Image.new("RGBA", (4, 4), (1, 2, 3, 255))
+        server._save_sprite(image, str(path), "blue scout", {"provider": "test"})
+
+        with Image.open(path) as saved:
+            assert saved.text["prompt"] == "blue scout"
+            assert '"provider": "test"' in saved.text["imagen"]
+
+
 class TestEnvPaths:
     def test_default_model_dir(self):
         assert "models" in server.MODEL_DIR