Fix memoir image delivery and Android rendering

api/tests/test_memoir_image_bootstrap.py

@@ -66,3 +66,23 @@ class MemoirImageBootstrapTest(unittest.TestCase):
         self.assertEqual(assets[0]["url"], "https://cos.example.com/existing.png")
         self.assertEqual(assets[1]["status"], "pending")
         self.assertEqual(assets[1]["description"], "奶奶坐在院子里的藤椅上")
+
+    def test_initialize_chapter_images_accepts_double_brace_placeholders(self):
+        chapter = type(
+            "ChapterStub",
+            (),
+            {
+                "id": "chapter-1",
+                "title": "童年的夏天",
+                "category": "childhood",
+                "content": "开头。\n\n{{IMAGE:1938年初的上海弄堂口，冬日萧瑟}}\n\n结尾。",
+                "images": [],
+            },
+        )()
+
+        with unittest.mock.patch.dict(os.environ, {"MEMOIR_IMAGE_ENABLED": "true"}, clear=False):
+            assets = initialize_chapter_images(chapter)
+
+        self.assertEqual(len(assets), 1)
+        self.assertEqual(assets[0]["status"], "pending")
+        self.assertEqual(assets[0]["placeholder"], "{{IMAGE:1938年初的上海弄堂口，冬日萧瑟}}")