feat(api): add memoir image placeholder parsing

Made-with: Cursor

api/tests/test_memoir_image_parser.py

@@ -0,0 +1,45 @@
+import unittest
+
+from api.services.memoir_images.parser import (
+    build_initial_image_assets,
+    parse_image_placeholders,
+)
+
+
+class MemoirImageParserTest(unittest.TestCase):
+    def test_parse_image_placeholders_preserves_order_and_offsets(self):
+        content = (
+            "那条路我一直记得。\n\n"
+            "{{{{IMAGE:南方小镇的青石板路}}}}\n\n"
+            "奶奶总坐在门口。\n\n"
+            "{{{{IMAGE:奶奶坐在院子里的藤椅上}}}}"
+        )
+
+        items = parse_image_placeholders(content, max_images=3)
+
+        self.assertEqual([item["index"] for item in items], [0, 1])
+        self.assertEqual(items[0]["description"], "南方小镇的青石板路")
+        self.assertEqual(items[1]["placeholder"], "{{{{IMAGE:奶奶坐在院子里的藤椅上}}}}")
+        self.assertLess(items[0]["start_offset"], items[1]["start_offset"])
+
+    def test_build_initial_image_assets_marks_every_item_pending(self):
+        placeholders = [
+            {
+                "index": 0,
+                "description": "南方小镇的青石板路",
+                "placeholder": "{{{{IMAGE:南方小镇的青石板路}}}}",
+                "start_offset": 10,
+            }
+        ]
+
+        assets = build_initial_image_assets(
+            placeholders=placeholders,
+            provider="liblib",
+            style="watercolor",
+            size="1024x1024",
+            now_iso="2026-03-10T10:00:00Z",
+        )
+
+        self.assertEqual(assets[0]["status"], "pending")
+        self.assertEqual(assets[0]["provider"], "liblib")
+        self.assertEqual(assets[0]["url"], None)