fix: add encoding="utf-8" to paper_storage.py meta.json reads

backend/app/storage/paper_storage.py

@@ -97,7 +97,7 @@ def get_paper(paper_id: str) -> Optional[Dict[str, Any]]:
     path = os.path.join(PAPERS_DIR, paper_id, "meta.json")
     if not os.path.isfile(path):
         return None
-    with open(path) as f:
+    with open(path, encoding="utf-8") as f:
         return _normalize_record(json.load(f))
 
 
@@ -109,7 +109,7 @@ def list_papers() -> List[Dict[str, Any]]:
         meta = os.path.join(PAPERS_DIR, name, "meta.json")
         if os.path.isfile(meta):
             try:
-                with open(meta) as f:
+                with open(meta, encoding="utf-8") as f:
                     results.append(_normalize_record(json.load(f)))
             except Exception:
                 pass

backend/tests/test_pr_03_paper_storage_encoding.py

@@ -0,0 +1,51 @@
+"""Test that paper_storage.py get_paper/list_papers handle non-ASCII content."""
+
+import json
+import os
+from unittest import mock
+
+import pytest
+
+
+@pytest.fixture
+def tmp_papers_dir(tmp_path):
+    d = tmp_path / "papers"
+    d.mkdir()
+    return str(d)
+
+
+def test_get_paper_non_ascii(tmp_papers_dir):
+    """Create a paper with Chinese title/authors and verify get_paper returns it intact."""
+    with mock.patch("app.storage.paper_storage.PAPERS_DIR", tmp_papers_dir):
+        from app.storage import paper_storage
+
+        data = {
+            "title": "基于深度学习的自然语言处理综述",
+            "authors": ["张三", "李四"],
+            "paperType": "survey",
+            "targetVenue": "ACL",
+        }
+        record = paper_storage.create_paper(data)
+        paper_id = record["id"]
+
+        fetched = paper_storage.get_paper(paper_id)
+        assert fetched is not None
+        assert fetched["title"] == "基于深度学习的自然语言处理综述"
+        assert fetched["authors"] == ["张三", "李四"]
+
+
+def test_list_papers_non_ascii(tmp_papers_dir):
+    """Verify list_papers returns non-ASCII titles correctly."""
+    with mock.patch("app.storage.paper_storage.PAPERS_DIR", tmp_papers_dir):
+        from app.storage import paper_storage
+
+        paper_storage.create_paper({"title": "Premier article"})
+        paper_storage.create_paper({"title": "第二篇论文"})
+        paper_storage.create_paper({"title": "Übung macht den Meister"})
+
+        papers = paper_storage.list_papers()
+        assert len(papers) == 3
+        titles = {p["title"] for p in papers}
+        assert "Premier article" in titles
+        assert "第二篇论文" in titles
+        assert "Übung macht den Meister" in titles