diff --git a/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/markdown_storage.py b/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/markdown_storage.py
index 443ef9e3fb..07ff73810b 100644
--- a/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/markdown_storage.py
+++ b/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/markdown_storage.py
@@ -53,7 +53,9 @@ class MarkdownMemoryStorage(FileMemoryStorage):
         if not path.exists():
             return None
         try:
-            raw = path.read_text(encoding="utf-8")
+            # utf-8-sig, matching the base loader: a BOM does not make the
+            # summary unreadable, so it must not trigger the quarantine path.
+            raw = path.read_text(encoding="utf-8-sig")
         except (OSError, UnicodeError) as exc:
             logger.warning("Cannot read memory summary %s: %s", path, exc)
             return None
diff --git a/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py b/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py
index aae958b3ad..9f01eeef71 100644
--- a/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py
+++ b/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py
@@ -1143,7 +1143,11 @@ class FileMemoryStorage(MemoryStorage):
         if not path.exists():
             return None
         try:
-            value = json.loads(path.read_text(encoding="utf-8"))
+            # utf-8-sig: a summary hand-edited on Windows may carry a BOM. The
+            # payload is still valid JSON, so raising MemoryStorageCorruption
+            # here would brick the backend (and the opt-in Markdown loader
+            # would quarantine recoverable state) over an encoding artifact.
+            value = json.loads(path.read_text(encoding="utf-8-sig"))
         except (json.JSONDecodeError, OSError, UnicodeError) as exc:
             raise MemoryStorageCorruption(f"Failed to load global memory JSON {path}: {exc}") from exc
         if not isinstance(value, dict):
diff --git a/backend/tests/test_memory_storage.py b/backend/tests/test_memory_storage.py
index 6b534329de..3d81057a5e 100644
--- a/backend/tests/test_memory_storage.py
+++ b/backend/tests/test_memory_storage.py
@@ -117,6 +117,31 @@ class TestFileMemoryStorage:
         assert isinstance(memory, dict)
         assert memory["version"] == "1.0"
 
+    def test_summary_saved_with_utf8_bom_loads(self, tmp_path, monkeypatch):
+        """A summary hand-edited into "UTF-8 with BOM" (Windows Notepad /
+        PowerShell ``Set-Content -Encoding UTF8``) is valid JSON, not corruption:
+        the BOM is consumed instead of raising MemoryStorageCorruption."""
+        monkeypatch.setenv("DEERMEM_DATA_DIR", str(tmp_path))
+        memory_file = tmp_path / "memory.json"
+        manifest = create_empty_memory()
+        manifest["revision"] = 7
+        manifest["user"]["workContext"] = {"summary": "edited in Notepad"}
+        memory_file.write_bytes(b"\xef\xbb\xbf" + json.dumps(manifest, ensure_ascii=False).encode("utf-8"))
+        assert memory_file.read_bytes().startswith(b"\xef\xbb\xbf"), "fixture must carry a real BOM"
+        storage = FileMemoryStorage(DeerMemConfig())
+        loaded = storage.load()
+        assert loaded["user"]["workContext"]["summary"] == "edited in Notepad"
+
+    def test_summary_without_bom_is_unaffected(self, tmp_path, monkeypatch):
+        """The BOM-tolerant decoder must not alter plain UTF-8 summaries."""
+        monkeypatch.setenv("DEERMEM_DATA_DIR", str(tmp_path))
+        memory_file = tmp_path / "memory.json"
+        manifest = create_empty_memory()
+        manifest["user"]["workContext"] = {"summary": "plain"}
+        memory_file.write_text(json.dumps(manifest, ensure_ascii=False), encoding="utf-8")
+        loaded = FileMemoryStorage(DeerMemConfig()).load()
+        assert loaded["user"]["workContext"]["summary"] == "plain"
+
     def test_save_writes_to_file(self, tmp_path, monkeypatch):
         monkeypatch.setenv("DEERMEM_DATA_DIR", str(tmp_path))
         memory_file = tmp_path / "memory.json"
@@ -323,6 +348,22 @@ class TestMarkdownMemoryStorage:
         assert loaded["revision"] == expected_revision
         assert loaded["user"]["workContext"]["summary"] == "recovered"
 
+    def test_bom_prefixed_valid_json_is_not_quarantined(self, tmp_path):
+        """A BOM does not make the summary unreadable, so the tolerant loader
+        must parse it instead of quarantining recoverable state."""
+        memory_file = tmp_path / "memory.json"
+        manifest = create_empty_memory()
+        manifest["version"] = "2.0"
+        manifest.pop("facts")
+        manifest["revision"] = 7
+        manifest["user"]["workContext"] = {"summary": "kept"}
+        memory_file.write_bytes(b"\xef\xbb\xbf" + json.dumps(manifest, ensure_ascii=False).encode("utf-8"))
+        storage = self._markdown_storage_at(memory_file)
+        loaded = storage.load()
+        assert loaded["revision"] == 7
+        assert loaded["user"]["workContext"]["summary"] == "kept"
+        assert not list(tmp_path.glob("memory.json.corrupt-*")), "a readable summary must not be quarantined"
+
     def test_hand_edited_markdown_without_fence_is_quarantined(self, tmp_path):
         """Markdown without a fenced block cannot be mapped onto the manifest
         schema losslessly: load() must not crash AND must not return an