diff --git a/nextcloud_mcp_server/client/webdav.py b/nextcloud_mcp_server/client/webdav.py
index 78ce64b2..19b654d4 100644
--- a/nextcloud_mcp_server/client/webdav.py
+++ b/nextcloud_mcp_server/client/webdav.py
@@ -54,6 +54,11 @@ class WebDAVClient(BaseNextcloudClient):
         Percent-encodes the caller-supplied portion (see ``_encode_dav_path``)
         so names with ``#``, commas, or spaces don't truncate/404; the base
         ``/remote.php/dav/files/<user>`` segment is left as-is.
+
+        Precondition: ``path`` is a **decoded** path (the convention everywhere
+        in this client — PROPFIND/REPORT hrefs are ``unquote``d before storage,
+        and MCP-tool inputs are raw). It is encoded exactly once, so passing an
+        already-encoded path would double-encode it (``%20`` → ``%2520``).
         """
         return f"{self._get_webdav_base_path()}/{_encode_dav_path(path.lstrip('/'))}"
 
diff --git a/tests/unit/client/test_webdav.py b/tests/unit/client/test_webdav.py
index b1268f2f..cf8a3871 100644
--- a/tests/unit/client/test_webdav.py
+++ b/tests/unit/client/test_webdav.py
@@ -517,6 +517,29 @@ def _request_url(mock_http_client) -> str:
     return mock_http_client.request.call_args[0][1]
 
 
+@pytest.mark.unit
+@pytest.mark.parametrize(
+    "path, expected",
+    [
+        ("", "/remote.php/dav/files/testuser/"),
+        ("/Documents/notes.txt", "/remote.php/dav/files/testuser/Documents/notes.txt"),
+        ("Documents/notes.txt", "/remote.php/dav/files/testuser/Documents/notes.txt"),
+        ("a/b #1.pdf", "/remote.php/dav/files/testuser/a/b%20%231.pdf"),
+        ("law/x, y  z.pdf", "/remote.php/dav/files/testuser/law/x%2C%20y%20%20z.pdf"),
+        (
+            "学生邮箱/r.pdf",
+            "/remote.php/dav/files/testuser/%E5%AD%A6%E7%94%9F%E9%82%AE%E7%AE%B1/r.pdf",
+        ),
+    ],
+)
+def test_webdav_path_encoding(path, expected):
+    """_webdav_path encodes the decoded caller path once, preserving '/', and
+    strips a leading slash. Every caller-path builder routes through this, so
+    it is the single source of truth for their encoding."""
+    client = WebDAVClient(AsyncMock(), "testuser")
+    assert client._webdav_path(path) == expected
+
+
 @pytest.mark.unit
 async def test_read_file_encodes_special_chars(mocker):
     """read_file must percent-encode '#', commas, and spaces in the path (card 309).