fix: support Windows filesystem paths

open_terminal/main.py

@@ -650,7 +650,9 @@ async def view_file(
 )
 async def serve_file(path: str, fs: UserFS = Depends(get_filesystem)):
     """Path-based alias for view_file — enables relative URL resolution in iframes."""
-    return await view_file(path=f"/{path}", fs=fs)
+    if not (path.startswith("/") or (len(path) >= 2 and path[1] == ":")):
+        path = f"/{path}"
+    return await view_file(path=path, fs=fs)
 
 
 @app.post(

open_terminal/utils/fs.py

@@ -192,7 +192,7 @@ def _is_writable_sync(self, path: str) -> bool:
             pass
         try:
             return os.access(path, os.W_OK, effective_ids=True)
-        except TypeError:
+        except (TypeError, NotImplementedError):
             return os.access(path, os.W_OK)
 
     async def is_writable(self, path: str) -> bool:

tests/test_windows_compatibility.py

@@ -0,0 +1,29 @@
+import os
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+os.environ.setdefault("OPEN_TERMINAL_API_KEY", "test-key")
+
+from open_terminal.main import serve_file
+from open_terminal.utils.fs import UserFS
+
+
+@pytest.mark.asyncio
+async def test_serve_file_preserves_windows_drive_path():
+    filesystem = object()
+    with patch("open_terminal.main.view_file", new_callable=AsyncMock) as view_file:
+        await serve_file("C:/Users/test/index.html", filesystem)
+
+    view_file.assert_awaited_once_with(path="C:/Users/test/index.html", fs=filesystem)
+
+
+def test_is_writable_falls_back_when_effective_ids_are_unsupported():
+    filesystem = UserFS(home="C:/Users/test")
+    path = "C:/Users/test"
+
+    with patch.object(os, "access", side_effect=[NotImplementedError, True]) as access:
+        assert filesystem._is_writable_sync(path) is True
+
+    assert access.call_count == 2
+    assert access.call_args_list[1].kwargs == {}