Description

Background

I am currently looking into Issue MO-4341 regarding backend-based file duplication.

Current Issues

1. Insufficient Backend File Operations:

   The backend's file system API in marimo/_server/api/endpoints/file_explorer.py currently supports create, delete, and move operations, but copy is missing.

2. Heavy Frontend Workload:

   Because of the missing backend support, the handleDuplicate function in frontend/src/components/editor/file-tree/file-explorer.tsx currently performs a "download then upload" round-trip.

   • It fetches the full file content from the backend to the frontend.
   • It immediately sends it back to the backend as a new file with a different name.
     This is highly inefficient for large files and consumes unnecessary network bandwidth and memory.

3. Session-Locked Copy Endpoint:

   While there is an existing /api/kernel/copy endpoint in marimo/_server/api/endpoints/files.py, it is tied to an active notebook session (app_state.require_current_session()). This makes it unusable for general workspace operations in the file explorer where a session might not exist.

Suggested solution

Introduce a general-purpose copy endpoint in marimo/_server/api/endpoints/file_explorer.py that:

• Does not require an active notebook session.
• Supports both files and directories.
• Leverages server-side utilities like shutil.copy2 and shutil.copytree via OSFileSystem.

[!NOTE]
Copy logic is already implemented in marimo/_server/files/os_file_system.py within the safe_move function as a fallback mechanism. This makes the implementation of a copy operation very straightforward and consistent with existing patterns in the codebase.

If this proposal is acceptable, I would like to submit a PR for these changes.

Are you willing to submit a PR? (You must receive approval from the team before submitting a PR.)

• Yes

Alternatives

No response

Additional context

No response