Secure file transfer over the environment session, including the terminal

[hahacapital]

Area: apps/web, apps/desktop, apps/mobile

Problem

A remote environment has no way to move a file between the device I am sitting at and the host without a chat message or a separate login.

Chat attachments are the only in-app upload. They land outside the project, a non-image file stops at 50 MiB, and the agent still has to be told where to put the file. Dragging a file onto a thread only fills the composer. The integrated terminal already runs on the host, but dropping a file on it does nothing, and pasting bytes into the shell is not a transfer.

Hosts reached only through T3 Connect often have no inbound SSH, so scp and SFTP are not available. Git clone covers tracked source, not a one-off data file.

Proposed solution

Transfer files over the session that is already connected. Do not open a second SSH channel, and do not create a chat message.

• Mint a short-lived signed URL over the existing RPC, then send the bytes over HTTPS. Same shape as attachment upload. The WebSocket does not carry the payload.
• The claim pins one canonical path. The server resolves it again and rejects a mismatch, a symlink that leaves the workspace, a directory, or a missing parent.
• Upload requires filesystem:write. Download requires filesystem:read. No new scope.
• If the name exists, ask: Replace, keep both (name (1).ext), or skip. The server creates the file exclusively unless the client sent an explicit replace.
• Write to a temp file in the target directory and rename it into place.

Two entry points on that one transport:

1. Terminal. Drop files from the local machine onto the integrated terminal, or use a Transfer action in the terminal panel. The destination is that terminal's current directory. Pulling a path back uses the same action in the other direction, so a file the command just wrote can be saved locally.
2. An explicit destination. Pick a workspace folder and upload there. This can sit beside the Files panel upload in [Feature]: Upload files to a folder from the Files panel #15127; the panel button and the terminal drop should share this transport rather than grow two uploaders.

Out of scope

Folder trees, continuous sync, and replacing Git. Chat attachments stay as they are.

Related

• [Feature]: Upload files to a folder from the Files panel #15127 — upload into the folder selected in the Files panel. This request is the session transport and the terminal entry; the panel button can call the same API.
• Download files from a remote environment (signed download for any readable file) #17605 and [Feature]: Files panel: reveal file in Finder (local) / download file (remote) — copying the path is possible but there's no way to actually get to the file #5532 — download a host file to the client. The download half here should be that, not a second design.
• Attach files — current upload path, which is a chat message.
• Remote access — filesystem:read, filesystem:write, and terminal:operate.