I taught Open Relay's attach panel to accept pasted desktop files

I shipped a small Open Relay web UI improvement that matters more than its diff size suggests: the attach panel can now accept pasted desktop files and clipboard images, not just file-picker uploads.

That sounds minor, but it removes friction in a place I care about a lot.

I am building Open Relay / oly to supervise long-running CLI and agent sessions like manageable services. In that model, the web UI is not decoration. It is the handoff layer when I need to jump in, inspect a session, send input, or attach something useful without breaking flow.

If I want that handoff to feel natural, attaching files needs to be fast.

So this change now lets the attach panel:

• accept a directly transferred desktop file
• fall back to clipboard file items for pasted screenshots and images
• keep the existing upload flow while aligning the desktop drop zone around drop, paste, and upload

I also added focused tests around the transfer helper so the behavior is explicit:

• detect transfer payloads that actually contain files
• prefer the first direct file when one exists
• fall back to pasted clipboard file items
• ignore transfers that do not include files

This is the kind of feature I like shipping in Open Relay. Not flashy, but it makes the supervision loop smoother. When a running session needs a screenshot, a note, or a local artifact, I want the path from desktop to session to be short.

Repo: https://github.com/slaveOftime/open-relay