dsh-save-button

Usage

The button sits to the right of the official Open button, one per delivered file:

Action	Behavior
Download	first sends HEAD /api/download.button?sessionId=…&seq=…&index=… to probe availability, then hands the file to the browser's download manager with ``; the file name comes from the Host's Content-Disposition
Open	same as official: previews the file in the sidebar
▾ menu	official actions: open in default app / open containing folder (Finder / File Explorer); disabled when the Host has no desktop
On failure	the reason is shown in place (e.g. "file is no longer in this session") and the same button retries
More than 4 files	the official collapse is preserved: All N files / Collapse

Downloads are addressed only by the (sessionId, seq, index) triple — there is no path parameter — so the only files that can be downloaded are the ones this session declared with present. Resolution, containment and type checks, and chunked reads all happen in the Host half. See doc/architecture.md (Chinese).