DL-485

The operator downloads through CommsService.GetAttachment: the UI renders an attachment chip with no inline preview and, in a browser, always saves an application/octet-stream Blob and never opens a blob URL; the native shell gains fileService.SaveAttachment, registered in every non-setup mode (the embedded connection keeps its Unix target), which fetches in Go and opens a save dialog so the bytes never cross the JS bridge; the CLI gains compass message attach and compass message get, which refuses an unsafe default filename and never overwrites; the UI does not upload in this record

Status: Active (proposed, pending Matt, 2026-10-11)

Record: ../../agent/compass-comms-file-sharing/design.md#d6-the-operator-downloads-from-the-ui-and-the-cli