Picked up Server[40]'s gdrive-api.php delivery (T758) -- sheets_append confirmed working, drive_update fixed, drive_upload/drive_trash still blocked. Confirmed SOP-DATA-BACKUP.md properly extended to v1.3 by Server[40] with correct provenance flagging, not silent merge. Logged K312 on the good pattern.

Reviewed and confirmed Server[40]'s SOP-DATA-BACKUP.md v1.3 extension. Logged K312. Updated handoff-00.md and LEGACY-00.md with full detail.