Python 3.13 negotiates TLS 1.3 by default. The P2S firmware 01.02.00.00
vsFTPd build doesn't tolerate TLS 1.3's async session-ticket model on
the FTPS data channel — session resumption races, the data channel gets
torn down mid-stream, uploads land truncated at a chunk boundary, and
the printer replies 426 instead of 226. Visible to the user as "unable
to parse 3mf file" 30 s into the print.
Capping the SSL context's maximum_version to TLS 1.2 makes session
resumption synchronous and uploads complete normally.
Follow the per-model pattern established by camera_profiles.py in the
#1395 follow-up: add backend/app/services/ftp_profiles.py with a frozen
FTPProfile dataclass and a per-model registry. Only P2S (display name
+ N7 SSDP code) gets the cap today. X1C, H2D, P1S, A1 stay on negotiated
TLS 1.3 — the maintainer's dogfooded printers see zero behaviour change.