Two-part root cause for missing photos/filament/cost on large prints
(#972). The configured ftp_timeout was only plumbed through as the FTP
socket timeout; the asyncio.wait_for wrapping run_in_executor stayed on
its 60s hardcoded default, so the user's 300s setting never applied.
Worse, asyncio.wait_for cannot cancel run_in_executor threads — after
the 60s outer timeout fired, the executor thread kept running
ftplib.retrbinary and frequently completed the download ~30–60s later,
but by then the async wrapper had returned False. with_ftp_retry kept
re-attempting the same path, each retry truncating the file the zombie
thread had just written, and the archive was ultimately persisted as a
fallback with no 3MF.
download_file_async now accepts timeout at each call site (plumbed from
ftp_timeout) and salvages post-timeout success via an explicit
completion flag the executor thread sets only after download_to_file
returns True. Per-attempt completion dict so a prot_p zombie can't
flip the flag for a later prot_c attempt. A cosmetic // prefix in the
directory-search download path is also fixed by replacing string
concatenation with posixpath.join.