Messages deleted outside of Mutt remain in local index, despite having been removed

[madduck]

Expected Behaviour

If I remove a message from a maildir in one NeoMutt instance (or it is removed using OfflineIMAP), and I have another NeoMutt instance open, I expect the message to disappear from the index.

Actual Behaviour

Instead, the message gets marked D:

and I can still select it in the index, which is what I'd expect for messages marked D as that would indicate that they are flagged for deletion, but not actually deleted yet.

But if I try to open such a message, I get e.g.

/home/madduck/mail/inbox/cur/1718294822_1.616362.lotus,U=349812,FMD5=af1cd994dfcb9286c394d142687ff5a0:2,S
: No such file or directory (errno = 2)

Coming from Mutt, I'd expect the index to update itself and actually just no longer display messages that physically aren't there anymore.

Steps to Reproduce

1. Open two NeoMutt instances on the same Maildir
2. Delete any message in one instance: d$
3. Switch to other NeoMutt instance, hit <Up>
4. Observe how Neomutt reports "Mailbox was externally modified. Flags may be wrong."
5. Observe how the message deleted elsewhere is now marked D
6. Select the message and try to view it

How often does this happen?

• Always

When did it start to happen?

• When I switched to Neomutt from Mutt. I.e. Mutt does this "right" in that it'll remove the message from the index as soon as I interact with the second instance.

NeoMutt Version

NeoMutt 20240425-89-194907
Copyright (C) 2015-2024 Richard Russon and friends
NeoMutt comes with ABSOLUTELY NO WARRANTY; for details type 'neomutt -vv'.
NeoMutt is free software, and you are welcome to redistribute it
under certain conditions; type 'neomutt -vv' for details.

System: Linux 6.7.9-amd64 (x86_64)
ncurses: ncurses 6.5.20240427 (compiled with 6.5.20240427)
libidn2: 2.3.7 (compiled with 2.3.7)
GPGME: 1.18.0
OpenSSL: OpenSSL 3.2.2-dev 
libnotmuch: 5.6.0
storage: tokyocabinet, kyotocabinet, qdbm, rocksdb, gdbm, bdb, tdb, lmdb
compression: lz4, zlib, zstd

Configure options: --bdb --gdbm --gpgme --kyotocabinet --lmdb --lua --lz4 --notmuch --pgp --rocksdb --qdbm --sasl --smime --ssl --tokyocabinet --tdb --zlib --zstd 

Compilation CFLAGS: -std=c11 -fno-delete-null-pointer-checks -D_ALL_SOURCE=1 -D_GNU_SOURCE=1 -D__EXTENSIONS__ -D_XOPEN_SOURCE_EXTENDED -I/usr/include/lua5.4 -I/usr/include -I/usr/include -DNCURSES_WIDECHAR -I/usr/include -I/include -I/usr/include/ -I/usr/include/qdbm -I/usr/include -I/usr/include -I/usr/include -O2

Compile options:
  -autocrypt +fcntl -flock -fmemopen +futimens +getaddrinfo -gnutls +gpgme 
  -gsasl -gss +hcache -homespool +idn +inotify -locales_hack +lua -mixmaster 
  +nls +notmuch +openssl +pgp +regex +sasl +smime -sqlite +truecolor 

MAILPATH="/var/mail"
PKGDATADIR="/usr/share/neomutt"
SENDMAIL="/usr/sbin/sendmail"
SYSCONFDIR="/etc"

Extra Info

• Operating System and its version: Debian sid
• Were you using multiple copies of NeoMutt at once? Yes
• Were you using 'screen' or 'tmux'? No
• Is your email local (maildir) or remote (IMAP)? local Maildir