TBird "search on server" doesn't -- no comm with backend IMAP/SOLR; appears to be local-only search?

[pgnd]

i run

TBird 78.3.3/linx, from upstream

imap backend is

dovecot --version
2.3.11.3 (502c39af9)

with search backend plugin

fts_solr

enabled & functional, connecting to a solr backend

solr-spec 8.6.3
solr-impl 8.6.3 e001c2221812a0ba9e9378855040ce72f93eced4 - jasongerlowski - 2020-10-03 18:12:03
lucene-spec 8.6.3
lucene-impl 8.6.3 e001c2221812a0ba9e9378855040ce72f93eced4 - jasongerlowski - 2020-10-03 18:04:00
JVM Runtime Red Hat, Inc. OpenJDK 64-Bit Server VM 15 15+36

solr scanning/indexing works, as expected, on inbound mail receipt, or manual scan.

cmd line search of mail store works; access/retrieval from solr indexes is logged.

Roundcube webclient search on any header/body also works; again, solr access is logged.

Search from within Tbird -- whether of headers/body -- with "Search on Server" enabled doesn't exec on the server at all.

There's _no_ log traces of any TBird search-related traffic on either the IMAP or SOLR backends; tcpdump verifies it.

attempt to trace IMAP stream in TBird,

NSPR_LOG_MODULES="IMAP:5" NSPR_LOG_FILE="/some/path/to/tbird_imap_log.txt" thunderbird

launches TBird with no errors, but logs nothing to that file.

the 'middle' of this thread @

https://dovecot.org/pipermail/dovecot/2020-October/120273.html

is where the "Tbird doesn't search on server" realizations start.

there's a _very_ old TBird vs IMAP server-search bug referenced,

https://groups.google.com/forum/#!topic/tb-enterprise/TuUXyQLBB1o

i've followed it -- and a number of related bugs -- and have yet to find any indication that the problem was addressed/fixed.


(1) anyone know if/where/when TBIrd server-search most recently has been known/shown to work correctly?

(2) who @ Tbird dev works on backend/server search capability that can be involved in the discussion to resolve this?