Its been about I have had running in some capacity for some years by now through a couple of rewrites. At some point Discord added "auto-complete" for commands, this meant that I can do a live lookup and give users a list of comics where some piece of text is.
My index is a bit out of date, but comics before September last year can be searched up.
The search index lives fully in memory as it is not that big since it is only 17363 comics. This does mean that it is rebuilt every startup, but that does not take long compared to the month long uptime it usually has.