The comment above is something I love about HN. I never knew this existed and would not have even thought to search for it but, but that’s something that I see me using everyday.

Glad to be appreciated. You might also enjoy this snippet from my zshrc:

    my-expand() BUFFER=${(e)BUFFER} CURSOR=$#BUFFER
    zle -N my-expand        # Make Alt-E expand environ vars w/o val escape
    bindkey '^[e' my-expand # Allows eVar "short cuts" for history !!:gs etc

As per the comment I did this so that I could have "history substitution expressions" stored in variables, then Alt-E - look (& maybe edit) & ENTER.

The history syntax itself is very cryptic, derived from early 1980s BSD csh. As with most such crypticnesses, figuring it out once, storing it somewhere you can remember, and expanding it on demand is a not awful way to learn it.

But besides cryptic history directives you could also use it for the `$a<Alt-E>` above to "see before you do". You need an extra `$`, though, as written. It would be pretty easy to auto-add a `$` prefix in `my-expand`, though (with Alt-E just becoming a sort of different kind of TAB for expansion rather than completion).