[Bug report] Abbreviations with regex characters break syntax highlighting

[cohml]

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Expected Behavior

I have some aliases that end in +, a signal to me that they "force" something. For example:

❯ grep '+"' $ABBR_USER_ABBREVIATIONS_FILE
abbr -g "git p+"="git push origin +\"\$(git branch --show-current)\""
abbr "rm+"="rm -rfv"

Separately, I also have syntax highlighting enabled pretty much exactly as recommended in the documentation:

The expectation was that this should trigger highlighting whenever I type my abbreviations:

❯ rm+
❯ git p+

Actual Behavior

However, the presence of + in my abbreviation seems to confuse the highlighting algorithm. Specifically, it seems to treat this as a regex repetition operator, not as a literal plus. As a result, e.g., rm+ is not highlighted, meanwhile all of the following are highlighted (note: none of these are abbreviations):

rm
rmm
rmmm
rmmmm
rmmmmmmmmmmmmmmmm
git p
git ppppp

Steps To Reproduce

Source this on terminal startup (e.g., from .zshrc):

(( "${#ABBR_REGULAR_USER_ABBREVIATIONS}" )) && {
  ABBR_HIGHLIGHTS="fg=black,bold,bg=cyan"
  ZSH_HIGHLIGHT_HIGHLIGHTERS+=(regexp)
  ZSH_HIGHLIGHT_REGEXP=('^[[:blank:][:space:]]*('${(j:|:)${(Qk)ABBR_REGULAR_USER_ABBREVIATIONS}}')$' "${ABBR_HIGHLIGHTS}")
  ZSH_HIGHLIGHT_REGEXP+=('[[:<:]]('${(j:|:)${(Qk)ABBR_GLOBAL_USER_ABBREVIATIONS}}')$' "${ABBR_HIGHLIGHTS}")
}

Environment

❯ abbr profile
zsh-abbr version 6.4.0
zsh 5.9 (arm64-apple-darwin25.0)
OSTYPE darwin25.0

Installation method

Homebrew

Installation method details

No response

Anything else?

If this is corner case could be handled on zsh-abbr's side, that would be ideal.

However, I suspect the patch must reside within zsh-syntax-highlighting. In that case, perhaps you could at least acknowledge this behavior in the Known limitations block of the documentation.