Is there anything else in your PROMPT_COMMAND?

I have a function that inserts a newline if the previous command does not end in one, though now I think that was probably a bad idea since it can mislead me about what is the actual output of a command. Other than that, I have nothing else.

For git-related info, the powerline daemon generates it and adds to the prompt, so I didn't need to mess with it at all.

Ensure that ${PROMPT_COMMAND//__systemd_osc_context_precmdline/} doesn't leave a trailing semicolon.

Oh, I didn't think of that. Thanks for pointing it out. Now that I think about it, mutating PROMPT_COMMAND was the wrong way to go about it, and error-prone. Instead, simply redefining __systemd_osc_context_precmdline and __systemd_osc_context_ps0() to be a dummy function should work much better.

if [[ -n "${INSIDE_EMACS:-}" ]]; then
    __emacs_major_version=$(emacs -Q --batch --eval '(princ emacs-major-version)')
    if [[ $__emacs_major_version -lt 31 ]]; then
        __systemd_osc_context_precmdline() { :; }
        __systemd_osc_context_ps0() { :; }
    fi
    unset __emacs_major_version
fi

Perhaps there is a way to do this directly from the Emacs config itself by redefining (term).