LaTeX Suggestions (inline tracked edits)

Propose concrete replacement text the author sees as struck-through old + colored new, and can accept or reject, the original stays visible until they decide. Never silently overwrite. It renders as normal typeset text (via ulem), so it shows in any PDF viewer including the Papyrus preview, no package to install, no PDF annotations. See papyrus-writing for behaviour. Pair every suggestion with a papyrus-latex-comments \aicomment saying WHY.

Step 1, Setup (idempotent)

ulem and xcolor ship with TeX Live, no tlmgr install. If the document has no suggestion preamble yet, inject this once at the end of the preamble, after all existing \usepackage lines (never duplicate it if it is already there):

% Load ulem/xcolor ONLY if the document hasn't already loaded them (avoids an option clash).
\makeatletter
\@ifpackageloaded{ulem}{}{\usepackage[normalem]{ulem}}   % \sout (strike) + \uline (underline); normalem keeps \emph italic
\@ifpackageloaded{xcolor}{}{\usepackage{xcolor}}         % \color for the strike/insert colors
\makeatother
% ==== Papyrus suggestion layer ====
% Flip to \showeditsfalse to render the FINAL text only (visually accepts every change).
\newif\ifshowedits \showeditstrue
\newcommand{\aisuggest}[3][]{\ifshowedits{\color{red}\sout{#2}}\,{\color{blue}#3}\else#3\fi}
\newcommand{\txadd}[2][]{\ifshowedits{\color{blue}\uline{#2}}\else#2\fi}
\newcommand{\txremove}[2][]{\ifshowedits{\color{red}\sout{#2}}\else\fi}
% =====================================================================================

The optional [...] first argument carries metadata (author=papyrus, id=R12, status=pending): it documents the change, but it is not rendered.