README.md: link to Overleaf CM 6 math rendering

also rewrote/shortened some outdated parts

Author: cben

README.md

@@ -1,19 +1,9 @@
-# UPDATE: See the more mature https://github.com/SamyPesse/codemirror-widgets
+# CodeMirror 5.x + in-place MathJax 2.x
 
-codemirror-widgets powers [GitBook's new desktop editor](https://www.gitbook.com/blog/releases/editor-5-beta),
-is abstracted to supports rendering in-place various things (math, links, images),
-and seems generally well structured.
+Experimenting to replace `$math$` (and related LaTeX syntaxes) with rendered formulas in CodeMirror 5.
+See open issues, has known bugs!
 
-I haven't carefully reviewed codemirror-widgets yet, but I'll probably abandon this project in favor of improving codemirror-widgets, and switch [mathdown](https://github.com/cben/mathdown) to it too.
-
-# Attempt at CodeMirror + in-place MathJax
-
-Experimenting to replace $math$ (and related LaTeX syntaxes) with formulas in CodeMirror.
-Buggy and work-in-progress...
-
-Mostly tested with CodeMirror 4.x, 5.x versions but probably works with 3.x too.
-
-Performance is currently OK with MathJax 2.4, horribly slow with 2.5 or 2.6.  Working on it...
+> ⚠ Not _fully_ abandoned, but close to it, I barely touched this in a decade ⚠
 
 ## Demo
 
@@ -36,4 +26,25 @@ I'm directly working in `gh-pages` branch without a `master` branch,
 as that's the simplest thing that could possibly work;
 http://oli.jp/2011/github-pages-workflow/ lists several alternatives.
 
-TODO: learn about bower or other ways to manage local vs online deps.
+TODO: learn about ~~bower~~ publishing frontend code to npm
+
+----
+
+# Alternatives
+
+## CodeMirror 5.x: the more mature https://github.com/SamyPesse/codemirror-widgets ?
+
+codemirror-widgets powered [GitBook's 2016 desktop editor beta](https://web.archive.org/web/20160404071819/https://www.gitbook.com/blog/releases/editor-5-beta), dunno what happened later.
+
+It's abstracted to supports rendering in-place various things (math, links, images), and seems generally well structured.  
+IIRC it was more systematic in some ways (e.g. multi-line formula support).  But it's been dormant since 2016 too.
+
+## CodeMirror 6: Look at how Overleaf does it
+
+https://Overleaf.com renders to PDF by real LaTeX, but can also render math in the editor, and is very battle-tested!
+
+They've long been on CodeMirror 6, and in June 2026 [upgraded to MathJax 4](https://github.com/overleaf/overleaf/commits/757735b07518ffc157ae3b2abe8307beb14198a2/services/web/frontend/js/features/mathjax/load-mathjax.ts).
+
+- in "Code" mode they render current formula as tooltip preview: https://github.com/overleaf/overleaf/blob/757735b07518ffc157ae3b2abe8307beb14198a2/services/web/frontend/js/features/source-editor/extensions/math-preview.ts#L115-L137
+- in "Visual" mode they do a lot of inline styling of markdown + render all formulas. I think mostly implemented here: https://github.com/overleaf/overleaf/blob/757735b07518ffc157ae3b2abe8307beb14198a2/services/web/frontend/js/features/source-editor/extensions/visual/atomic-decorations.ts  
+  (CM 5 API had "widgets"; CM 6 has "decorations" that may `replace` text + ability to mark ranges as "atomic" for cursor movement)