[docs-infra] replace live editing engine back to textarea

[brijeshb42]

Replaces the docs-infra live editing stack with a lazy react-simple-code-editor textarea implementation, as discussed in code-infra meetings. The runtime functionality is in parity with what we have on current core docs site while keeping improvements from the current docs-infra like no need of separate preview files, no js files for ts file, etc.

• Removes the contentEditable-based editing engine, related state machines, transition logic, and obsolete tests. I'll revisit it separately to move back to content-editable based editor.
• Lets collapsed code blocks edit only their visible lines while applying changes to the full source file.
• Preserves live preview builds, source transforms, reset behavior, copy/export actions, syntax highlighting, worker parsing, and controller integration, in parity with core-docs.
• Updates CodeProvider lazy loading to preload the editor only for editable code blocks.
• Refreshes docs-infra demos, styles, API docs, and live-editing examples for the new editor behavior.
• Converts applicable production React.createElement usage to JSX and renames JSX-bearing modules to .tsx. Just minor housekeeping.
• Removes the internal useCrossTabState / useCrossTabMirror API, tests, demo, package export, and documentation. This wasn't being used anywhere and I doubt we'll need it for any future feature.

Companion PR commits to review in material-ui migration.

[code-infra-dashboard]

Deploy preview

• docs/app/docs-infra/components/code-controller-context/page.mdx

  
  
• docs/app/docs-infra/components/code-provider/page.mdx

  
  
• docs/app/docs-infra/components/page.mdx

  
  
• docs/app/docs-infra/hooks/page.mdx

  
  
• docs/app/docs-infra/hooks/use-code/page.mdx

  
  

Bundle size

Total Size Change: ▼-145KB^(-4.03%) - Total Gzip Change: ▼-44.5KB^(-4.90%)
Files: 75 total (6 added, 2 removed, 19 changed)

Show details for 75 more bundles

CodeHighlighterClient parsed: 🔺+481B^(+0.82%) gzip: 🔺+196B^(+0.97%)
@mui/internal-docs-infra/useDemoController parsed: 🔺+413B^(+7.65%) gzip: 🔺+113B^(+4.99%)
rolldown-runtime parsed: 🔺+390B^(+56.20%) gzip: 🔺+199B^(+47.16%)
loadIsomorphicCodeVariant parsed: 🔺+333B^(+1.29%) gzip: 🔺+154B^(+1.73%)
TransformEngine parsed: 🔺+268B^(+1.36%) gzip: 🔺+70B^(+1.10%)
@mui/internal-docs-infra/abstractCreateDemo parsed: 🔺+188B^(+3.15%) gzip: 🔺+41B^(+1.70%)
CodeHighlighterChunk parsed: 🔺+107B^(+1.55%) gzip: 🔺+29B^(+1.12%)
@mui/internal-docs-infra/createDemoData parsed: 🔺+33B^(+1.35%) gzip: 🔺+10B^(+0.92%)
hastUtils parsed: 🔺+45.6KB^(new) gzip: 🔺+16.7KB^(new)
CodeEditor parsed: 🔺+13.3KB^(new) gzip: 🔺+5.4KB^(new)
SourceEditingEngine parsed: 🔺+2.94KB^(new) gzip: 🔺+1.25KB^(new)
grammarMaps parsed: 🔺+1.83KB^(new) gzip: 🔺+887B^(new)
useGrammarsReady parsed: 🔺+1.63KB^(new) gzip: 🔺+779B^(new)
grammarCache parsed: 🔺+797B^(new) gzip: 🔺+419B^(new)
@mui/internal-docs-infra/useCode parsed: ▼-67.4KB^(-61.58%) gzip: ▼-22.7KB^(-62.40%)
@mui/internal-docs-infra/useDemo parsed: ▼-67KB^(-52.28%) gzip: ▼-22.5KB^(-52.85%)
@mui/internal-docs-infra/CodeHighlighter parsed: ▼-28.9KB^(-87.29%) gzip: ▼-9.69KB^(-84.97%)
@mui/internal-docs-infra/CodeProvider parsed: ▼-24KB^(-15.11%) gzip: ▼-7.39KB^(-15.81%)
embedTransforms parsed: ▼-477B^(-4.77%) gzip: ▼-47B^(-1.30%)
parseSource parsed: ▼-320B^(-0.37%) gzip: ▼-248B^(-0.97%)
findExpandingRanges parsed: ▼-179B^(-1.11%) gzip: ▼-52B^(-1.02%)
@mui/internal-docs-infra/abstractCreateDemoClient parsed: ▼-122B^(-14.35%) gzip: ▼-16B^(-3.49%)
BuildEngine parsed: ▼-24B^(-0.32%) gzip: ▼-2B^(-0.07%)
@mui/internal-docs-infra/abstractCreateTypes parsed: ▼-23B^(-0.02%) gzip: ▼-6B^(-0.02%)
grammarLoaders parsed: ▼-5B^(-0.58%) gzip: ▼-4B^(-1.60%)
EditingEngine parsed: ▼-23.6KB^(removed) gzip: ▼-7.61KB^(removed)
@mui/internal-docs-infra/useCrossTabState parsed: ▼-924B^(removed) gzip: ▼-488B^(removed)
@mui/internal-docs-infra/abstractCreateStream parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/ChunkProvider parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/cli parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/CodeControllerContext parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/CodeExternalsContext parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/CodeHighlighter/errors parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/CodeHighlighter/types parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/CoordinatedLazy parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/CoordinatedLazy/types parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/createDemoData/types parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/createSitemap parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/createSitemap/types parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useCodeWindow parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useCoordinated parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useCopier parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useErrors parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useLocalStorageState parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/usePreference parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useScrollAnchor parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useSearch parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useSearch/types parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useStream parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useStream/types parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useType parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useTypes parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/useUrlHashState parsed: 0B^(0.00%) gzip: 0B^(0.00%)
@mui/internal-docs-infra/withDocsInfra parsed: 0B^(0.00%) gzip: 0B^(0.00%)
addLineGutters parsed: 0B^(0.00%) gzip: 0B^(0.00%)
CodeInitialSourceLoader parsed: 0B^(0.00%) gzip: 0B^(0.00%)
CodeSourceLoader parsed: 0B^(0.00%) gzip: 0B^(0.00%)
compileCssWithPostcss parsed: 0B^(0.00%) gzip: 0B^(0.00%)
createFrame parsed: 0B^(0.00%) gzip: 0B^(0.00%)
createParseSourceWorkerClient parsed: 0B^(0.00%) gzip: 0B^(0.00%)
enhanceCodeEmphasis parsed: 0B^(0.00%) gzip: 0B^(0.00%)
getHastTextContent parsed: 0B^(0.00%) gzip: 0B^(0.00%)
grammars parsed: 0B^(0.00%) gzip: 0B^(0.00%)
isFrameSpan parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.css parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.js parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.json parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.mdx parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.shell parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.ts parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.tsx parsed: 0B^(0.00%) gzip: 0B^(0.00%)
source.yaml parsed: 0B^(0.00%) gzip: 0B^(0.00%)
text.html.basic parsed: 0B^(0.00%) gzip: 0B^(0.00%)
text.md parsed: 0B^(0.00%) gzip: 0B^(0.00%)
transpileSource parsed: 0B^(0.00%) gzip: 0B^(0.00%)

Details of bundle changes

Performance

Total duration: 13.80 ms -1.58 ms^(-10.3%) | Renders: 5 ⁽⁺⁰⁾ | Paint: 53.87 ms -3.44 ms^(-6.0%)

Test	Duration	Renders
HeavyList mount	5.40 ms ▼-1.77 ms(-24.7%, p=0.001)	1 (+0)

6 tests within noise — details

---

Check out the code infra dashboard for more information about this PR.

[Janpot]

@claude review

(testing the new action)