[lexical-code][lexical-playground] Bug Fix: Prevent formatting on TabNode inside code blocks

[mayrang]

Description

The floating text format toolbar shows when selecting a TabNode inside a code block, and formatting (bold, highlight, etc.) sticks. CodeHighlightNode already blocks this via a no-op setFormat(), but TabNode inherits from TextNode and has no such guard.

Fix

CodeExtension now registers a registerNodeTransform(TabNode, ...) that strips format back to 0 when the parent is a CodeNode. A global TabNode.setFormat() override was not used because TabNode legitimately inherits format in normal paragraphs (the existing INSERT_TAB_COMMAND test verifies this).

The FloatingTextFormatToolbarPlugin guard is simplified from checking both $isCodeHighlightNode(anchor) and $isCodeNode(anchor.getParent()) to just $isCodeNode(anchor.getParent()) — the latter is a superset since CodeHighlightNode always has a CodeNode parent.

Closes #8749

Test plan

• pnpm vitest run --project unit -t "CodeExtension" — 5 pass (including new "should strip format from TabNode inside CodeNode").
• pnpm vitest run --project unit -t "TabNode" — 23 pass, no regression.
• pnpm tsc --noEmit clean.
• Manual playground:
  • Tab inside code block → select → no floating toolbar.
  • Tab in normal paragraph → formatting still works as before.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
lexical	Ready	Preview	Jun 26, 2026 3:36pm
lexical-playground	Ready	Preview	Jun 26, 2026 3:36pm

[potatowagon]

Reviewed by Navi (Tater Thoughts Bobblehead) on behalf of @potatowagon.

Assessment: LGTM ✅ — Clean, targeted fix with good test coverage.

What this PR does

Prevents text formatting (bold, italic, etc.) from being applied to TabNode elements inside code blocks, and fixes the floating text format toolbar to correctly suppress itself when the selection is inside a code block.

What I checked

1. Logic correctness:

   • The registerNodeTransform(TabNode, ...) approach is correct — it reactively strips formatting (setFormat(0)) whenever a TabNode inside a CodeNode has non-zero format. This covers all mutation paths (user applying format, paste, collaboration sync).
   • The parent check $isCodeNode(node.getParent()) is the right level — TabNodes are direct children of CodeNode, not nested deeper.
   • The toolbar fix changes from $isCodeHighlightNode(selection.anchor.getNode()) to $isCodeNode(selection.anchor.getNode().getParent()). This is more robust — the old check only caught CodeHighlightNode but missed TabNode (which is also a direct child of CodeNode). The new check catches ANY node whose parent is CodeNode.

2. Edge cases:

   • node.getParent() could return null if the node is detached, but $isCodeNode(null) safely returns false — no crash risk.
   • The transform only fires when node.getFormat() !== 0, avoiding unnecessary writes/re-triggers.
   • mergeRegister correctly composes the existing KEY_ENTER_COMMAND handler with the new node transform — cleanup is properly handled.

3. Test coverage:

   • New unit test should strip format from TabNode inside CodeNode properly exercises the transform: creates a tab inside code, applies format, then verifies it gets stripped back to 0. Uses {discrete: true} for synchronous verification.

4. No regressions:

   • The toolbar change is playground-only (not library code), and the logic is strictly more correct (suppresses toolbar for all code-block children, not just CodeHighlightNode).
   • Unit tests pass on Node 22.x and 24.x. Browser tests pass. CLA signed. Vercel deploys pass.

5. www compat:

   • No removed/renamed exports. $isCodeNode was already exported. mergeRegister and TabNode already exported from lexical. No breaking changes to public API.

CI status: Core unit + browser tests all green. Integrity check and one e2e canary still pending — recommend waiting for those to finish before merging, but no red flags.

Ready to approve once remaining CI checks complete.