[lexical-text] Bug Fix: a text entity keeps the style and detail of the text it replaces - #9130

Description

registerLexicalTextEntity carries only format from the TextNode it promotes onto the node createNode returns. style and detail are dropped, so a hashtag or a keyword typed inside colored text comes out with the color stripped.

Reproduction, using the test entity node already in the package's unit test:

paragraph.append(
  $createTextNode('#lexical')
    .setFormat('bold')
    .setStyle('color: red')
    .setDetail('directionless'),
);

After the transform runs, the entity node is bold, but getStyle() is '' and isDirectionless() is false.

The inconsistency is inside this same function. $replaceWithSimpleText already chains .setFormat().setStyle().setDetail() when it turns an entity back into plain text. $createAutoLinkNode_ in @lexical/link copies all three as well, off an almost identical splitText sequence. The forward path is the only one that stops at format.

That asymmetry makes the loss permanent, since the reverse path can only give back what the entity node holds. I logged both ends of a full trip on main:

AFTER PROMOTE:     style='' directionless=false bold=true
AFTER BREAK MATCH: text='lexical' style='' directionless=false bold=true

Bold survives typing a hashtag and then editing it back to plain text. The color and the directionless flag don't.

The fix chains setStyle and setDetail onto the setFormat that's already there.

One thing worth calling out: the call is unconditional, so if a caller's createNode sets a style itself, an unstyled source now overwrites it with ''. I kept it unconditional on purpose. The setFormat line has always done exactly that to format, and KeywordNode in the playground already documents that behavior as the contract it relies on. Making style conditional would strand a caller's style on the entity node, and the reverse transform would then copy that style onto the plain text the user is left with, which is worse. Neither caller in this repo sets style or detail in createNode.

Test plan

New unit test in packages/lexical-text/src/__tests__/unit/registerLexicalTextEntity.test.ts, next to the existing test that covers the reverse direction.

Before

$ node_modules/.bin/vitest --project unit --no-watch run packages/lexical-text/src/__tests__/unit/registerLexicalTextEntity.test.ts

 FAIL  |unit| packages/lexical-text/src/__tests__/unit/registerLexicalTextEntity.test.ts > registerLexicalTextEntity > preserves style and detail when promoting simple text to an entity
AssertionError: expected '' to be 'color: red' // Object.is equality

 ❯ packages/lexical-text/src/__tests__/unit/registerLexicalTextEntity.test.ts:72:35
     72|           expect(node.getStyle()).toBe('color: red');

 Test Files  1 failed (1)
      Tests  1 failed | 1 passed (2)

Dropping the style assertion so the next one runs shows detail is gone too:

AssertionError: expected false to be true // Object.is equality

 ❯ packages/lexical-text/src/__tests__/unit/registerLexicalTextEntity.test.ts:72:42
     72|           expect(node.isDirectionless()).toBe(true);

After

$ node_modules/.bin/vitest --project unit --no-watch run packages/lexical-text/src/__tests__/unit/registerLexicalTextEntity.test.ts

 Test Files  1 passed (1)
      Tests  2 passed (2)

The packages around it, all green:

$ node_modules/.bin/vitest --project unit --no-watch run packages/lexical-text packages/lexical-hashtag packages/lexical-link packages/lexical-mark packages/lexical-playground/__tests__/unit/KeywordNode.test.ts

 Test Files  23 passed (23)
      Tests  844 passed (844)

I read the e2e specs instead of running them. Keywords.spec.mjs asserts style="cursor: default;" on the keyword span, and that comes from KeywordNode.createDOM, not from the node's style. Carrying an empty style over changes nothing there: createDOM skips the write when the style is '', updateDOM skips it when the style hasn't changed, and setDOMStyleFromCSS sets individual properties rather than replacing cssText, so cursor is never clobbered either way. Hashtags.spec.mjs and the hashtag regression specs assert no style attribute at all, and none of these specs applies a text color before typing. I don't expect any of those snapshots to move.