…opt-in format escape at text node boundaries (facebook#8383)

Co-authored-by: Sergey Gorbachev <grbchv.s@gmail.com>
Co-authored-by: Sherry <potatowagon@meta.com>
Co-authored-by: Bob Ippolito <bob@redivi.com>
Co-authored-by: Agyei Holy <agyeiholy978@gmail.com>
Co-authored-by: Claude <noreply@anthropic.com>

…k#8448)

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… update Links test for adjacent-link merge

The npm→pnpm migration regressed the e2e workflow so the flaky-matrix
job no longer ran the @flaky-tagged tests. The reusable workflow had
hardcoded `--grep-invert "@flaky"` for both the regular and collab test
steps, so the `flaky: true` matrix job ran the same suite as the
non-flaky job (with continue-on-error: true), making it always green.

Make the grep argument depend on `inputs.flaky` so the flaky-matrix job
actually runs the @flaky-tagged tests.

Re-running the flaky tests locally surfaces:
- Links.spec.mjs:410 ("Can create a link with some text after, insert
  paragraph, then backspace, it should merge correctly"): updated the
  post-backspace assertion to match the current adjacent-link merge
  behavior (the two split <a> nodes are now merged back into one when
  the paragraphs join, which is what shouldMergeAdjacentLink does).
- Tab.spec.mjs:22 (Tab + IME) and Toolbar.spec.mjs:43 (Insert image
  caption + table in collab) still fail. They are real bugs that need
  separate fixes; left tagged @flaky so the flaky-matrix job surfaces
  them without blocking CI.

…YJS sync; surface IME keydown for Tab+IME flaky test

Tab.spec.mjs "can tab + IME": call enableCompositionKeyEvents (the same
helper used by Composition/History IME tests) after focusEditor. Without
it, the second CDP imeSetComposition after a TabNode insertion silently
dropped its insertText and the second `すし` never appeared.

lexical-yjs $syncPropertiesFromYjs: when a property already holds a
LexicalEditor (e.g. ImageNode.__caption, built with
buildEditorFromExtensions in the constructor) and YJS delivers a Doc,
reuse the existing editor instead of replacing it with a bare
createEditor(). Replacing it dropped the LexicalBuilder symbol and every
registered extension, so any subsequent render through
LexicalExtensionEditorComposer or getExtensionDependencyFromEditor would
throw "LexicalBuilder.fromEditor: The given editor was not created with
LexicalBuilder" and crash the right frame's React tree.

This unblocks Toolbar.spec.mjs:43 "Insert image caption + table" in
collab mode through the React render path; the remaining caption-text
sync between frames hits a separate dependency-version mismatch in
package.json (yjs@13 client vs @y/websocket-server@0.1.5 needing yjs@14)
and is left for a follow-up.

…et; simplify nested-editor reuse with isLexicalEditor

- Drop @y/websocket-server (its server bin uses yjs@14, which can't
  decode updates from this codebase's yjs@13 client and surfaces as
  "TypeError: store.getClock is not a function" on every WS message,
  silently breaking subdoc sync). Pin y-websocket to ^2.1.0, which
  re-introduces the server bin and stays on yjs@13.
- Update the docs install snippet to drop @y/websocket-server.
- Simplify the nested-editor preservation guard in $syncPropertiesFromYjs
  to use isLexicalEditor(prevValue) (per review).

Status: Tab+IME and Links flaky tests pass; the Toolbar "Insert image
caption + table" collab test no longer crashes the right frame and the
caption editor is now mounted, but the typed caption text still does
not propagate from left to right. Investigation continues.

…g to an empty Yjs doc

When CollaborationPlugin binds an editor that was built with a
non-empty initial state (e.g. a nested editor like ImageNode's caption
editor, which is constructed via buildEditorFromExtensions and starts
with a default empty paragraph) to a fresh empty Yjs doc, bootstrap's
initializeEditor was a no-op because the Lexical root was already
non-empty. The CollabElementNode root then never picked up the
pre-existing paragraph, leaving binding.root._children = [] while
$getRoot() reported [paragraphKey].

On the next edit, syncChildrenFromLexical saw prevChildren=nextChildren
(matching keys), took the "no move/create/remove" branch, and called
_syncChildFromLexical which silently no-oped because
this._children[nextIndex] was undefined and none of the instanceof
branches matched. Result: every transaction ran, the wrapping
binding.doc.transact wrote nothing, no Yjs structs were produced, and
the caption text never propagated to other clients.

Detect that case and create the missing CollabNode (which recursively
exports the Lexical subtree to Yjs via $createCollabNodeFromLexicalNode),
then splice it into the binding. Subsequent typings then sync normally.

This fixes the Toolbar.spec.mjs:43 "Insert image caption + table" test
in collab mode (the third and last @flaky-tagged test that was
deterministically failing once the flaky-matrix CI job was wired up).

…n binding to an empty Yjs doc"

This reverts commit 2ceefb7.

…caption editor in collab mode

CollaborationPlugin's bootstrap only runs initializeEditor when the
Lexical root is empty. The CaptionEditor was built via
buildEditorFromExtensions, where InitialStateExtension's
$defaultInitializer eagerly appends an empty paragraph during
afterRegistration. With that paragraph already there, bootstrap never
runs, so the caption editor's state never gets exported to Yjs and
typed text never propagates to the other client.

Set \$initialEditorState: null on the CaptionEditorExtension so the
caption editor starts with a truly empty root. Now bootstrap runs in
collab mode and adds the paragraph through the normal sync path. In
non-collab mode RichText's normalization handles the empty root by
adding a paragraph as soon as the editor mounts.

This was the last @flaky-tagged test (Toolbar.spec.mjs:43 "Insert image
caption + table") that was deterministically failing once the flaky
matrix CI job was wired up.

…' into feat/code-block-shift-tab-spaces