[Breaking Change][lexical-code] Bug Fix: move code block escape logic to KEY_ENTER_COMMAND listener

[anikakpillai]

Breaking Changes

The "press enter three times to exit the CodeNode" logic has been moved from CodeNode.insertNewAfter to a KEY_ENTER_COMMAND listener registered by CodeExtension.

Using CodeNode without CodeExtension is now deprecated to allow this functionality to be moved to a command listener. There is a shim in the implementation that will provide backwards compatible behavior and log a warning (in dev) when this scenario is encountered, but you should expect that the node will eventually stop working correctly in a future version if your editor uses CodeNode without CodeExtension.

Description

When pasting text containing consecutive blank lines into a code block,
content after the blank lines incorrectly escapes the code block and
appears as top-level paragraphs.

The root cause was that the escape-to-paragraph logic in
CodeNode.insertNewAfter ran on all content changes, including paste.

Per maintainer feedback, this fix takes the preferred approach of moving
the escape logic out of insertNewAfter entirely and into a
KEY_ENTER_COMMAND listener registered in CodeExtension. This ensures
the escape behavior only triggers on keyboard input, not paste or other
programmatic changes.

Closes #8351

Test plan

Before

Paste text with consecutive blank lines into a code block — content
after the blank lines escapes to a top-level paragraph.

After

• Pasted content stays inside the code block
• Pressing Enter at the end of a code block after two blank lines
  still correctly exits to a new paragraph
• Four unit tests added covering: escape on Enter, no escape on paste,
  no escape with single blank line, no escape when cursor is not at end

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Project	Deployment	Actions	Updated (UTC)
lexical	Ready	Preview, Comment	Apr 17, 2026 4:45am
lexical-playground	Ready	Preview, Comment	Apr 17, 2026 4:45am

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[etrepum]

Generally speaking it's better if PRs add tests to demonstrate that they work as intended

[anikakpillai]

Thanks for the review! I've updated the approach per your original suggestion on the issue. The escape logic is now moved out of insertNewAfter entirely and into a KEY_ENTER_COMMAND listener in CodeExtension, so it only fires on keyboard input. Added 4 unit tests as well.

[etrepum]

Your latest changes fail integrity checks (looks like type errors) and existing end-to-end tests

[etrepum]

This looks good, but I think we will have to think about the compatibility scenarios here since it is a breaking change, if you are using CodeNode in a legacy app that is not using CodeExtension then you will lose the functionality to exit the CodeNode by pressing return three times.