Fix 341291: Handle enter key next to Entity

[JiuqingSong]

When cursor is next to entity, since there is entity delimiter, sometimes the existing DOM operation code is not handling well. So let's handle it using Content Model.

1. When there is entity (or possibly has entity), use Content Model to handle enter key. To make the check fast enough, we just check one of the following:
   a. Current paragraph has entity, even it is not next to cursor
   b. Current paragraph is implicit, since this can happen when focus is next to block entity. Although it is possible these can be false positive, but it is fine since ideally we can handle enter key in all scenarios
2. There is a problem in dom indexer that after restoring undo snapshot, we are reusing entity delimiter DOM nodes and it can have cached indexer which is already out-of-date, so we need to clear it
3. When handle the enter key, if current paragraph is implicit and only has selection marker, we should not mark it as not implicit since that will introduce additional empty line

This pr fix all issues above to make sure enter key is correctly handled around entity.

Before

[Copilot]

Pull Request Overview

This PR fixes issue 341291 by improving the handling of the Enter key when the cursor is next to an entity. The changes include updating the Content Model handling in splitParagraph and keyboardEnter, adding logic to clear cached index data for entity delimiters after undo snapshot restoration, and revising tests across the plugins and core modules to support these enhancements.

Reviewed Changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/roosterjs-content-model-plugins/lib/edit/keyboardEnter.ts	Updated Enter key handling to include entity-based conditions.
packages/roosterjs-content-model-plugins/lib/edit/utils/splitParagraph.ts	Adjusted behavior for implicit paragraphs with a selection marker.
packages/roosterjs-content-model-core/lib/corePlugin/entity/entityDelimiterUtils.ts	Refactored Enter key event handling for entity delimiters.
packages/roosterjs-content-model-core/lib/corePlugin/cache/domIndexerImpl.ts	Added clearIndex method to remove outdated cached index data.
packages/roosterjs-content-model-core/test/coreApi/restoreUndoSnapshot/restoreSnapshotHTMLTest.ts	Added tests to verify that delimiter indexes are cleared upon restoring snapshots.
Other test files in domToModel and modelToDom processors	Included clearIndex in test contexts to support the updated cache handling.

Comments suppressed due to low confidence (2)

packages/roosterjs-content-model-core/test/corePlugin/entity/entityDelimiterUtilsTest.ts:451

• Tests related to handling range selections with entity delimiters were removed. Please confirm that the new behavior for Enter key handling around entities is thoroughly covered by the updated test suite.

it('Handle, range selection & delimiter before wrapped in block entity | Enter Key', () => {

packages/roosterjs-content-model-core/lib/corePlugin/entity/entityDelimiterUtils.ts:219

• The refactoring in the Enter key handling removed the branch for collapsed range handling. Please ensure that this change fully aligns with the intended design and that tests adequately cover both expanded and collapsed selection scenarios around entity delimiters.

if (entity && isNodeOfType(entity, 'ELEMENT_NODE') && helper.isNodeInEditor(entity)) {

[Copilot]

[nitpick] The enhanced condition to trigger handleEnterOnParagraph when a paragraph meets entity-related criteria is clear but could benefit from an inline comment explaining that it covers cases where the paragraph is implicit or contains a selection marker.