feat(signals): add prepend option to addEntity

[dimavasylyna]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

The addEntity function in @ngrx/signals currently appends new entities to the end of the entities array by default. There is no way to control the insertion order, limiting flexibility in scenarios where entities need to be added at the beginning (e.g., for "most recent first" displays).

Closes # (No specific issue linked; this is a general enhancement based on potential community needs.)

What is the new behavior?

This PR adds an optional prepend?: boolean parameter to the addEntity function. When prepend: true is specified, the new entity is inserted at the beginning of the entities array instead of being appended to the end. If prepend is omitted or set to false, the existing behavior (appending to the end) is preserved.

Example

// Add entity to the beginning
patchState(store, addEntity(user1, { prepend: true }));
// Result: entities = [user1, ...existingEntities]

// Add entity to the end (default)
patchState(store, addEntity(user2));
// Result: entities = [...existingEntities, user2]

Does this PR introduce a breaking change?

[ ] Yes
[x] No

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[markostanimirovic]

Hi @dimavasylyna,

Can you open a new GitHub issue (feature request) for this feature? Based on the community feedback, we'll decide if this feature should land and how it should be designed. You can find more info on this topic in our contribution guidelines: https://github.com/ngrx/platform/blob/main/CONTRIBUTING.md#submitting-new-features

[dimavasylyna]

Hi @markostanimirovic,
Thanks for the feedback! I’ve opened a new feature request as an RFC issue per the contribution guidelines. You can find it here: RFC: Add prepend option to addEntity in @ngrx/signals/entities #4723. Looking forward to community input on this!