Introduce callback to customize how new activities are handled in a feed

[gpunto]

Goal

Concludes AND-893

The feature is described here, but the summary is that usually feed apps don't automatically add new activities in a live fashion. It usually happens only when the current user posts a new activity, so this is going to be our default behavior. However, we are also adding a way to customize it, should the integrators choose to do so.

Implementation

• Add onNewActivity property in FeedQuery
• Update Feed event handler & state to honor the action returned by onNewActivity

Testing

In the sample, you can try adding an activity from the current user and from another user (in a different device) and verify that only in the first case is the activity added to the (top of the) feed.

Checklist

• Issue linked (if any)
• Tests/docs updated
• I have signed the Stream CLA (required for external contributors)

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled.

🎉 Great job! This PR is ready for review.

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-feeds-android-client	2.36 MB	2.36 MB	0.00 MB	🟢

[Copilot]

Pull Request Overview

This PR introduces a customizable callback mechanism to control how new activities from WebSocket events are added to feeds. By default, only activities created by the current user that match the feed's activity filter are automatically inserted at the start of the feed, while all other activities are ignored. This behavior can be customized via the onNewActivity callback parameter in FeedQuery.

• Added InsertionAction enum to specify whether and where to insert new activities
• Introduced onNewActivity callback in FeedQuery with a sensible default implementation
• Updated event handling pipeline to use the callback and honor insertion actions

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
InsertionAction.kt	Defines the enum for specifying insertion behavior (AddToStart, AddToEnd, Ignore)
FeedQuery.kt	Adds the onNewActivity callback parameter with default implementation
OnNewActivityDefault.kt	Implements the default behavior: add to start only for current user's activities that match the filter
FeedEventHandler.kt	Invokes the onNewActivity callback and passes the result to state updates
FeedStateImpl.kt	Handles all three insertion actions when adding new activities
List.kt	Extends upsert function to support prepending elements
TestData.kt	Makes user parameter customizable in test data factory
OnNewActivityDefaultTest.kt	Tests the default callback implementation with various scenarios
FeedEventHandlerTest.kt	Updates tests to verify insertion action handling
FeedStateImplTest.kt	Tests all three insertion actions (Ignore, AddToStart, AddToEnd)

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[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
91.1% Coverage on New Code
0.1% Duplication on New Code

See analysis details on SonarQube Cloud

[gpunto]

I'm not particularly convinced about using this package. Suggestions are welcome

[VelikovPetar]

The InsertionAction is kinda related to state updates, so I think it is fine 🤷‍♂️ Another option would be maybe to introduce a feed package and place it there -> but that would mean that we should re-organise the whole package structure.

[gpunto]

but that would mean that we should re-organise the whole package structure.

😨

The InsertionAction is kinda related to state updates, so I think it is fine

Then let's keep it as it is. I often find it difficult to organize packages, especially when there's just 1 file that seems to not fit well anywhere. 😓