Fix fatal error in Stream connector on new follower

[pfefferle]

Proposed changes:

Fixes a fatal error on every inbound Follow for any site running the Stream plugin.

Since 7.5.0, the activitypub_handled_follow hook passes its user IDs as an array (int[]). The Stream integration's callback_activitypub_handled_follow() still treated that argument as a scalar and forwarded the array straight into WP_Stream\Connector::log()'s $user_id parameter. Stream then built a WP_User from the array:

PHP Fatal error: Uncaught TypeError: trim(): Argument #1 ($string) must be of type string, array given
  …/class-wp-user.php(160): WP_User::get_data_by('login', Array)
  …/stream/classes/class-log.php(78): WP_User->__construct(0)
  …/activitypub/integration/stream/class-connector.php(122): WP_Stream\Connector->log(…, Array)
  …/activitypub/includes/handler/class-follow.php(83): do_action('activitypub_handled_follow', …)

The fix normalizes the user IDs to a single integer in the callback (\is_array( $user_ids ) ? \reset( $user_ids ) : $user_ids), mirroring the pattern already used by every other consumer of this hook (Follow::queue_accept, Mailer::new_follower, Event_Stream::signal_inbox). I audited all consumers of the (array) $user_ids hooks — the Stream follow callback was the only one mishandling the array.

Other information:

• Have you written new tests for your changes, if applicable? (Updated the Stream connector tests to pass the array the hook actually emits; they fail without the fix.)

Testing instructions:

• With the Stream plugin active, have a remote account follow your site (or fire do_action( 'activitypub_handled_follow', $activity, array( 1 ), true, $remote_actor )).
• Before this change: a fatal TypeError in class-wp-user.php. After: the follow is logged to Stream as "New Follower" with no error.
• npm run env-test -- --filter='Follow|Stream' → all green.

Changelog entry

A changelog entry is already included in this PR (.github/changelog/fix-stream-follower-fatal, patch / fixed), so the automatic entry box is left unchecked.

[pfefferle]

This likely resolves the user report at https://wordpress.org/support/topic/follow-activity-reverts-from-unfollow-to-confirm-request/.

Why the symptom matches: the TypeError here is uncaught, so the inbox POST returns HTTP 500. The remote server never receives a clean response for the Follow, so the Accept handshake never completes and the follow button reverts from "Unfollow" back to "Confirm request." Production logs from an affected (Stream-active) site show this exact fatal firing on activitypub_handled_follow.

Caveat: this only explains the report if the affected site has the Stream plugin active — the fatal originates in the Stream connector. Sites without Stream would need a different explanation.

[Copilot]

Pull request overview

This PR fixes a fatal error in the Stream integration when handling inbound Follow activities by aligning the Stream connector with the activitypub_handled_follow hook’s current signature (user IDs passed as an int[] since 7.5.0).

Changes:

• Update Stream connector follow callback to normalize the hook’s user IDs argument before logging.
• Adjust Stream connector integration tests to pass the array form the hook actually emits.
• Add a patch-level changelogger entry documenting the fix.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
integration/stream/class-connector.php	Normalizes user_ids for Stream logging to avoid passing an array into Stream’s user resolution.
tests/phpunit/tests/integration/class-test-stream-connector.php	Updates tests to call the callback with int[] and asserts Stream receives a scalar user ID.
.github/changelog/fix-stream-follower-fatal	Adds a patch/fixed changelog entry for the Stream follower fatal error.

[pfefferle]

Thanks @copilot — both addressed in 260fa27:

1. Docblock — corrected: the third argument is the boolean $success flag, and $context is \WP_Post|\WP_Error (the callback already guards with is_wp_error()), not \WP_Post|null.
2. Integer coercion — the resolved user ID is now cast to int, so Stream's log() (which constructs a WP_User) always receives a scalar even if the user IDs array is unexpectedly empty.

CI is green across PHP 7.4 / 8.3 / 8.5.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.