Fix a fatal error when the ActivityPub plugin is not active

[akirk]

Without the ActivityPub plugin, /friends/ dies mid-render: the page stops inside the first post's header and nothing after it is sent. Profile pages go the same way.

Feed_Parser_ActivityPub is required only from the friends_load_parsers callback in friends.php, which returns early when \Activitypub\Activitypub doesn't exist — and there is no autoloader. But the templates that render an author's display name call its custom emoji helpers regardless, for every post:

• templates/frontend/parts/header.php, parts/header-status.php — every post in the feed
• templates/frontend/author-header.php — every profile page
• includes/class-frontend.php, includes/class-blocks.php — the author-name blocks

Friends works standalone, so this hits anyone who hasn't installed the ActivityPub plugin, or who deactivates it.

Changes

Rather than scattering class_exists() over five call sites, the display name goes through a filter, which is the gating this plugin already uses for exactly this — two lines below the emoji call, header.php does do_action( 'friends_post_author_meta', $friend_user ), and the ActivityPub parser is what hooks it.

• New friends_author_display_name_html filter, applied wherever an author's display name is rendered, defaulting to esc_html( $display_name ).
• Feed_Parser_ActivityPub::author_display_name_html() hooks it from the constructor, alongside friends_post_author_meta. The parser is only constructed while the ActivityPub plugin is active, so the emoji rendering is added exactly then and the escaped default stands otherwise.

Two other places reached the parser unguarded, and get the gating the rest of their own file already uses:

• templates/frontend/author-header.php — get_actor_acct_from_attributed_to(). A feed can still be marked activitypub in the database with the plugin gone. Returns '' in that case, which is what the helper itself does anyway.
• includes/class-user.php — determine_mastodon_api_user() in mastodon_api_account_id(), which is hooked from the Enable Mastodon Apps integration, so it runs whenever EMA is active, with or without ActivityPub. Its two sibling call sites at :1178 and :1290 were already guarded; this one was missed.
• includes/class-user.php — mastodon_entity_relationship() reads Feed_Parser_ActivityPub::SLUG after its own class_exists() if/else, on a path reached when the class is absent. It compares against the 'activitypub' literal now, the way author-header.php already does.

Everything else that touches the parser is already behind a class_exists/function_exists check: the follower counts in the stats block and widget, direct message delivery status, webfinger resolution, get_activitypub_actor_id(), and the ::SLUG uses across the migrations.

Two references remain formally unguarded and are deliberately left alone, since neither is reachable without the plugin:

• templates/frontend/parts/activitypub/follow-link.php:9 is only ever rendered from Feed_Parser_ActivityPub::friends_post_author_meta().
• includes/class-migration.php:2815 sits downstream of process_potential_reply_post(), which calls \Activitypub\Http::get_remote_object() on its first line.

Testing instructions

Two Playground instances on the same fixture (a subscription with three status posts), one without the ActivityPub plugin and one with it installed and active. A probe mu-plugin reports what is loaded and hooked on a /friends/ request:

	ActivityPub plugin	parser class loaded	friends_author_display_name_html hooked
without	no	no	no — filter returns the escaped default
with	yes	yes	yes

Pages, before and after, without the ActivityPub plugin:

page	before	after
/friends/	15,294 bytes, 1 truncated article	49,542 bytes, 3 articles
/friends/newssite/	13,386 bytes, 0 articles	49,509 bytes, renders

After the change /friends/, /friends/newssite/, /friends/messages/, /friends/followers/ and the Friends and Settings admin pages all return 200 and close their HTML in both configurations, with no JS errors, and the feed shows 3 articles, 2 link preview cards and the correct author names either way.

php -l and phpcs --standard=phpcs.xml clean on all 7 touched files. PHPUnit was not run locally (no WordPress test library on this machine) — leaving that to CI. No test touches the changed code paths directly; the emoji helpers themselves are unchanged and their existing tests still call them as before.

Changelog entry

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Changelog Entry Details

Type

• Fixed - for any bug fixes

Message

Fix a fatal error that stopped the friends page from rendering when the ActivityPub plugin is not active.

https://claude.ai/code/session_01J7aozaEFaZ3vLaLXith1qm