I18N: Fix JIT translations for network-activated plugins in multisite

[sanketio]

Problem

Since WordPress 6.7 (59461), the just-in-time (JIT) translation loading mechanism registers text domains by reading each plugin's Text Domain and Domain Path headers during bootstrap. However, this registration only happened for site-level active plugins (wp_get_active_and_valid_plugins()), completely skipping network-activated plugins (wp_get_active_network_plugins()) in multisite installations.

As a result, PHP translation functions (__(), _e(), etc.) silently fell back to untranslated strings for all network-activated plugins — even when correct translation files were present — because $wp_textdomain_registry had no path registered for those domains and _load_textdomain_just_in_time() had nothing to work with.

Note: JavaScript translations were unaffected as they use a separate mechanism.

Changes

wp-settings.php

• Moves require_once ABSPATH . 'wp-admin/includes/plugin.php' earlier in the bootstrap — from just before the site plugins loop to just before the must-use plugins loop — making get_plugin_data() available for all plugin loading stages. Comment updated to reference both #62244 and #64249.
• Adds text domain registration inside the network-activated plugins loop, mirroring the logic already present in the site plugins loop: reads TextDomain and DomainPath headers via get_plugin_data() and calls $wp_textdomain_registry->set_custom_path() accordingly.
• Adds $plugin_data and $textdomain to the unset() at the end of the network plugins block, consistent with the site plugins loop.

Backward Compatibility

• get_plugin_data() only reads the plugin file's comment header — no database calls, no side effects.
• set_custom_path() is idempotent. Plugins already calling load_plugin_textdomain() explicitly as a workaround will continue to work correctly.
• Moving the require_once earlier carries negligible risk — plugin.php was already hardened for early loading in #62244.

References

• Trac ticket: https://core.trac.wordpress.org/ticket/64249
• Original JIT changeset: https://core.trac.wordpress.org/changeset/59461
• Related ticket: https://core.trac.wordpress.org/ticket/62244

Use of AI Tools

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