This article maps WPEstate Translate for developers: where the code lives, what runs at boot, what is stored in the database, and where to hook in. The plugin folder is wpestate-translate and the text domain is wpr-translate. For what the plugin does for site owners, see WPEstate Translate Plugin Overview.

Entry Point and Constants

wpestate-translate.php carries the header (Plugin Name: WPEstate Translate, Version: 1.0.9). It defines the constants, loads the include map and registers the activation and uninstall hooks.

Constant	Value
WPR_TRANSLATE_PLUGIN_ROOT, alias WPR_TRANSLATE_PATH	Plugin folder path, with a trailing slash.
WPR_TRANSLATE_PLUGIN_URL, alias WPR_TRANSLATE_URL	Plugin folder URL, with a trailing slash.
WPR_TRANSLATE_BASENAME	plugin_basename( __FILE__ )
WPR_TRANSLATE_VERSION	Still hard-coded to 0.1.0, not the release number. Read the plugin header when you need the version.

Include Map and Bootstrap

The entry file loads a fixed list, in this order:

includes/activator.php
includes/theme-wpr-locator.php
includes/translation-directories.php
includes/translation-files.php
includes/translation-runtime.php
includes/date-localization.php
includes/custom-field-rules.php
includes/translation-hooks.php
includes/sibling-map.php
includes/language-manager.php
includes/main-lang-functions.php
includes/language-rewrite-bases.php
includes/language-permalinks.php
includes/language-router.php
includes/functions-language.php
includes/functions-permalinks.php
includes/body-language-attribute.php
includes/meta-sync.php
includes/custom-fields-sync.php
includes/theme-widget-strings.php
includes/admin/theme-widget-strings.php
includes/plugin-bootstrap.php

language-manager.php loads the includes/language-context/ modules. plugin-bootstrap.php comes last and loads everything else on every request, admin and front end: the relationship modules, nav menu modules, admin screens, post list and editor, auto-translate, Elementor, the language switcher widget, query filters, SEO tags and compatibility layers.

Activation and Uninstall

wpr_translate_activate_plugin() (activator.php) runs on every activation:

1. Drops the four unused legacy tables (slugs, languages, glossary, memory) and creates the two plugin tables with dbDelta().
2. Adds the wpr_translate_version option.
3. Seeds the language catalog and, if no language exists yet, adds the site locale as the default language.
4. Merges the default settings (sync_media only) and runs the locale migration.
5. Loads the Custom Field Rules from the theme JSON.
6. Stamps an empty _wpr_language (the default language) on existing posts that have none.
7. Calls flush_rewrite_rules().

wpr_translate_uninstall_plugin() deletes only these options: wpr_translate_version, wpr_translate_languages, wpr_translate_language_catalog, wpr_translate_settings, wpr_translate_locale_migration_237, wpr_translate_locale_migration. The tables, post and term meta, and translated content stay. Full details: Installation, Activation and Uninstall.

Where Data Is Stored

Data	Storage
Translation links between posts	Post meta: _wpr_language on every post, _wpr_translations on the source, wpr_translated_original_post_id and wpr_translated_language on each translation.
Translation links between terms	Term meta: wpr_term_language, wpr_translated_term_{lang} on the source, wpr_original_term_id on each translation.
Theme and plugin string translations	Table {prefix}wpestate_translation_strings, exported to .mo files by Generate translation files.
Links made by older versions	Table {prefix}wpestate_translation_translations (the trid table). It is read as a fallback when an object has no link meta. Nothing writes new rows.
Languages, settings, rules	Options, see below.

Read links through the relationship API (wpr_translate_relationship_get_post_family(), wpr_translate_relationship_resolve_post() and the term versions), not by querying meta or the table directly. See Translation Linking and Database Schema Reference.

Options

Option	Content
wpr_translate_languages	Configured languages (code, locale, name, slug, flag, is_default, is_active, is_public, formats). The default language is the entry with is_default.
wpr_translate_language_catalog	The predefined language catalog.
wpr_translate_settings	url_strategy (always subdirectory), sync_media, elementor_compatibility, taxonomy_modes, taxonomy_auto_duplicate, menu_language_switcher. There is no default language key: the sanitizer removes default_language.
wpr_translate_auto_translation	Translation provider settings and API keys.
wpr_cf_rules_defaults, wpr_cf_rule_overrides, wpr_cf_file_state	Custom Field Rules: defaults from the theme JSON, overrides from the admin screen.
wpr_translate_version	Written on activation.

wpr_translate_admin_register_settings() in includes/admin/menu.php registers wpr_translate_languages, wpr_translate_settings and wpr_translate_auto_translation.

Admin Menu

wpr_translate_admin_register_menus() adds the top-level WPEstate Translate menu (slug wpr-translate-overview, capability manage_options) with these submenus:

Slug	Label
wpr-translate-overview	Start Here
wpr-translate-languages	Languages
wpr-translate-strings	Theme & Plugins Strings
wpr-translate-taxonomies	Taxonomy Translation
wpr-translate-custom-fields	Custom Field Rules
wpr-translate-automatic-translation	Automatic Translation
wpr-translate-menu-sync	Menu Synchronization
wpr-translate-settings	Settings

The views are in includes/admin/views/.

Subsystems

Subsystem	Primary files
Languages and catalog	language-manager*.php, language-context/*.php, language-catalog.php, main-lang-functions.php, functions-language.php
URL routing and permalinks	language-router.php, language-permalinks.php, language-rewrite-bases.php, permalinks-helpers.php, functions-permalinks.php, body-language-attribute.php
Translation links	translation-relationships*.php, sibling-map.php
Query language filter	query-filter.php, query-filter-helpers.php, translation-taxonomies.php
Meta and custom field sync	meta-sync.php, custom-fields-sync.php, custom-field-rules*.php
SEO and hreflang	seo-tags.php, seo-tags-helpers.php
Elementor and shortcodes	elementor-widget-compat.php, shortcode-compat.php, adv6-terms-compat.php, admin/elementor-*.php
Nav menus	nav-menu-*.php, admin/nav-menus*.php
Post list and editor	admin/post-list-*.php, admin/post-editor.php, admin/editor-header-language.php
String translation	translation-runtime.php, translation-files.php, string-catalog*.php, admin/string-*.php
Automatic translation	admin/auto-translate-*.php, admin/translation-request.php
Maintenance	admin/cache-purge.php, admin/delete-translations.php, admin/reset-settings.php

Extension Points

Hook	Where	Use
wpr_current_language	functions-language.php	Filter that returns the current language code.
wpr_object_id	functions-language.php	Filter that returns the translated ID of an object.
wpr_translate_language_router_skip_detection, wpr_translate_language_router_skip_prepare, wpr_translate_language_router_force_prepare	language-router.php	Control language detection and request preparation for special routes.
wpr_translate_should_sync_post_meta, wpr_translate_meta_field_behaviors	meta-sync.php	Skip meta sync or change field behaviors.
wpr_translate_custom_field_rules_file, wpr_translation_custom_field_rule, wpr_translation_custom_field_preferences	custom-field-rules.php, admin/post-list-meta.php	Change the rules file or single rules.
wpr_translate_runtime_translation	translation-runtime.php	Change a string translation at runtime.
wpr_translate_custom_translations_directory, wpr_translate_custom_translations_directory_candidates	translation-directories.php	Change where translation files are loaded from.
wpr_translate_auto_translation_excluded_post_types	admin/settings-helpers.php	Exclude post types from automatic translation.
wpr_translate_strings_per_page	admin/string-query.php	Rows per page on the strings screen.

1.0.9 fires no action when a translation is linked. The old wpr_translation_created action sits in a legacy writer that nothing calls. To react to new links, watch added_post_meta and updated_post_meta for _wpr_translations.

Gotchas

• The language comes from the URL prefix only. There is no cookie or browser-language detection. See Language Detection and Redirects.
• The default language is the is_default flag in wpr_translate_languages, set on the Languages screen.
• Uninstall keeps both tables. Reset Translation Settings truncates both tables, deletes the plugin options (including API keys and Custom Field Rules overrides) and runs activation again. Translated posts and terms stay.
• Activation merges settings with wp_parse_args(), so existing values survive reactivation.
• Queries with suppress_filters are not language-filtered. See WP_Query Language Filtering.

More: Gettext Pipeline and MO Files.