WordPress Site Health provides diagnostic tests and debugging info. Transients offer temporary cached data storage with automatic expiration.

Since: Site Health 5.2.0, Transients 2.8.0
Source:

• wp-admin/includes/class-wp-site-health.php
• wp-admin/includes/class-wp-site-health-auto-updates.php
• wp-includes/rest-api/endpoints/class-wp-rest-site-health-controller.php
• wp-includes/option.php (transient functions)
• wp-includes/class-wp-feed-cache-transient.php

Components

Transients vs Options

Site Health Test Flow

WP_Site_Health::get_tests()
    ├── direct tests (run on page load)
    │   └── get_test_{name}() → result array
    └── async tests (run via REST/AJAX)
        └── WP_REST_Site_Health_Controller
            └── test_{endpoint}() → result array

Test Result Structure

array(
    'label'       => 'Human-readable label',
    'status'      => 'good|recommended|critical',
    'badge'       => array(
        'label' => 'Category',        // Security, Performance, etc.
        'color' => 'blue|orange|red|green|purple|gray',
    ),
    'description' => 'Detailed explanation',
    'actions'     => 'HTML with action links',
    'test'        => 'test_identifier',
)

Transient Storage

Database (no object cache):
    _transient_{name}           → value
    _transient_timeout_{name}   → expiration timestamp

Site Transients (multisite):
    _site_transient_{name}      → value (sitemeta table)

Object Cache (Redis/Memcached):
    transient:{name}            → value with TTL
    site-transient:{name}       → value with TTL