RuleProductIndexer
Magento\CatalogRule\Model\Indexer\Rule\RuleProductIndexer
What it does
This indexer updates product prices when catalog price rules are modified.
It identifies which products are affected by rule changes and triggers a reindex of those specific products to ensure pricing reflects the current rule conditions.
Developers interact with this when catalog price rules are saved or deleted, ensuring product prices stay synchronized with active promotional rules.