How do I select all the pages and articles in the context?

In the free version, you cannot automatically select all pages or posts: training is done in batches of up to 10 items, then each item is activated in Contexts.

With the Premium RAG Auto Sync add-on, you choose which content types are indexed automatically. Newly published content is indexed straight away, and a catch-up button processes existing content without embeddings, up to 25 items per click. Automatic activation in Contexts is optional and off by default. Each indexation uses OpenAI credits.