Pricing on the WhatsApp Business Platform

Official Meta developer documentation describing the WhatsApp Business Platform's conversation-based and per-message pricing model.

Key facts (via search-snippet extraction, 2026-07-29):

• Service messages were free since November 1, 2024. Any free-form reply sent by a business (or a third-party AI tool, not Meta's own AI agent) within the open 24-hour customer service window has incurred no charge.
• Effective October 1, 2026, Meta will begin charging for service messages. Each service message sent in response to a user during the 24-hour customer service window will be billed per message, at the same rate as utility and authentication template messages in that country.
• A related change takes effect August 1, 2026: messages sent via Meta Business Agent will be billed exclusively on a token basis.
• Meta reserves the right to publish the specific October 1, 2026 rates no later than September 1, 2026.

Relevance to the KG. constraint.whatsapp-24h-messaging-window currently describes the 24-hour window purely as a messaging-permission mechanic with no cost dimension ("free-form service messages" implies no charge). This pricing change does not alter the window mechanic itself (still confirmed unchanged as of this run) but adds a new, material cost dimension starting October 1, 2026 that the constraint node does not yet capture. A body update is drafted in evolution-log/2026-07-29/web-refresh.md for the Technical Reviewer rather than applied directly.