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Experimental. Sponsored Intelligence (si_get_offering, si_initiate_session, si_send_message, si_terminate_session) is part of AdCP 3.0 as an experimental surface — it may change between 3.x releases with at least 6 weeks’ notice. Sellers implementing any of these tasks MUST declare sponsored_intelligence.core in experimental_features. See experimental status for the full contract.
The Sponsored Intelligence Protocol defines four tasks for managing conversational brand experiences:

Session Lifecycle

Two Entry Points

With pre-session lookup (dotted line): Host calls si_get_offering first to show products before consent. The offering_token carries what was shown into the session. Direct session (solid line): Host calls si_initiate_session directly. Brand agent shows products as part of the conversation and tracks them internally. Both are valid. Use pre-session lookup for sponsored search results where you want to preview products before asking the user to engage.

Tasks

TaskDescriptionInitiator
si_get_offeringGet offering details, availability, and matching products (anonymous)Host
si_initiate_sessionStart a conversation with a brand agentHost
si_send_messageExchange messages within an active sessionHost
si_terminate_sessionEnd the session with appropriate handoffEither

Transport Options

SI tasks work over both MCP and A2A protocols:

MCP Transport

A2A Transport

Common Patterns

Minimal Session (No Identity)

For anonymous browsing without personalization:

Full Identity Session

For personalized experiences with consented PII:

Campaign-Triggered Session

When SI is invoked as part of a media buy: