Session-Surface Protocol

The Session-Surface Protocol (SSP) is a draft specification that defines an interaction contract for applications combining natural-language conversation with structured, interactive visual surfaces. Aimed at language-user interfaces, SSP addresses the coordination between conversational sessions and the lifecycle of associated interactive elements, known as surfaces. 1, introduces the concept of the private session surface, focusing on how actions within these surfaces remain valid, expire, refresh, recover, and remain scoped to the authenticated user and session that created them.

SSP is designed for application patterns where chat alone is insufficient but traditional page-based navigation is no longer central. Use cases explicitly mentioned include appointment booking, document approval, commerce, workflow automation, customer support, incident response, data analysis, and agent orchestration. Within SSP, the conversational session is treated as the organizing primitive, and surfaces are structured instruments rendered inside these sessions. These surfaces can display information, collect input, support comparison, request consent, or trigger actions against external systems. The protocol does not specify how surfaces should look or be rendered; instead, it defines their lifecycle, access control, action validity, and recovery from execution failures.

1 is the concept of an action window: any action declared on a surface must be time-bounded. Actions are valid only within this window and must be refreshed if the session's world state changes or if the action expires. The private session surface is strictly scoped—created within a session, accessible only to the authenticated user, and destroyed when the session ends or the surface is retired. These surfaces are not shareable, bookmarkable, citable, or persistent beyond their session, with the protocol intentionally separating private surfaces from future primitives that may address sharing and durability.

SSP is framed as a response to the fragmentation of conversational interfaces, where each vendor creates proprietary approaches to memory, state, tools, and permissions. By proposing shared primitives for session-based interaction, SSP aims to foster interoperability and avoid the pitfalls of fragmented, incompatible systems. The protocol is currently a public draft and not a finalized standard.