Documentation Index

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Session Usage Updates are stabilized

Announcement that session context and cumulative cost updates are now part of the stable ACP protocol.

Published: June 5, 2026

The Session Context Size and Cost RFD has moved to Completed and usage_update session notifications are stabilized.

Agents can report the current context token count and context-window size, along with optional cumulative session cost. This lets Clients keep context and cost displays current throughout the session lifecycle.

For the protocol documentation, see Session Usage Updates.

Last updated Oct 08, 2026