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Published: February 4, 2026 The Session Config Options RFD has moved to Completed and is stabilized. Session Config Options give agents a flexible way to expose session-level configuration such as models, modes, reasoning levels, and other selectors. Instead of hard-coding a small set of protocol-level controls, clients can render the options an agent provides and keep them in sync as they change. The stable protocol documentation is available in Session Config Options, and the design history remains in the Session Config Options RFD.