MCP SDK for Rust 3.2.0

Apply the Rust 1.98 baseline first. These rules cover the official rmcp 3.2.0 SDK, its protocol negotiation, OAuth client, tools and resources, multi-round-trip state, tasks, caching, subscriptions, Streamable HTTP, stdio processes, and deployment.

Version, features, and protocol scope

• Declare rmcp with a caret requirement on the 3.x line and lock it in Cargo.lock. rmcp and rmcp-macros ship together from one workspace but resolve as separate crates, so upgrade them as a pair with cargo update -p rmcp -p rmcp-macros, and review the enabled transports and the release notes on every upgrade.
• Build with a Rust toolchain no older than the SDK's 1.88 minimum, selected by the Rust 1.98 baseline's toolchain rule.
• Set default-features = false and enable only the required role, macros, auth, request-state, and transport features; the default set is base64, macros, and server.
• Select a TLS backend explicitly for HTTPS: auth and transport-streamable-http-client-reqwest enable the reqwest dependency without enabling TLS. Add reqwest, reqwest-native-tls, or reqwest-tls-no-provider with an installed crypto provider as appropriate.
• Do not assume ProtocolVersion::LATEST selects 2026-07-28: in 3.2.0 it remains V_2025_11_25. Select V_2026_07_28 explicitly through the client lifecycle only after testing its stateless HTTP, subscription, header, and multi-round-trip semantics.
• Override ServerHandler::supported_protocol_versions with the revisions the application actually supports; its default advertises every known version from