v1.7.0-pre.3

This is a follow-up pre-release on top of v1.7.0-pre.2, still targeting protocol version 2026-07-28. It rounds out the previous pre-release with additional spec-compliance fixes, small ergonomic improvements to the streamable HTTP transport, and OAuth session persistence support.

Streamable HTTP request cancellation

The streamable HTTP transport now exposes an opt-in StreamableHTTPOptions.PropagateRequestCancellation flag. When enabled, aborting an in-flight POST cancels the handler context on stateless servers using the 2026-07-28 protocol, so long-running tool handlers can stop paying for orphaned work when the client goes away. Existing behavior is unchanged by default.

• mcp: allow opt-in to cancel handler ctx on aborted POST by @guglielmo-san (#1099)

OAuth session persistence

Adds NewTokenSource and InitialTokenSource fields to AuthorizationCodeHandlerConfig. Together they let applications persist OAuth2 sessions across restarts by intercepting token refreshes and seeding the handler with a previously saved token source. A package example demonstrates the persistence pattern.

• auth: support OAuth2 session persistence by @smlx (#1058)

Spec compliance fixes

Continued alignment with the spec adjustments for the 2026-07-28 protocol.

• mcp: update return meta in DiscoverResult (SEP-2575) by @guglielmo-san (#1097)
• mcp: add return type to subscriptions/listen by @guglielmo-san (#1088)
• mcp: reject calls to server/discover for <2026-07-28 requests by @guglielmo-san (#1084)
• mcp: include resultType on new-protocol responses by @ychampion (#1060)
• mcp: infer elicit mode from ElicitParams by @guglielmo-san (#1078)
• mcp: wrap unmarshalParams errors with a JSON-RPC error by @guglielmo-san (#1087)
• mcp: add param validation for CompleteResult by @guglielmo-san (#1080)
• mcp: do not ApplyDefault when res.Content == nil by @guglielmo-san (#1069)

Behavior changes guarded by MCPGODEBUG

Two new escape-hatch flags are added in this pre-release to restore the previous behavior of two spec-compliance fixes above.

• nowrapinvalidparams=1 — restore the previous behavior of returning raw unmarshalParams errors from receiving handlers instead of wrapping them as a JSON-RPC -32602 Invalid params error. Introduced by #1087.
• disablecompleteparamsvalidation=1 — restore the previous behavior of accepting completion/complete responses without validating the presence of the completion params object. Introduced by #1080.

Other Changes to the SDK

• docs: update docs by @guglielmo-san (#1089)
• docs: update troubleshoot.md to include resultType by @guglielmo-san (#1081)
• ci: fix nightly runs by @guglielmo-san (#1086)

New Contributors

• @ychampion made their first contribution in #1060

Full Changelog: v1.7.0-pre.2...v1.7.0-pre.3