[P1] Add MCP 2026-07-28 adapter, dual-version negotiation, and conformance matrix #15

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opened 2026-08-12 01:19:33 +00:00 by lost-rob0t · 0 comments

lost-rob0t commented

2026-08-12 01:19:33 +00:00

(Migrated from github.com)

Goal

Maximize MCP interoperability across the legacy sessionful protocol and the new stateless protocol.

Scope

implement MCP 2026-07-28 stateless request encoding/decoding;
implement server/discover support and per-request protocol/client/capability metadata;
support new routing/version metadata required by the 2026 protocol;
implement endpoint compatibility cache with invalidation;
prefer 2026-07-28 when explicit mutual support is known;
fall back to 2025-11-25 when necessary;
handle unsupported-version responses and bounded retry with a mutually supported version;
add old-only/new-only/dual client/server fixtures and integration matrix;
keep direct provider APIs as the model-inference path rather than relying on deprecated MCP Sampling.

Acceptance criteria

client works with 2025-only, 2026-only, and dual-version servers;
server works with 2025-only, 2026-only, and dual-version clients;
dual peers prefer 2026;
selected version and transport are recorded in trace metadata;
protocol fallback never leaks version branching into agent/graph code;
conformance tests exercise negotiation, fallback, stale-cache invalidation, and unsupported-version retry.

Dependencies

#14
parent #3

Research

See RLM-RESEARCH-006-mcp-dual-version-runtime.org.

## Goal Maximize MCP interoperability across the legacy sessionful protocol and the new stateless protocol. ## Scope - implement MCP 2026-07-28 stateless request encoding/decoding; - implement `server/discover` support and per-request protocol/client/capability metadata; - support new routing/version metadata required by the 2026 protocol; - implement endpoint compatibility cache with invalidation; - prefer 2026-07-28 when explicit mutual support is known; - fall back to 2025-11-25 when necessary; - handle unsupported-version responses and bounded retry with a mutually supported version; - add old-only/new-only/dual client/server fixtures and integration matrix; - keep direct provider APIs as the model-inference path rather than relying on deprecated MCP Sampling. ## Acceptance criteria - client works with 2025-only, 2026-only, and dual-version servers; - server works with 2025-only, 2026-only, and dual-version clients; - dual peers prefer 2026; - selected version and transport are recorded in trace metadata; - protocol fallback never leaks version branching into agent/graph code; - conformance tests exercise negotiation, fallback, stale-cache invalidation, and unsupported-version retry. ## Dependencies - #14 - parent #3 ## Research See `RLM-RESEARCH-006-mcp-dual-version-runtime.org`.