feat(core): support 2026 Stateless MCP, array-based auto-negotiation, and HTTP transport routing - #412
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…pecs (#394) * test: Integration test dual-server support * feat(core): update protocol definitions to use MCP_LATEST for draft specs
anubhav756
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July 22, 2026 06:30
anubhav756
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anubhav756
… and HTTP transport routing
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Jul 23, 2026
This was referenced Jul 23, 2026
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Overview
This base branch PR consolidates the 2026 MCP protocol spec upgrades and auto-negotiation feature set into
main. It introduces full support for stateless MCP (SEP-2575), HTTP Transport Routing Headers (SEP-2243), Array-Based Protocol Auto-Negotiation with cascading multi-step fallback, and updates the test harness for dual-server E2E testing.Merging this combined branch enables seamless backward compatibility between modern client SDKs and legacy stateful (
pre-2026) or new stateless (v1.6.0+) servers without lock-step release requirements.Changes
This base PR aggregates 5 feature branch PRs:
#393 — Stateless MCP & Reference Support (SEP-2575)
v20260618protocol transport for stateless communication.DRAFT-2026-v1) and support for JSON schema$refresolution and error utilities.#395 — HTTP Transport Routing Headers (SEP-2243)
v20260618protocol to ensure proper routing across network proxies and middleware.#394 — Protocol Definitions & Lavel Alignment
MCP_DRAFTto active draft specifications.-32004).#402 — Array-Based Protocol Auto-Negotiation & Multi-Step Fallback
Protocol[]) toToolboxClient.ToolboxClient.#executeWithFallbackto prevent application crashes during sequential version downgrades.ProtocolNegotiationErrorfor automatic client-side renegotiation.#413 — Dual-Server Integration & E2E Test Suite
Note
This PR is analogous to Python SDK's googleapis/mcp-toolbox-sdk-python#699.