Support stateless MCP-over-ACP #189

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1. PsiACE

   added

   enhancementNew feature or requestNew feature or request

   on Nov 9, 2026
2. frostming commented on Nov 9, 2026

   

   frostming

   on Nov 9, 2026

   Contributor

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   What is the status of the eco-system now? Does Lody or T3 Code support the new MCP-over-ACP?
3. xelandernt commented on Nov 11, 2026

   

   xelandernt

   on Nov 11, 2026

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   I looked at your most popular dependents by github stars + t3 and Lody:

   #	Repo (stars)	Dependent?	MCP over ACP	Old MCP standard	New MCP standard (2026-07-28)
   1	NousResearch/hermes-agent (262,614)	yes	❌ Agent-side only: the ACP adapter accepts mcpServers and connects itself (_mcp_server_config handles stdio/http/sse only)	✅	✅ Explicit protocol=auto/stateless/legacy; server/discover fallback, detects "stateless-only" servers whose initialize is rejected (tools/mcp_tool_transport.py)
   2	bytedance/deer-flow (85,247)	yes	❌ ACP client: builds mcpServers for session/new	✅ ClientSession.initialize() in its session pool	❌
   3	pingdotgg/t3code (56,466)	no — uses @agentclientprotocol/sdk	✅ Yes — old binding only: AcpMcpOverAcpBridge implements mcp/connect → connectionId, mcp/message, notification, mcp/disconnect; also exposes the agent-side client methods. Proxies to HTTP MCP with mcp-session-id + mcp-protocol-version	✅ initialize-based negotiation per connection	❌ no server/discover, no request-scoped path
   4	onyx-dot-app/onyx (33,335)	yes	❌ Drives OpenCode over ACP; MCP is configured as remote HTTP entries in OpenCode config	✅ pinned mcp==1.30.0, FastMCP 3.4, initialize	❌
   5	langchain-ai/deepagents (31,201)	yes	❌ ACP server explicitly types MCP servers as (HttpMcpServer, SseMcpServer, McpServerStdio) — no ACP transport	✅ via langchain-mcp-adapters/FastMCP	❌
   6	jaegertracing/jaeger (23,398)	yes (entry looks stale)	❌ ACP client in Go (jaegerai dials goose); no python dependency left in tree	✅ legacy initialize still answered (statelessly)	✅ mcp.NewStreamableHTTPHandler(..., Stateless: true) — "revision 2026-07-28, no sessions", GET/DELETE answered 405
   7	pydantic/pydantic-ai (21,137)	yes	❌ ACP server hands mcp_servers to a user session_config; its type union includes AcpMcpServer but nothing handles it	✅	✅ "modern session" support (SEP-2575): no handshake, no logging/setLevel, no server→client requests; warns instead of failing
   8	a2ui-project/a2ui (17,059)	yes (transitive)	❌ dependency is transitive: inspect-ai → agent-client-protocol (eval only)	⚠️ Partial: MCP catalog (callMcpTool) + MCP Apps renderer; executes tools through a host-supplied client, ships no transport	❌
   9	MervinPraison/PraisonAI (9,333)	yes	❌ ACP server rejects all mcpServers ("not supported yet"), advertises mcpCapabilities: {http: false, sse: false}	✅ own MCP server with initialize / notifications/initialized; client in praisonai_code	❌
   10	mistralai/mistral-vibe (5,366)	yes	❌ AcpMcpServer → ConfigurationError("uses unsupported ACP transport")	✅ stdio + streamable-http, but unconditionally await session.initialize()	❌
   11	ag2ai/ag2 (5,056)	yes	❌ McpCapabilities(http=False, sse=False, acp=False); ACP client only passes HttpMcpServer	✅	✅ Explicit dual-era support ("handshake era up to 2025-11-25" vs "modern era 2026-07-28") in ag2/mcp
   12	LodyAI/Lody (1,683)	no — uses @agentclientprotocol/sdk	❌ Passes mcpServers over session/new; no connectionId / mcp/* handling anywhere	✅ Full MCP host (stdio, SSE, streamable HTTP, OAuth/PKCE, credential relay)	✅ Its MCP HTTP host branches on mcp-protocol-version: 2026-07-28 → modern handler, else per-request stateless streamable HTTP server

   Pinned SDK versions (proxy for schema generation)

   Repo	agent-client-protocol
   onyx-dot-app/onyx	==0.7.1
   bytedance/deer-flow	>=0.4.0
   MervinPraison/PraisonAI	>=0.7.0
   NousResearch/hermes-agent	==0.9.0
   langchain-ai/deepagents	>=0.10.1
   mistralai/mistral-vibe	==0.11.0
   pydantic/pydantic-ai	>=0.11
   ag2ai/ag2	>=0.12.1
   jaegertracing/jaeger	— (Go-only ACP; python entry appears stale)
   a2ui-project/a2ui	— (transitive, via inspect-ai)
   pingdotgg/t3code	— (@agentclientprotocol/sdk)
   LodyAI/Lody	— (@agentclientprotocol/sdk ^1.3.0, catalogs 1.5.1 || 2.0.2 || 2.5.0)