fix(mcp): handle Streamable HTTP MCP responses with SSE framing#779
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Mohl wants to merge 1 commit intoRightNow-AI:mainfrom
Open
fix(mcp): handle Streamable HTTP MCP responses with SSE framing#779Mohl wants to merge 1 commit intoRightNow-AI:mainfrom
Mohl wants to merge 1 commit intoRightNow-AI:mainfrom
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MCP servers using Streamable HTTP (e.g., Hindsight) wrap JSON-RPC
responses in SSE framing (event: message\ndata: {...}\n\n). The SSE
transport handler expected raw JSON, causing 'Invalid MCP SSE JSON-RPC
response' errors when connecting to these servers.
Extract the JSON payload from SSE data: lines before deserializing.
Falls back to raw body parsing for servers that return plain JSON.
Fixes connection to MCP servers implementing the Streamable HTTP
transport (MCP spec 2025-03-26).
Author
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Note: This change was necessary to get openfang to work with hindsight mcp server. |
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Problem
MCP servers using Streamable HTTP transport (e.g., Hindsight) wrap JSON-RPC responses in SSE framing:
The SSE transport handler expected raw JSON bodies, causing
Invalid MCP SSE JSON-RPC response: expected value at line 1 column 1errors when connecting to these servers.Fix
Extract the JSON payload from
data:lines before deserializing. Falls back to raw body parsing for servers that return plain JSON, so existing SSE servers are unaffected.Testing
Context
Streamable HTTP is the newer MCP transport defined in the MCP spec (2025-03-26). This change adds forward-compatible support without requiring a new transport type.