Read MCP SSE responses incrementally instead of to end-of-stream - #3
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The legacy Streamable HTTP / HTTP+SSE transports answer a POST on a text/event-stream that the server may hold open — the Azure Functions MCP extension does exactly this, and also mints an Mcp-Session-Id. parseMCPResponse read that body with response.text(), which only resolves when the stream closes, so the scan hung against such servers and reported them as unreachable. Read the stream via a reader and resolve on the first SSE event carrying a JSON-RPC payload, then cancel the reader to close the connection. Reassemble events split across chunks, skip keepalive/comment frames, and handle CRLF; fall back to buffering when response.body is unavailable. Add tests covering incremental parsing (including a held-open stream that must not block) and an end-to-end connect against a legacy SSE server with a session id, asserting era detection and that the minted Mcp-Session-Id is echoed on the initialized notification. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01N4mJKbHLw7YzjnfHJjtWn5
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The legacy Streamable HTTP / HTTP+SSE transports answer a POST on a text/event-stream that the server may hold open — the Azure Functions MCP extension does exactly this, and also mints an Mcp-Session-Id. parseMCPResponse read that body with response.text(), which only resolves when the stream closes, so the scan hung against such servers and reported them as unreachable.
Read the stream via a reader and resolve on the first SSE event carrying a JSON-RPC payload, then cancel the reader to close the connection. Reassemble events split across chunks, skip keepalive/comment frames, and handle CRLF; fall back to buffering when response.body is unavailable.
Add tests covering incremental parsing (including a held-open stream that must not block) and an end-to-end connect against a legacy SSE server with a session id, asserting era detection and that the minted Mcp-Session-Id is echoed on the initialized notification.
Claude-Session: https://claude.ai/code/session_01N4mJKbHLw7YzjnfHJjtWn5