fix: redirect console logging to stderr for MCP stdio transport#6
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Jasper-1222 wants to merge 1 commit into
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fix: redirect console logging to stderr for MCP stdio transport#6Jasper-1222 wants to merge 1 commit into
Jasper-1222 wants to merge 1 commit into
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The setup_logging function configured StreamHandler(sys.stdout), which interleaves log lines with MCP JSON-RPC protocol messages on stdout. This violates the MCP stdio transport specification, which requires uncontaminated stdout for JSON-RPC wire format frames. Changed to sys.stderr so structured logs go to stderr while stdout remains clean for the MCP protocol. This is the Python convention: stdout for program data, stderr for diagnostics. The file handler continues to write to logs/mcp2anp.log as before.
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Summary
修复 stdio 模式下日志输出污染 MCP 协议通道的问题。
现象
启动 mcp2anp stdio 模式后，
list_tools可以正常工作，但call_tool偶尔失败。错误原因是 structlog 的 ConsoleRenderer 将彩色格式的日志行输出到了 stdout，与 MCP JSON-RPC 协议帧混合，导致客户端解析 JSON-RPC 消息失败。根因
setup_logging函数在mcp2anp/utils/logging.py第 33 行配置了StreamHandler(sys.stdout)。MCP stdio 传输协议要求 stdout 只传输 JSON-RPC 协议帧，所有诊断输出必须走 stderr。这是 Python 社区的标准约定。修复
将
StreamHandler(sys.stdout)改为StreamHandler(sys.stderr)。logs/mcp2anp.log（不受影响）Verification
本地测试通过，8/8 MCP bridge tests pass。
Risk
低风险。仅影响日志输出流，不涉及业务逻辑。