fix(ssh): suppress asyncssh info log formatting noise

apps/api/src/plugins/mcp/providers/ssh_provider.py

@@ -41,6 +41,7 @@ SSH 連線:
 @see docs/superpowers/specs/2026-04-10-infra-rebuild-sprint-abc-design.md §MCP-2a
 """
 
+import logging
 import re
 import uuid
 from datetime import UTC, datetime
@@ -51,6 +52,7 @@ import structlog
 from src.plugins.mcp.interfaces import MCPTool, MCPToolProvider, MCPToolResult
 
 logger = structlog.get_logger(__name__)
+_asyncssh_logger_configured = False
 
 # =============================================================================
 # 安全常數
@@ -128,6 +130,22 @@ def _normalize_ssh_host(value: str) -> str:
             return maybe_host
     return host
 
+
+def _quiet_asyncssh_info_logs() -> None:
+    """Keep third-party asyncssh INFO logs from breaking stdlib %-format logging.
+
+    Some target SSH servers send exit status as a string. AsyncSSH then emits an
+    INFO log with ``%d`` and that string argument before our code sees the
+    result, which produces noisy ``TypeError: %d format`` tracebacks. The tool
+    result itself is still available, so production should keep asyncssh at
+    WARNING and rely on our structured MCP audit logs.
+    """
+    global _asyncssh_logger_configured
+    if _asyncssh_logger_configured:
+        return
+    logging.getLogger("asyncssh").setLevel(logging.WARNING)
+    _asyncssh_logger_configured = True
+
 # 群組 A（只讀）
 GROUP_A_TOOLS = {
     "ssh_diagnose",
@@ -630,6 +648,8 @@ class SSHProvider(MCPToolProvider):
                 "Add 'asyncssh' to pyproject.toml dependencies."
             ) from None
 
+        _quiet_asyncssh_info_logs()
+
         import os
         if not os.path.exists(SSH_KEY_PATH):
             raise RuntimeError(