fix(qq): add configurable message format and onboard backfill

nanobot/cli/commands.py

@@ -6,6 +6,7 @@ import select
 import signal
 import sys
 from pathlib import Path
+from typing import Any
 
 # Force UTF-8 encoding for Windows console
 if sys.platform == "win32":
@@ -259,6 +260,20 @@ def onboard():
     console.print("\n[dim]Want Telegram/WhatsApp? See: https://github.com/HKUDS/nanobot#-chat-apps[/dim]")
 
 
+def _merge_missing_defaults(existing: Any, defaults: Any) -> Any:
+    """Recursively fill in missing values from defaults without overwriting user config."""
+    if not isinstance(existing, dict) or not isinstance(defaults, dict):
+        return existing
+
+    merged = dict(existing)
+    for key, value in defaults.items():
+        if key not in merged:
+            merged[key] = value
+        else:
+            merged[key] = _merge_missing_defaults(merged[key], value)
+    return merged
+
+
 def _onboard_plugins(config_path: Path) -> None:
     """Inject default config for all discovered channels (built-in + plugins)."""
     import json
@@ -276,6 +291,8 @@ def _onboard_plugins(config_path: Path) -> None:
     for name, cls in all_channels.items():
         if name not in channels:
             channels[name] = cls.default_config()
+        else:
+            channels[name] = _merge_missing_defaults(channels[name], cls.default_config())
 
     with open(config_path, "w", encoding="utf-8") as f:
         json.dump(data, f, indent=2, ensure_ascii=False)