Default sandbox exec commands to Bash (#764)

Co-authored-by: Ahmed Allam <ahmed39652003@gmail.com>

strix/agents/factory.py

@@ -209,6 +209,13 @@ def _wrap_exec_command(tool: FunctionTool) -> FunctionTool:
     invoke_tool = tool.on_invoke_tool
 
     async def invoke(ctx: Any, raw_input: str) -> Any:
+        try:
+            parsed = json.loads(raw_input)
+        except (json.JSONDecodeError, TypeError):
+            parsed = None
+        if isinstance(parsed, dict) and "shell" not in parsed:
+            parsed["shell"] = "bash"
+            raw_input = json.dumps(parsed)
         try:
             return await invoke_tool(ctx, raw_input)
         except ValidationError as exc: