[Bug] The method of invoking plugins via MCP is unavailable

What happened? / 问题描述

When Page Agent is invoked via an MCP client (e.g. Cursor, Claude Desktop) with LLM credentials configured in the MCP server's env block, the task is received by the extension but never actually executes. Instead, the extension enters an infinite loop where the agent is created and disposed repeatedly, and the MCP client keeps retrying with the same error.

How to reproduce / 如何复现

Any MCP config that passes LLM env vars will trigger it, e.g.:

{
    "mcpServers": {
        "page-agent": {
            "command": "npx",
            "args": ["-y", "@page-agent/mcp"],
            "env": {
                "LLM_BASE_URL": "https://dashscope.aliyuncs.com/compatible-mode/v1",
                "LLM_API_KEY": "sk-xxx",
                "LLM_MODEL_NAME": "qwen3.5-plus"
            }
        }
    }
}

Removing the env block (letting the extension use its own settings) makes the bug disappear. Invoking the MCP server manually via npx @modelcontextprotocol/inspector without passing config also works fine — which confirms the trigger is the config payload from env.

Version

1.12.1

Browser

chrome 148.0.7778.217（正式版本） （64 位）

Before submitting

• I will be polite and respectful. / 我会保持礼貌与尊重。
• I have read the Code of Conduct. / 我已阅读行为准则。
• I have searched existing issues and this is not a duplicate.