Plugin MCP tools hang indefinitely with no timeout or error

Bug Report

Version: 2.1.89

Description:
Plugin-based MCP tools (e.g. mcp__linear__*) hang for ~2 minutes with no response, no timeout, no error message, and no permission prompt — even when the tool pattern is explicitly in the allow list in settings.json.

Steps to reproduce:

1. Enable a Claude plugin (e.g. Linear via enabledPlugins in settings.json)
2. Add mcp__linear__* to the permissions.allow list
3. Call any Linear MCP tool (e.g. linear_search_issues)
4. Tool hangs for ~2 minutes then times out silently

Expected behavior:
Tool either executes successfully or returns a clear error/auth prompt.

Actual behavior:
Silent hang. No timeout message, no auth prompt, no error in debug logs. Debug logs show no MCP activity during the hang.

Workaround:
Using a local MCP server via mcp.json with an API key works, but plugin-based tools do not.

Platform: macOS Darwin 25.4.0