Session crashes when connected MCP server restarts

Description

The CLI session crashes/exits when an MCP server it's connected to is restarted, even from a separate terminal.

Steps to reproduce

1. Start a local MCP server (e.g., FastMCP on port 3000)
2. Connect the CLI to it (server shows ListTools/ListResources requests)
3. In a separate terminal, kill and restart the MCP server:

lsof -ti:3000 | xargs kill; sleep 1; nohup uv run my-mcp-server &

1. CLI session crashes immediately

Expected behavior

Should handle MCP server disconnection gracefully — show an error/warning and allow reconnection via /mcp.

Actual behavior

The entire session exits with no error message. The statusline shows the session resume command, suggesting an unclean exit.

Environment

• macOS Darwin 25.2.0
• MCP server: FastMCP 1.6+ (Streamable HTTP transport on port 3000)
• Model: Opus 4.6 (1M context)

Workaround

None found. Even restarting the MCP from a separate terminal crashes the connected session.