SandboxServerReloadError

Raised when the server sends a 1001 Going Away close frame.

This indicates a server hot-reload, not a true connection failure. The command is still running on the server.

This is a subclass of SandboxConnectionError, so the auto-reconnect logic in CommandHandle catches it along with all other connection errors. The distinction matters for retry strategy: SandboxServerReloadError triggers immediate reconnect (no backoff), while other SandboxConnectionError triggers exponential backoff.

Users typically never see this exception — it's handled internally.