1x response to a request with a query

A client sends a request whose URI is gemini://example.com/search?foo and gets a 1x response. If the user types bar, which request should the client send?

1. gemini://example.com/search?bar (overwrite)

2. gemini://example.com/search?foo&bar (append)

If 2, should the client use & as shown, or %09 (tab), or &q=, or something else?

I favor 2 and %09.