Allows WebTransport applications to indicate how many incoming streams they expect to have open at once. Constructor hints configure the initial QUIC stream allowance, reducing the risk that a server that needs high stream concurrency is blocked by the initial stream limit.
Some WebTransport applications expect a server to open many streams at once. If the initial QUIC stream allowance is too low, the server must wait for more stream credit before opening additional streams, adding avoidable latency or limiting the number of open streams. Constructor hints let the application state its expected stream count when creating the connection, so the browser can advertise an appropriate initial allowance. Values above the required minimum are preserved; values below 100 do not reduce the effective allowance because the specification requires clients to initially permit at least 100 streams of each type.
Explainers: https://github.com/w3c/webtransport/issues/544 https://github.com/w3c/webtransport/pull/574