From 5f4965e7a040a450f361474c59bc1ca11aa7f088 Mon Sep 17 00:00:00 2001
From: Jan-Ivar Bruaroey <jan-ivar@users.noreply.github.com>
Date: Fri, 29 May 2026 20:34:28 -0400
Subject: [PATCH] Set :protocol to webtransport-h3 for WebTransport over HTTP/3

---
 fetch.bs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fetch.bs b/fetch.bs
index 7872b8067..b42163059 100755
--- a/fetch.bs
+++ b/fetch.bs
@@ -6656,6 +6656,13 @@ optional boolean <var>forceNewConnection</var> (default false), run these steps:
    to the <a for=/>coarsened shared current time</a> given <var>fetchParams</var>'s
    <a for="fetch params">cross-origin isolated capability</a>.
 
+   <li>
+    <p>If <var>request</var>'s <a for=request>mode</a> is "<code>webtransport</code>",
+    <var>connection</var> is an HTTP/3 connection, and the "<code>:protocol</code>"
+    pseudo-header associated with <var>request</var>'s <a for=request>method</a> is
+    "<code>webtransport</code>", then set the "<code>:protocol</code>" pseudo-header to
+    "<code>webtransport-h3</code>". [[!WEBTRANSPORT-HTTP3]]
+
    <li>
     <p>Set <var>response</var> to the result of making an HTTP request over <var>connection</var>
     using <var>request</var> with the following caveats: