web: force WebTransport-only moq-watch sessions

apps/web/app.js

@@ -161,6 +161,13 @@ function mountPlayer(relayUrl, name) {
   // Support both @moq/watch attribute variants across minor versions.
   watch.setAttribute("name", name);
   watch.setAttribute("path", name);
+  watch.setAttribute("volume", "1");
+
+  // Force WebTransport in-browser; websocket fallback has shown degraded
+  // media behavior (especially audio) against public relay paths.
+  if (watch.connection && typeof watch.connection === "object") {
+    watch.connection.websocket = { enabled: false };
+  }
 
   // A canvas enables video rendering. Without it, only audio is played.
   const canvas = document.createElement("canvas");

evolution/proposals/ECP-0076-webtransport-only-web-watcher.md

@@ -0,0 +1,23 @@
+# ECP-0076: WebTransport-Only Browser Watcher Path
+
+## Context
+
+The browser watcher (`@moq/watch`) races WebTransport against WebSocket fallback by default. In production relay sessions this fallback path correlates with degraded playback behavior (frequent stream resets and unreliable audio despite active subscription).
+
+## Decision
+
+In `apps/web/app.js`, configure each `<moq-watch>` instance to disable WebSocket fallback before connect:
+
+- `watch.connection.websocket = { enabled: false }`
+
+Also set default watcher volume to full (`volume="1"`) to avoid low-volume false negatives during validation.
+
+## Rationale
+
+- Aligns browser transport with the intended relay mode (WebTransport MoQ).
+- Removes fallback-induced variability from live playback behavior.
+- Keeps implementation local to web app wiring without forking upstream packages.
+
+## Reversibility
+
+- Remove the connection override to restore default fallback behavior.