o2buvioma: Autoplay mobile feed videos muted when they snap into view, with a session mute toggle and tap to pause

src/lib/autoplay.ts

@@ -0,0 +1,24 @@
+/**
+ * Mobile feed autoplay: the session's mute choice and how a failed play() is read.
+ * The choice lives in memory only, for this page session: videos start muted
+ * (browsers only autoplay muted video) until the person unmutes one.
+ */
+let sessionMuted = true;
+
+/** True until the person unmutes a video in this session. */
+export function getSessionMuted(): boolean {
+  return sessionMuted;
+}
+
+/** Remember the person's mute choice for the videos that play after this one. */
+export function setSessionMuted(muted: boolean): void {
+  sessionMuted = muted;
+}
+
+/**
+ * True when play() was refused by the browser's autoplay policy. A play() that
+ * was cut short by pause() (AbortError) is not a refusal.
+ */
+export function isAutoplayBlocked(error: unknown): boolean {
+  return !!error && typeof error === "object" && (error as { name?: unknown }).name === "NotAllowedError";
+}