Merge branch 'master' into worktree-mosaic-library

# Conflicts:
#	docs/traceability.md

src/lib/components/player/VideoPlayer.svelte

@@ -120,10 +120,12 @@
    * Keep native's picture-in-picture state in step with the `<video>` element.
    *
    * PiP is driven by the Activity, and it only ever knew about the native
-   * ExoPlayer surface — a path behind `experimentalNativeVideo`, which defaults
-   * to off. So in the shipping configuration nothing satisfied its "is a video
-   * playing?" check and the PiP button did nothing at all. Reporting the element
-   * gives it a surface it can shrink into. (UR-041, DR-160)
+   * ExoPlayer surface — a path behind `experimentalNativeVideo`, which at the
+   * time defaulted to off. So in the then-shipping configuration nothing
+   * satisfied its "is a video playing?" check and the PiP button did nothing at
+   * all. Reporting the element gives it a surface it can shrink into, and still
+   * has to: the flag defaults to on now (DR-161) but a user who turns it off is
+   * back on the element. (UR-041, DR-160, DR-161)
    */
   function reportPipVideoState() {
     if (!useHtml5Element || !videoElement) {