Silence a free video once its sprite is destroyed (#420)

A sprite whose Video clock is free played its video on after it was
destroyed, heard in a game, until the player was let go 2 to 4 s
later. A driven one was already held and quiet after 100 ms.

- The library holds and quiets a free player nothing asked for in
  HUSH_MS, as it did a driven one. That covers Destroy, a scene load,
  the end of a run and a sprite switched off.
- Asked for again before it is let go, it plays on from where it was
  held, heard only in a run. A hidden page leaves it alone, as the
  sweep does.
- A sprite only out of view keeps its free video playing and heard.
  Whether a video is heard should not hang on the camera. Before, it
  ran 2 to 4 s and was then let go. Now it plays on, which opens its
  player even where it was never in view.

Tests:
- Unit: video-library 1 new. A free player losing its wearer is held
  and quiet 200 ms later, stays so through a new run, plays on heard
  when asked again with the same element, and runs on on a hidden
  page.
- e2e 66 on melektaus-atx: ALL PASSED, 36 checks, 66g-ii new. Heard
  31 frames before Destroy, held and muted in every frame read after.
- Counter-probe without hushing free players: the unit test and only
  66g-ii fail, the player plays on heard (paused false, muted false).
- Gate on melektaus-atx: 309 files, 4797 tests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/viewport/VideoLibrary.ts

@@ -39,9 +39,9 @@ const END_SLACK = 1 / 60;
 /** A player nothing has asked for in this long is let go: no sprite wears it any more. */
 const IDLE_MS = 2000;
 /**
- * A driven player (#404) nothing has asked for in this long is held and quiet: its wearer is gone,
- * like the sprite of a composition item that has ended, or no longer drawn. It runs on by itself
- * otherwise, heard, until it is let go.
+ * A player nothing has asked for in this long is held and quiet: its wearer is gone, like a sprite
+ * destroyed or the sprite of a composition item that has ended, or no longer drawn. It runs on by
+ * itself otherwise, heard, until it is let go. A free one (#420) plays on from there once asked again.
  */
 const HUSH_MS = 100;
 /** Seconds a driven video's level takes to get most of the way to a new one, see `hear`. */
@@ -90,6 +90,8 @@ interface Player {
   asked: number;
   /** Set when its wearer sets the time rather than the video itself. */
   drive: Drive | null;
+  /** Whether a free player is held and quiet because nothing wears it, see `hush`. */
+  hushed: boolean;
 }
 
 export class VideoLibrary {
@@ -120,6 +122,7 @@ export class VideoLibrary {
     const player = this.players.get(key) ?? this.start(key);
     if (!player) return null;
     player.asked = performance.now();
+    if (player.hushed) this.unhush(player);
     return player.texture;
   }
 
@@ -170,12 +173,15 @@ export class VideoLibrary {
     return false;
   }
 
-  /** A run begins: every player from its start, heard. A driven one goes where its wearer says. */
+  /**
+   * A run begins: every player from its start, heard; a hushed one once it is worn again. A driven
+   * one goes where its wearer says.
+   */
   startRun(): void {
     this.heard = true;
     this.paused = false;
     for (const player of this.freePlayers()) {
-      this.hear(player);
+      if (!player.hushed) this.hear(player);
       this.rewind(player);
     }
   }
@@ -194,7 +200,7 @@ export class VideoLibrary {
     this.paused = paused;
     for (const player of this.freePlayers())
       if (paused) player.element.pause();
-      else void player.element.play().catch(() => {});
+      else if (!player.hushed) void player.element.play().catch(() => {});
   }
 
   private freePlayers(): Player[] {
@@ -246,18 +252,30 @@ export class VideoLibrary {
   }
 
   /**
-   * Holds and quiets the driven players nobody asked for lately, see `HUSH_MS`. One still without
-   * its first picture plays on, without sound: it only gets one by playing (see `openVideo`).
+   * Holds and quiets the players nobody asked for lately, see `HUSH_MS`. One still without its first
+   * picture plays on, without sound: it only gets one by playing (see `openVideo`). A free one is
+   * left alone while the page is hidden, as by `sweep`.
    */
   private hush(): void {
     const now = performance.now();
     for (const player of this.players.values()) {
-      if (!player.drive || !player.texture || now - player.asked <= HUSH_MS) continue;
+      if (player.drive) {
+        if (!player.texture || now - player.asked <= HUSH_MS) continue;
+      } else if (player.hushed || document.hidden || now - Math.max(player.asked, this.shown) <= HUSH_MS)
+        continue;
+      player.hushed = !player.drive;
       player.element.muted = true;
-      if (!player.element.paused) player.element.pause();
+      if (player.texture && !player.element.paused) player.element.pause();
     }
   }
 
+  /** A free player worn again plays on from where it was held, heard in a run. */
+  private unhush(player: Player): void {
+    player.hushed = false;
+    if (this.heard) this.hear(player);
+    if (!this.paused) void player.element.play().catch(() => {});
+  }
+
   private stopSweeping(): void {
     if (this.sweeper !== null) clearInterval(this.sweeper);
     if (this.husher !== null) clearInterval(this.husher);
@@ -306,8 +324,8 @@ export class VideoLibrary {
         if (player.gone) return texture.destroy(true);
         player.texture = texture;
         if (drive) this.follow(player, drive);
-        // Started even in a paused run, and held once there is a picture.
-        else if (this.paused) player.element.pause();
+        // Started even in a paused run or when nothing wears it, and held once there is a picture.
+        else if (this.paused || player.hushed) player.element.pause();
         this.notify();
       }),
       texture: null,
@@ -316,10 +334,11 @@ export class VideoLibrary {
       gone: false,
       asked: performance.now(),
       drive,
+      hushed: false,
     };
     this.players.set(key, player);
     this.sweeper ??= setInterval(() => this.sweep(), IDLE_MS);
-    if (drive) this.husher ??= setInterval(() => this.hush(), HUSH_MS);
+    this.husher ??= setInterval(() => this.hush(), HUSH_MS);
     if (drive)
       chaseSeeks(
         player.element,
@@ -376,7 +395,7 @@ export class VideoLibrary {
 
   private rewind(player: Player): void {
     player.element.currentTime = player.play.start;
-    if (!this.paused) void player.element.play().catch(() => {});
+    if (!this.paused && !player.hushed) void player.element.play().catch(() => {});
   }
 
   private drop(player: Player): void {