Reset per-game reveal state on new game so reveal animates over cached content

Starting a new game reuses block ids (1,2,3...). The reveal clock's per-block
start times (activeRevealBlockStarts in the lab) and the renderer's animation/
revealed sets are keyed by block id and were never cleared on a client reset, so
a new game over already-cached content inherited the previous run's start times.
beginPageReveal then computed a huge elapsed and the shader treated the reveal as
already complete — showing everything at once instead of animating.

resetClientPlaybackAndDisplay (run on new game and restore) now emits
story:client-reset; the lab clears activeRevealBlockStarts/pending reveal state,
the texture renderer clears active animations and revealed-block ids, and the
timeline invalidates prepared segments. So each game starts with a clean reveal
clock.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/js/book-playback-timeline-module.js

@@ -99,6 +99,10 @@ class BookPlaybackTimelineModule extends BaseModule {
         });
         this.addEventListener(document, 'webgl-book:page-count-changed', this.invalidatePreparedSegments);
         this.addEventListener(document, 'story:history-restoring', this.invalidatePreparedSegments);
+        this.addEventListener(document, 'story:client-reset', () => {
+            this.invalidatePreparedSegments();
+            this.activeSegment = null;
+        });
         window.BookPlaybackTimeline = this;
         this.reportProgress(100, 'Book playback timeline ready');
         return true;

public/js/book-texture-renderer-module.js

@@ -118,6 +118,7 @@ class BookTextureRendererModule extends BaseModule {
         });
         this.addEventListener(document, 'story:manual-scroll', this.fastForwardAnimations);
         this.addEventListener(document, 'story:history-restoring', this.stopAnimations);
+        this.addEventListener(document, 'story:client-reset', this.stopAnimations);
         this.currentSpread = this.pagination?.getCurrentSpread?.() || { index: 0, left: [], right: [], pageMeta: { left: null, right: null } };
         this.drawSpread(this.currentSpread);
         this.reportProgress(100, 'Book texture renderer ready');
@@ -1028,6 +1029,7 @@ class BookTextureRendererModule extends BaseModule {
 
     stopAnimations() {
         this.activeAnimations.clear();
+        this.revealedBlockIds.clear();
         this.drawSpread(this.currentSpread || this.pagination?.getCurrentSpread?.());
     }
 

public/js/game-loop-module.js

@@ -657,6 +657,13 @@ class GameLoopModule extends BaseModule {
         if (inputHandler && typeof inputHandler.clearHistory === 'function') {
             inputHandler.clearHistory();
         }
+
+        // Signal a client reset so transient, block-id-keyed reveal/animation state is
+        // cleared. Without this, a new game that reuses block ids over already-cached
+        // content keeps the previous run's reveal start times and skips the animation.
+        document.dispatchEvent(new CustomEvent('story:client-reset', {
+            detail: { reason: 'client-reset' }
+        }));
     }
 
 }

public/js/webgl-book-lab.js

@@ -695,6 +695,15 @@ document.addEventListener('webgl-book:request-page-flip', (event) => {
 document.addEventListener('webgl-book:page-cache-problem', (event) => {
     pageTextureStore?.recordProblem?.(event.detail || {});
 });
+// New game / history restore: drop block-id-keyed reveal state so a reused block id does
+// not inherit the previous run's reveal start time (which would skip the animation).
+document.addEventListener('story:client-reset', () => {
+    activeRevealBlockStarts.clear();
+    pendingRevealStartBlockIds.clear();
+    pageRevealFreezeAt = null;
+    clearPageReveal('left', 'client-reset');
+    clearPageReveal('right', 'client-reset');
+});
 // Pagination spread updates only carry state. The playback owner decides when the
 // visible spread changes (via flips). The scene jumps directly only for non-playback
 // commits such as history restore. See docs/webgl-3d-ui-spec.md "Single ownership".