fix: prevent memory leaks on consecutive fight replays

- FightViewer: store canvas event handlers and remove them before
  replacing canvas elements, preventing detached DOM/closure leaks
- FightViewer: clean up canvas listeners on unmount
- tts.ts: clear _staticLoading dedup map after precache completes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/FightViewer.vue

@@ -30,6 +30,8 @@ let cleanupTimerHandle: ReturnType<typeof setTimeout> | null = null
 let destroyed = false
 let initializingScene = false
 const contextLost = ref(false)
+let canvasContextLostHandler: ((e: Event) => void) | null = null
+let canvasContextRestoredHandler: (() => void) | null = null
 
 const isReplaying = ref(false)
 const ttsProgress = ref(-1)
@@ -171,6 +173,14 @@ onUnmounted(() => {
   stopAllAudio()
   sceneReady.value = false
   if (scene) { scene.destroy(); scene = null }
+  // Remove canvas event listeners to prevent detached DOM leaks
+  const canvas = canvasRef.value
+  if (canvas && canvasContextLostHandler) {
+    canvas.removeEventListener('webglcontextlost', canvasContextLostHandler)
+    canvas.removeEventListener('webglcontextrestored', canvasContextRestoredHandler!)
+  }
+  canvasContextLostHandler = null
+  canvasContextRestoredHandler = null
   if (cleanupTimerHandle) { clearTimeout(cleanupTimerHandle); cleanupTimerHandle = null }
   if (ttsProgressTimer) { clearInterval(ttsProgressTimer); ttsProgressTimer = null }
   if (typeof speechSynthesis !== 'undefined') speechSynthesis.cancel()
@@ -194,6 +204,11 @@ async function initScene() {
 
   // Replace canvas element so Kaplay gets a fresh context
   const oldCanvas = canvasRef.value
+  // Remove old canvas event listeners to prevent memory leaks
+  if (oldCanvas && canvasContextLostHandler) {
+    oldCanvas.removeEventListener('webglcontextlost', canvasContextLostHandler)
+    oldCanvas.removeEventListener('webglcontextrestored', canvasContextRestoredHandler!)
+  }
   const newCanvas = document.createElement('canvas')
   newCanvas.className = 'w-full h-full block'
   newCanvas.width = container.clientWidth || 800
@@ -207,17 +222,19 @@ async function initScene() {
   contextLost.value = false
 
   // Handle WebGL/Canvas context loss (GPU pressure, tab backgrounding, etc.)
-  newCanvas.addEventListener('webglcontextlost', (e) => {
+  canvasContextLostHandler = (e: Event) => {
     e.preventDefault() // Allow context restoration
     contextLost.value = true
     sceneReady.value = false
-  })
-  newCanvas.addEventListener('webglcontextrestored', () => {
+  }
+  canvasContextRestoredHandler = () => {
     // Don't auto-reinit during replay — just mark context as restored
     // The contextLost overlay will let users tap to reload if needed
     contextLost.value = false
     if (!isReplaying.value) initScene()
-  })
+  }
+  newCanvas.addEventListener('webglcontextlost', canvasContextLostHandler)
+  newCanvas.addEventListener('webglcontextrestored', canvasContextRestoredHandler)
 
   // Wrap scene creation in try/catch + timeout so a mobile sprite loading failure
   // or hang never blocks the overlay/voice/round flow

frontend/src/game/tts.ts

@@ -358,6 +358,8 @@ async function _precacheCommon() {
   }
   _precacheDone = true
   _precacheRunning = false
+  // Release dedup promises — they hold closures referencing fetch/decode state
+  _staticLoading.clear()
 }
 
 function _cacheKey(text: string, profile: string): string {