From 35946624c29f4c96daaf6e316834bc93f03052c9 Mon Sep 17 00:00:00 2001
From: sudacode <suda@sudacode.com>
Date: Sun, 15 Mar 2026 12:46:43 -0700
Subject: [PATCH] feat: add preCacheTokenization and isCacheFull to
 SubtitleProcessingController

---
 .../subtitle-processing-controller.test.ts    | 42 +++++++++++++++++++
 .../subtitle-processing-controller.ts         |  8 ++++
 2 files changed, 50 insertions(+)

diff --git a/src/core/services/subtitle-processing-controller.test.ts b/src/core/services/subtitle-processing-controller.test.ts
index 860eb5e..cc6095b 100644
--- a/src/core/services/subtitle-processing-controller.test.ts
+++ b/src/core/services/subtitle-processing-controller.test.ts
@@ -170,3 +170,45 @@ test('subtitle processing cache invalidation only affects future subtitle events
 
   assert.equal(callsByText.get('same'), 2);
 });
+
+test('preCacheTokenization stores entry that is returned on next subtitle change', async () => {
+  const emitted: SubtitleData[] = [];
+  let tokenizeCalls = 0;
+  const controller = createSubtitleProcessingController({
+    tokenizeSubtitle: async (text) => {
+      tokenizeCalls += 1;
+      return { text, tokens: [] };
+    },
+    emitSubtitle: (payload) => emitted.push(payload),
+  });
+
+  controller.preCacheTokenization('予め', { text: '予め', tokens: [] });
+  controller.onSubtitleChange('予め');
+  await flushMicrotasks();
+
+  assert.equal(tokenizeCalls, 0, 'should not call tokenize when pre-cached');
+  assert.deepEqual(emitted, [{ text: '予め', tokens: [] }]);
+});
+
+test('isCacheFull returns false when cache is below limit', () => {
+  const controller = createSubtitleProcessingController({
+    tokenizeSubtitle: async (text) => ({ text, tokens: null }),
+    emitSubtitle: () => {},
+  });
+
+  assert.equal(controller.isCacheFull(), false);
+});
+
+test('isCacheFull returns true when cache reaches limit', async () => {
+  const controller = createSubtitleProcessingController({
+    tokenizeSubtitle: async (text) => ({ text, tokens: [] }),
+    emitSubtitle: () => {},
+  });
+
+  // Fill cache to the 256 limit
+  for (let i = 0; i < 256; i += 1) {
+    controller.preCacheTokenization(`line-${i}`, { text: `line-${i}`, tokens: [] });
+  }
+
+  assert.equal(controller.isCacheFull(), true);
+});
diff --git a/src/core/services/subtitle-processing-controller.ts b/src/core/services/subtitle-processing-controller.ts
index 20ea805..aebe820 100644
--- a/src/core/services/subtitle-processing-controller.ts
+++ b/src/core/services/subtitle-processing-controller.ts
@@ -11,6 +11,8 @@ export interface SubtitleProcessingController {
   onSubtitleChange: (text: string) => void;
   refreshCurrentSubtitle: (textOverride?: string) => void;
   invalidateTokenizationCache: () => void;
+  preCacheTokenization: (text: string, data: SubtitleData) => void;
+  isCacheFull: () => boolean;
 }
 
 export function createSubtitleProcessingController(
@@ -130,5 +132,11 @@ export function createSubtitleProcessingController(
     invalidateTokenizationCache: () => {
       tokenizationCache.clear();
     },
+    preCacheTokenization: (text: string, data: SubtitleData) => {
+      setCachedTokenization(text, data);
+    },
+    isCacheFull: () => {
+      return tokenizationCache.size >= SUBTITLE_TOKENIZATION_CACHE_LIMIT;
+    },
   };
 }