fix(tokenizer): avoid repeated yomitan anki sync checks on no-change

backlog/tasks/task-81 - Tokenization-performance-disable-yomitan-mecab-and-persistent-local-mecab.md

@@ -4,7 +4,7 @@ title: 'Tokenization performance: disable Yomitan MeCab parser, gate local MeCab
 status: Done
 assignee: []
 created_date: '2026-03-02 07:44'
-updated_date: '2026-03-02 09:20'
+updated_date: '2026-03-02 20:34'
 labels: []
 dependencies: []
 priority: high
@@ -45,6 +45,8 @@ Implemented tokenizer latency optimizations:
 - added regression tests for Yomitan parse flag, MeCab warmup gating, and persistent/idle lifecycle behavior;
 - fixed tokenization warmup gate so first-use warmup completion is sticky (`tokenizationWarmupCompleted`) and sequential `tokenizeSubtitle` calls no longer re-run Yomitan/dictionary warmup path;
 - added regression coverage in `src/main/runtime/composers/mpv-runtime-composer.test.ts` for sequential tokenize calls (`warmup` side effects run once);
+- post-review critical fix: treat Yomitan default-profile Anki server sync `no-change` as successful check, so `lastSyncedYomitanAnkiServer` is cached and expensive sync checks do not repeat on every subtitle line;
+- added regression assertion in `src/core/services/tokenizer/yomitan-parser-runtime.test.ts` for `updated: false` path returning sync success;
 - validated with targeted tests and `tsc --noEmit`.
 
 <!-- SECTION:FINAL_SUMMARY:END -->

src/core/services/tokenizer/yomitan-parser-runtime.test.ts

@@ -44,15 +44,19 @@ test('syncYomitanDefaultAnkiServer updates default profile server when script re
   assert.equal(infoLogs.length, 1);
 });
 
-test('syncYomitanDefaultAnkiServer returns false when script reports no change', async () => {
+test('syncYomitanDefaultAnkiServer returns true when script reports no change', async () => {
   const deps = createDeps(async () => ({ updated: false }));
+  let infoLogCount = 0;
 
-  const updated = await syncYomitanDefaultAnkiServer('http://127.0.0.1:8766', deps, {
+  const synced = await syncYomitanDefaultAnkiServer('http://127.0.0.1:8766', deps, {
     error: () => undefined,
-    info: () => undefined,
+    info: () => {
+      infoLogCount += 1;
+    },
   });
 
-  assert.equal(updated, false);
+  assert.equal(synced, true);
+  assert.equal(infoLogCount, 0);
 });
 
 test('syncYomitanDefaultAnkiServer logs and returns false on script failure', async () => {

src/core/services/tokenizer/yomitan-parser-runtime.ts

@@ -846,7 +846,11 @@ export async function syncYomitanDefaultAnkiServer(
       logger.info?.(`Updated Yomitan default profile Anki server to ${normalizedTargetServer}`);
       return true;
     }
-    return false;
+    const checkedWithoutUpdate =
+      typeof result === 'object' &&
+      result !== null &&
+      (result as { updated?: unknown }).updated === false;
+    return checkedWithoutUpdate;
   } catch (err) {
     logger.error('Failed to sync Yomitan default profile Anki server:', (err as Error).message);
     return false;

src/main.ts

@@ -2627,7 +2627,7 @@ async function syncYomitanDefaultProfileAnkiServer(): Promise<void> {
     return;
   }
 
-  const updated = await syncYomitanDefaultAnkiServerCore(
+  const synced = await syncYomitanDefaultAnkiServerCore(
     targetUrl,
     {
       getYomitanExt: () => appState.yomitanExt,
@@ -2654,8 +2654,7 @@ async function syncYomitanDefaultProfileAnkiServer(): Promise<void> {
     },
   );
 
-  if (updated) {
-    logger.info(`Yomitan default profile Anki server set to ${targetUrl}`);
+  if (synced) {
     lastSyncedYomitanAnkiServer = targetUrl;
   }
 }