fix: preserve keyboard subtitle navigation state

src/core/services/tokenizer/parser-selection-stage.test.ts

@@ -51,7 +51,7 @@ test('prefers scanning parser when scanning candidate has more than one token',
 test('keeps scanning parser candidate when scanning candidate is single token', () => {
   const parseResults = [
     makeParseItem('scanning-parser', [
-      [{ text: '俺は公園にいきたい', reading: 'おれはこうえんにいきたい' }],
+      [{ text: '俺は公園にいきたい', reading: 'おれはこうえんにいきたい', headword: '行きたい' }],
     ]),
     makeParseItem('mecab', [
       [{ text: '俺', reading: 'おれ', headword: '俺' }],
@@ -96,3 +96,34 @@ test('returns null when only mecab-source candidates are present', () => {
   const tokens = selectYomitanParseTokens(parseResults, () => false, 'headword');
   assert.equal(tokens, null);
 });
+
+test('returns null when scanning parser candidates have no dictionary headwords', () => {
+  const parseResults = [
+    makeParseItem('scanning-parser', [
+      [{ text: 'これは', reading: 'これは' }],
+      [{ text: 'テスト', reading: 'てすと' }],
+    ]),
+  ];
+
+  const tokens = selectYomitanParseTokens(parseResults, () => false, 'headword');
+  assert.equal(tokens, null);
+});
+
+test('drops scanning parser tokens which have no dictionary headword', () => {
+  const parseResults = [
+    makeParseItem('scanning-parser', [
+      [{ text: '(ダクネスの荒い息)', reading: 'だくねすのあらいいき' }],
+      [{ text: 'アクア', reading: 'あくあ', headword: 'アクア' }],
+      [{ text: 'トラウマ', reading: 'とらうま', headword: 'トラウマ' }],
+    ]),
+  ];
+
+  const tokens = selectYomitanParseTokens(parseResults, () => false, 'headword');
+  assert.deepEqual(
+    tokens?.map((token) => ({ surface: token.surface, headword: token.headword })),
+    [
+      { surface: 'アクア', headword: 'アクア' },
+      { surface: 'トラウマ', headword: 'トラウマ' },
+    ],
+  );
+});

src/core/services/tokenizer/parser-selection-stage.ts

@@ -130,6 +130,7 @@ export function mapYomitanParseResultItemToMergedTokens(
   const tokens: MergedToken[] = [];
   let charOffset = 0;
   let validLineCount = 0;
+  let hasDictionaryMatch = false;
 
   for (const line of content) {
     if (!isYomitanParseLine(line)) {
@@ -163,7 +164,13 @@ export function mapYomitanParseResultItemToMergedTokens(
     const start = charOffset;
     const end = start + combinedSurface.length;
     charOffset = end;
-    const headword = combinedHeadword || combinedSurface;
+    if (!combinedHeadword) {
+      // No dictionary-backed headword for this merged unit; skip it entirely so
+      // downstream keyboard/frequency/JLPT flows only operate on lookup-backed tokens.
+      continue;
+    }
+    hasDictionaryMatch = true;
+    const headword = combinedHeadword;
 
     tokens.push({
       surface: combinedSurface,
@@ -182,7 +189,7 @@ export function mapYomitanParseResultItemToMergedTokens(
     });
   }
 
-  if (validLineCount === 0 || tokens.length === 0) {
+  if (validLineCount === 0 || tokens.length === 0 || !hasDictionaryMatch) {
     return null;
   }