fix: 拼音 fallback 逐字 SinglePinyin，解决词典缺失字对齐失步

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

biz/consts/pinyin.go

@@ -33,16 +33,16 @@ var PinyinOverrides = map[string]string{
 	"上屋抽梯": "shàng wū chōu tī",
 	"树上开花": "shù shàng kāi huā",
 	"反客为主": "fǎn kè wéi zhǔ",
-	"美人计":   "měi rén jì",
-	"空城计":   "kōng chéng jì",
-	"反间计":   "fǎn jiàn jì",
-	"苦肉计":   "kǔ ròu jì",
-	"连环计":   "lián huán jì",
+	"美人计":  "měi rén jì",
+	"空城计":  "kōng chéng jì",
+	"反间计":  "fǎn jiàn jì",
+	"苦肉计":  "kǔ ròu jì",
+	"连环计":  "lián huán jì",
 	"走为上计": "zǒu wéi shàng jì",
 	// 种子内容常用专名（扫描 seed_36_ji/*.json 的人物/场景名补充，发现多音误标就加）
-	"小明": "xiǎo míng",
-	"小虎": "xiǎo hǔ",
-	"朵朵": "duǒ duǒ",
+	"小明":  "xiǎo míng",
+	"小虎":  "xiǎo hǔ",
+	"朵朵":  "duǒ duǒ",
 	"幼儿园": "yòu ér yuán",
 	"足球场": "zú qiú chǎng",
 	"游乐场": "yóu lè chǎng",

common/pinyin.go

@@ -49,19 +49,17 @@ func AnnotatePinyin(text string) string {
 		}
 	}
 
-	// 未命中汉字逐字转拼音；pi 与 pinyin.Pinyin 的汉字输出顺序同步推进
-	args := pinyin.NewArgs()
-	args.Style = pinyin.Tone
-	all := pinyin.Pinyin(string(runes), args)
-	pi := 0
-	for idx, r := range runes {
-		if !unicode.Is(unicode.Han, r) {
-			continue
+	// 未命中汉字逐字转拼音：词典缺失字（生僻字等）SinglePinyin 返回空串，
+	// 该字自然保持 ""，后续字不错位
+	args := pinyin.Args{Style: pinyin.Tone}
+	i := 0
+	for _, r := range text {
+		if out[i] == "" && unicode.Is(unicode.Han, r) {
+			if pys := pinyin.SinglePinyin(r, args); len(pys) > 0 {
+				out[i] = pys[0]
+			}
 		}
-		if out[idx] == "" && pi < len(all) && len(all[pi]) > 0 {
-			out[idx] = all[pi][0]
-		}
-		pi++
+		i++
 	}
 
 	b, _ := json.Marshal(out)

common/pinyin_test.go

@@ -59,3 +59,17 @@ func TestAnnotatePinyin_Empty(t *testing.T) {
 		t.Fatal("空文本应返回 []")
 	}
 }
+
+func TestAnnotatePinyin_MissingDictRune(t *testing.T) {
+	// 词典缺失字（兙 在 CJK 范围但 go-pinyin 词典未收录）保持空串，后续字不错位
+	pys := parse(t, AnnotatePinyin("兙好"))
+	want := []string{"", "hǎo"}
+	if len(pys) != len(want) {
+		t.Fatalf("长度 %d != %d: %v", len(pys), len(want), pys)
+	}
+	for i := range want {
+		if pys[i] != want[i] {
+			t.Fatalf("第 %d 字 %q != %q", i, pys[i], want[i])
+		}
+	}
+}