fix(paste): skip trailing space after CJK text in append smart spacing

src/helpers/smartSpacing.js

@@ -21,8 +21,17 @@ function applyPrepend(text, precedingChar) {
   return " " + text;
 }
 
+// Unspaced scripts (Han, kana) and CJK punctuation (Symbols and Punctuation,
+// Fullwidth/Halfwidth Forms, Vertical Forms, Compatibility Forms): a trailing
+// ASCII space after "你好" or "です。" violates East Asian typography and
+// accumulates as "你好 世界" gaps across consecutive dictations. Hangul is
+// excluded on purpose — Korean separates words with spaces.
+const ENDS_WITH_CJK =
+  /[\p{Script=Han}\p{Script=Hiragana}\p{Script=Katakana}\u3000-\u303f\uff00-\uff65\ufe10-\ufe1f\ufe30-\ufe4f]$/u;
+
 function applyAppend(text) {
   if (/\s$/.test(text)) return text;
+  if (ENDS_WITH_CJK.test(text)) return text;
   return text + " ";
 }
 

test/helpers/smartSpacing.test.js

@@ -98,6 +98,39 @@ test("append: handles empty transcript", () => {
   assert.equal(append(""), "");
 });
 
+test("append: no trailing space after CJK ideographs", () => {
+  assert.equal(append("你好"), "你好");
+  assert.equal(append("日本語"), "日本語");
+});
+
+test("append: no trailing space after kana", () => {
+  assert.equal(append("こんにちは"), "こんにちは");
+  assert.equal(append("カタカナ"), "カタカナ");
+});
+
+test("append: no trailing space after full-width punctuation", () => {
+  assert.equal(append("你好。"), "你好。");
+  assert.equal(append("すごい！"), "すごい！");
+  assert.equal(append("何？"), "何？");
+  assert.equal(append("はい、"), "はい、");
+  assert.equal(append("「引用」"), "「引用」");
+  assert.equal(append("（括弧）"), "（括弧）");
+});
+
+test("append: no trailing space after halfwidth CJK punctuation and vertical forms", () => {
+  assert.equal(append("ﾃｽﾄ｡"), "ﾃｽﾄ｡");
+  assert.equal(append("你好︒"), "你好︒");
+});
+
+test("append: last character decides for mixed-script text", () => {
+  assert.equal(append("hello 你好"), "hello 你好");
+  assert.equal(append("你好 hello"), "你好 hello ");
+});
+
+test("append: keeps trailing space after Hangul (Korean uses word spacing)", () => {
+  assert.equal(append("안녕하세요"), "안녕하세요 ");
+});
+
 test("returns text unchanged for unknown mode", () => {
   assert.equal(applySmartSpacing({ text: "hello", mode: "noop" }), "hello");
 });