diff --git a/music-lab/app/pipeline/metadata.py b/music-lab/app/pipeline/metadata.py
index c5b12ba..f84fe27 100644
--- a/music-lab/app/pipeline/metadata.py
+++ b/music-lab/app/pipeline/metadata.py
@@ -19,26 +19,46 @@ def _get_model() -> str:
     return os.getenv("CLAUDE_HAIKU_MODEL", CLAUDE_HAIKU_MODEL_DEFAULT)
 
 
+def _format_chapters(tracks: list[dict]) -> str:
+    """YouTube 챕터 자동 인식 형식: '[mm:ss] 제목' 한 줄씩.
+
+    1시간 이상이면 hh:mm:ss 형식.
+    """
+    if not tracks:
+        return ""
+    lines = []
+    for t in tracks:
+        offset = int(t.get("start_offset_sec", 0))
+        m, s = divmod(offset, 60)
+        h, m = divmod(m, 60)
+        if h > 0:
+            ts = f"{h:02d}:{m:02d}:{s:02d}"
+        else:
+            ts = f"{m:02d}:{s:02d}"
+        lines.append(f"{ts} {t.get('title', '')}")
+    return "\n".join(lines)
+
+
 async def generate(*, track: dict, template: dict, trend_keywords: list[str],
-                   feedback: str = "") -> dict:
+                   feedback: str = "", tracks: list[dict] | None = None) -> dict:
     """메타데이터 생성. 성공 시 LLM, 실패/미설정 시 템플릿 치환 폴백.
 
     반환: {"title", "description", "tags", "category_id", "used_fallback", "error"}
     """
     api_key = _get_api_key()
     if not api_key:
-        return {**_fallback_template(track, template), "used_fallback": True, "error": "no api key"}
+        return {**_fallback_template(track, template, tracks), "used_fallback": True, "error": "no api key"}
 
     try:
-        result = await _call_claude(track, template, trend_keywords, feedback,
+        result = await _call_claude(track, template, trend_keywords, feedback, tracks,
                                     api_key=api_key, model=_get_model())
         return {**result, "used_fallback": False, "error": None}
     except (httpx.HTTPError, httpx.TimeoutException, KeyError, ValueError, json.JSONDecodeError) as e:
         logger.warning("메타데이터 LLM 실패 — 폴백: %s", e)
-        return {**_fallback_template(track, template), "used_fallback": True, "error": str(e)}
+        return {**_fallback_template(track, template, tracks), "used_fallback": True, "error": str(e)}
 
 
-def _fallback_template(track: dict, template: dict) -> dict:
+def _fallback_template(track: dict, template: dict, tracks: list[dict] | None = None) -> dict:
     fmt_vars = {
         "title": track.get("title", ""),
         "genre": track.get("genre", ""),
@@ -48,6 +68,8 @@ def _fallback_template(track: dict, template: dict) -> dict:
     }
     title = template.get("title", "{title}").format(**fmt_vars)
     description = template.get("description", "{title}").format(**fmt_vars)
+    if tracks and len(tracks) > 1:
+        description = description + "\n\n" + _format_chapters(tracks)
     return {
         "title": title[:100],
         "description": description[:5000],
@@ -57,17 +79,24 @@ def _fallback_template(track: dict, template: dict) -> dict:
 
 
 async def _call_claude(track: dict, template: dict, trend_keywords: list[str],
-                        feedback: str, *, api_key: str, model: str) -> dict:
+                        feedback: str, tracks: list[dict] | None,
+                        *, api_key: str, model: str) -> dict:
     user_prompt = (
         "다음 트랙의 YouTube 메타데이터를 생성하세요. JSON으로만 응답.\n\n"
         f"트랙: {json.dumps(track, ensure_ascii=False)}\n"
         f"템플릿: {json.dumps(template, ensure_ascii=False)}\n"
         f"트렌드 키워드: {', '.join(trend_keywords)}\n"
     )
+    if tracks and len(tracks) > 1:
+        chapters = _format_chapters(tracks)
+        user_prompt += (
+            f"\n이 영상은 {len(tracks)}개 트랙의 mix입니다. "
+            f"description에 다음 챕터 리스트를 그대로 포함하세요 (YouTube 자동 챕터 인식용):\n{chapters}\n"
+        )
     if feedback:
         user_prompt += f"\n사용자 피드백: {feedback}\n"
     user_prompt += (
-        '\n출력 JSON: {"title": "60자 이내", "description": "1000자 이내, 3-5문단",'
+        '\n출력 JSON: {"title": "60자 이내", "description": "1000자 이내",'
         ' "tags": ["15개 이내"], "category_id": 10}'
     )
 
@@ -81,7 +110,7 @@ async def _call_claude(track: dict, template: dict, trend_keywords: list[str],
             },
             json={
                 "model": model,
-                "max_tokens": 1024,
+                "max_tokens": 2048,  # mix 더 길어서
                 "messages": [{"role": "user", "content": user_prompt}],
             },
         )
diff --git a/music-lab/tests/test_metadata_generation.py b/music-lab/tests/test_metadata_generation.py
index b890896..ee26cfc 100644
--- a/music-lab/tests/test_metadata_generation.py
+++ b/music-lab/tests/test_metadata_generation.py
@@ -80,3 +80,75 @@ async def test_metadata_falls_back_on_api_error(monkeypatch):
     )
     assert result["used_fallback"] is True
     assert "Drive" in result["title"]
+
+
+@pytest.mark.asyncio
+@respx.mock
+async def test_metadata_with_tracks_includes_chapter_format(monkeypatch):
+    monkeypatch.setenv("ANTHROPIC_API_KEY", "k")
+    captured = {}
+
+    def hook(req):
+        import json as _json
+        captured["body"] = _json.loads(req.content)
+        return Response(200, json={"content": [{"type": "text", "text":
+            '{"title":"Lo-Fi Mix 3 Tracks","description":"Track 1: [00:00] T1\\nTrack 2: [03:00] T2",'
+            '"tags":["lofi","mix"],"category_id":10}'}]})
+
+    respx.post("https://api.anthropic.com/v1/messages").mock(side_effect=hook)
+    result = await metadata.generate(
+        track={"title": "Mix", "genre": "mix", "duration_sec": 600,
+               "moods": []},
+        template={"title": "{title}", "description": "{title}",
+                  "tags": [], "category_id": 10},
+        trend_keywords=[],
+        tracks=[
+            {"id": 1, "title": "T1", "start_offset_sec": 0, "duration_sec": 180},
+            {"id": 2, "title": "T2", "start_offset_sec": 180, "duration_sec": 200},
+            {"id": 3, "title": "T3", "start_offset_sec": 380, "duration_sec": 220},
+        ],
+    )
+    body_str = str(captured["body"])
+    assert "T1" in body_str and "T2" in body_str and "T3" in body_str
+    assert "00:00" in body_str
+    assert result["used_fallback"] is False
+
+
+@pytest.mark.asyncio
+async def test_metadata_fallback_with_tracks(monkeypatch):
+    """API 키 없을 때 폴백에서도 트랙 챕터 포함."""
+    monkeypatch.delenv("ANTHROPIC_API_KEY", raising=False)
+    result = await metadata.generate(
+        track={"title": "Mix", "genre": "mix", "duration_sec": 600, "moods": []},
+        template={"title": "{title}", "description": "{title}",
+                  "tags": [], "category_id": 10},
+        trend_keywords=[],
+        tracks=[
+            {"id": 1, "title": "T1", "start_offset_sec": 0, "duration_sec": 180},
+            {"id": 2, "title": "T2", "start_offset_sec": 180, "duration_sec": 200},
+        ],
+    )
+    assert result["used_fallback"] is True
+    assert "00:00" in result["description"]
+    assert "T1" in result["description"]
+    assert "T2" in result["description"]
+
+
+def test_format_chapters_under_hour():
+    from app.pipeline.metadata import _format_chapters
+    out = _format_chapters([
+        {"start_offset_sec": 0, "title": "T1"},
+        {"start_offset_sec": 180, "title": "T2"},
+    ])
+    assert "00:00 T1" in out
+    assert "03:00 T2" in out
+
+
+def test_format_chapters_over_hour():
+    from app.pipeline.metadata import _format_chapters
+    out = _format_chapters([
+        {"start_offset_sec": 0, "title": "T1"},
+        {"start_offset_sec": 3700, "title": "T2"},
+    ])
+    assert "00:00 T1" in out
+    assert "01:01:40 T2" in out