feat(music-lab): pipeline 메타데이터 LLM 생성 + 폴백

music-lab/app/pipeline/metadata.py

@@ -0,0 +1,95 @@
+"""메타데이터 생성 — Claude Haiku + 템플릿 폴백."""
+import os
+import json
+import logging
+
+import httpx
+
+logger = logging.getLogger("music-lab.metadata")
+
+CLAUDE_HAIKU_MODEL_DEFAULT = "claude-haiku-4-5-20251001"
+TIMEOUT_S = 30
+
+
+def _get_api_key() -> str:
+    return os.getenv("ANTHROPIC_API_KEY", "")
+
+
+def _get_model() -> str:
+    return os.getenv("CLAUDE_HAIKU_MODEL", CLAUDE_HAIKU_MODEL_DEFAULT)
+
+
+async def generate(*, track: dict, template: dict, trend_keywords: list[str],
+                   feedback: str = "") -> 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"}
+
+    try:
+        result = await _call_claude(track, template, trend_keywords, feedback,
+                                    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)}
+
+
+def _fallback_template(track: dict, template: dict) -> dict:
+    fmt_vars = {
+        "title": track.get("title", ""),
+        "genre": track.get("genre", ""),
+        "bpm": track.get("bpm", ""),
+        "key": track.get("key", ""),
+        "scale": track.get("scale", ""),
+    }
+    title = template.get("title", "{title}").format(**fmt_vars)
+    description = template.get("description", "{title}").format(**fmt_vars)
+    return {
+        "title": title[:100],
+        "description": description[:5000],
+        "tags": (template.get("tags") or [])[:15],
+        "category_id": template.get("category_id", 10),
+    }
+
+
+async def _call_claude(track: dict, template: dict, trend_keywords: list[str],
+                        feedback: str, *, 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 feedback:
+        user_prompt += f"\n사용자 피드백: {feedback}\n"
+    user_prompt += (
+        '\n출력 JSON: {"title": "60자 이내", "description": "1000자 이내, 3-5문단",'
+        ' "tags": ["15개 이내"], "category_id": 10}'
+    )
+
+    async with httpx.AsyncClient(timeout=TIMEOUT_S) as client:
+        resp = await client.post(
+            "https://api.anthropic.com/v1/messages",
+            headers={
+                "x-api-key": api_key,
+                "anthropic-version": "2023-06-01",
+                "content-type": "application/json",
+            },
+            json={
+                "model": model,
+                "max_tokens": 1024,
+                "messages": [{"role": "user", "content": user_prompt}],
+            },
+        )
+        resp.raise_for_status()
+        text = resp.json()["content"][0]["text"]
+        # 가장 첫 JSON 블록 추출
+        start = text.find("{")
+        end = text.rfind("}") + 1
+        if start < 0 or end <= start:
+            raise ValueError("Claude 응답에 JSON 블록 없음")
+        return json.loads(text[start:end])