fix: 优化内容

engine/script_gen.py

@@ -33,6 +33,24 @@ def _system_prompt(scene_count: int, min_chars: int, max_chars: int) -> str:
 """
 
 
+def _refine_system_prompt(min_chars: int, max_chars: int) -> str:
+    return f"""你是短视频分镜润色助手。
+你会收到用户的原始创意 prompt、以及一组三分镜（其中主角设定需一致）。
+你的任务：只润色指定的一个 Scene，使其更具体、更镜头化、更适合生成视频，同时保持主角描述与其它分镜一致。
+
+硬性约束：
+1) 只修改目标 Scene，不要改其它 Scene。
+2) 目标 Scene 必须包含：image_prompt, video_motion, narration。
+3) narration 为中文旁白，每段控制在约 {min_chars}-{max_chars} 字左右。
+4) 输出只允许 JSON，不要解释、不要 markdown。
+
+输出 JSON Schema：
+{{
+  "scene": {{"image_prompt":"...","video_motion":"...","narration":"..."}}
+}}
+"""
+
+
 def generate_scenes(user_prompt: str, cfg: AppConfig) -> list[Scene]:
     scene_count = int(cfg.get("script_gen.scene_count", 3))
     min_chars = int(cfg.get("script_gen.narration_min_chars", 15))
@@ -78,3 +96,56 @@ def generate_scenes(user_prompt: str, cfg: AppConfig) -> list[Scene]:
             raise ValueError(f"Scene[{i}] missing required fields")
         scenes.append(Scene(image_prompt=image_prompt, video_motion=video_motion, narration=narration))
     return scenes
+
+
+def refine_scene(*, prompt: str, scenes: list[Scene], target_index: int, cfg: AppConfig) -> Scene:
+    if not (1 <= target_index <= len(scenes)):
+        raise ValueError("target_index out of range")
+
+    min_chars = int(cfg.get("script_gen.narration_min_chars", 15))
+    max_chars = int(cfg.get("script_gen.narration_max_chars", 20))
+
+    api_key_env = str(cfg.get("openai.api_key_env", "OPENAI_API_KEY"))
+    base_url_env = str(cfg.get("openai.base_url_env", "OPENAI_BASE_URL"))
+    model = str(cfg.get("openai.model", "gpt-4o-mini"))
+
+    api_key = os.environ.get(api_key_env)
+    if not api_key:
+        raise RuntimeError(f"Missing env var {api_key_env} for OpenAI API key")
+
+    client = OpenAI(
+        api_key=api_key,
+        base_url=os.environ.get(base_url_env) or None,
+    )
+
+    scenes_payload = [
+        {"image_prompt": s.image_prompt, "video_motion": s.video_motion, "narration": s.narration}
+        for s in scenes
+    ]
+    user_payload = {
+        "prompt": prompt,
+        "target_index": target_index,
+        "scenes": scenes_payload,
+    }
+
+    resp = client.chat.completions.create(
+        model=model,
+        messages=[
+            {"role": "system", "content": _refine_system_prompt(min_chars, max_chars)},
+            {"role": "user", "content": json.dumps(user_payload, ensure_ascii=False)},
+        ],
+        response_format={"type": "json_object"},
+        temperature=0.6,
+    )
+
+    content = resp.choices[0].message.content or "{}"
+    data: Any = json.loads(content)
+    s = data.get("scene")
+    if not isinstance(s, dict):
+        raise ValueError("Model refine output missing scene")
+    image_prompt = str(s.get("image_prompt", "")).strip()
+    video_motion = str(s.get("video_motion", "")).strip()
+    narration = str(s.get("narration", "")).strip()
+    if not image_prompt or not narration:
+        raise ValueError("Refined scene missing required fields")
+    return Scene(image_prompt=image_prompt, video_motion=video_motion, narration=narration)