feat: 转场特效引擎 — TransitionEngine + 14种转场预设 + 时长边界校验 + 降级策略

apps/api/app/api/routes/edit_plans.py

@@ -146,6 +146,7 @@ class AIRecommendClipItem(BaseModel):
     text_content: str = Field(default="", description="文字内容")
     duration: float = Field(..., ge=0.0, description="片段时长（秒）")
     transition_effect: str = Field(default="cut", description="转场效果")
+    transition_duration: float = Field(default=0.0, ge=0.0, description="转场时长（秒），0 表示使用默认值")
     asset_id: str = Field(default="", description="关联素材 ID")
     start_time: float = Field(default=0.0, ge=0.0, description="素材截取起始时间（秒）")
     config: dict[str, Any] = Field(default_factory=dict, description="片段额外配置")
@@ -209,6 +210,7 @@ class _PlanClipItem(BaseModel):
     start_time: float
     duration: float
     transition_effect: str
+    transition_duration: float
     status: str
     config: Optional[dict[str, Any]] = None
     created_at: datetime

apps/api/app/api/routes/edit_plans_timeline.py

@@ -210,6 +210,7 @@ def generate_from_template(
                 start_time=c.start_time,
                 duration=c.duration,
                 transition_effect=c.transition_effect,
+                transition_duration=c.transition_duration,
                 status=c.status.value if hasattr(c.status, "value") else c.status,
                 config=c.config,
                 created_at=c.created_at,

apps/api/app/services/edit_plan_service.py

@@ -281,6 +281,7 @@ class EditPlanService:
         start_time: float = 0.0,
         duration: float = 0.0,
         transition_effect: str = "cut",
+        transition_duration: float = 0.0,
         config: Optional[dict[str, Any]] = None,
     ) -> EditPlanClip:
         """创建片段
@@ -301,6 +302,7 @@ class EditPlanService:
             start_time=start_time,
             duration=duration,
             transition_effect=transition_effect,
+            transition_duration=transition_duration,
             config=config,
         )
         created = self._clip_repo.create(clip)
@@ -324,6 +326,7 @@ class EditPlanService:
         start_time: Optional[float] = None,
         duration: Optional[float] = None,
         transition_effect: Optional[str] = None,
+        transition_duration: Optional[float] = None,
         config: Optional[dict[str, Any]] = None,
     ) -> EditPlanClip:
         """更新片段
@@ -346,6 +349,9 @@ class EditPlanService:
             transition_effect=(
                 transition_effect.strip() if transition_effect is not None else existing.transition_effect
             ),
+            transition_duration=(
+                transition_duration if transition_duration is not None else existing.transition_duration
+            ),
             status=existing.status,
             config=config if config is not None else existing.config,
             created_at=existing.created_at,