feat(studio): 回退/重roll 与 R5 用户确认下一步

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/models/studio_models.py

@@ -183,6 +183,14 @@ class PromptBlock(BaseModel):
     source: str = "auto"  # auto | manual | workflow
 
 
+class TurnSnapshot(BaseModel):
+    """State captured before each LLM turn (for undo)."""
+    lastDraft: Optional[Dict[str, Any]] = None
+    lastToolResponse: Optional[LastToolResponse] = None
+    stepMessages: List[StepMessage] = Field(default_factory=list)
+    timestamp: Optional[str] = None
+
+
 class StudioNodeRunState(BaseModel):
     nodeId: str
     displayName: str
@@ -192,6 +200,7 @@ class StudioNodeRunState(BaseModel):
     lastDraft: Optional[Dict[str, Any]] = None
     lastToolResponse: Optional[LastToolResponse] = None
     stepMessages: List[StepMessage] = Field(default_factory=list)
+    turnHistory: List[TurnSnapshot] = Field(default_factory=list)
 
 
 class StudioRun(BaseModel):
@@ -220,6 +229,12 @@ class RunMessageRequest(BaseModel):
     apiConfig: Optional[Dict[str, str]] = None
 
 
+class RunRerollRequest(BaseModel):
+    stream: bool = False
+    profileId: Optional[str] = None
+    apiConfig: Optional[Dict[str, str]] = None
+
+
 class RenameRunRequest(BaseModel):
     title: str = Field(..., min_length=1, max_length=120)