update

backend/models.py

@@ -32,6 +32,7 @@ class BlocksCreateRequest(BaseModel):
     source_location: str = Field(default="", max_length=2000)
     ab_phase: int | None = Field(default=None, ge=1, le=9)  # re-run from a coarse phase (position in _phasen(topic), 1-based; up to 9: …outline/questions/artifacts); None = resume/continue without deleting
     ab_step: int | None = Field(default=None, ge=0)  # re-run from a fine sub-step (0-based index into _blocks_steps); takes precedence over ab_phase
+    to_step: int | None = Field(default=None, ge=0)  # stop AFTER this fine sub-step (0-based index into _blocks_steps); None = run to the end
 
 
 class BlocksResetStepRequest(BaseModel):