feat: add workflow output comparison tooling

backend/app/domains/rendering/workflow_router.py

@@ -15,8 +15,10 @@ from app.domains.rendering.schemas import (
     WorkflowDefinitionCreate,
     WorkflowDefinitionUpdate,
     WorkflowDefinitionOut,
+    WorkflowRunComparisonOut,
     WorkflowRunOut,
 )
+from app.domains.rendering.workflow_comparison_service import build_workflow_run_comparison
 from app.domains.rendering.workflow_config_utils import canonicalize_workflow_config
 from app.domains.rendering.workflow_node_registry import (
     StepCategory,
@@ -199,6 +201,18 @@ async def list_workflow_runs(
     return result.scalars().all()
 
 
+@router.get("/runs/{run_id}/comparison", response_model=WorkflowRunComparisonOut)
+async def get_workflow_run_comparison(
+    run_id: uuid.UUID,
+    _user: User = Depends(require_admin_or_pm),
+    db: AsyncSession = Depends(get_db),
+):
+    comparison = await build_workflow_run_comparison(db, run_id)
+    if comparison is None:
+        raise HTTPException(status_code=404, detail="Workflow run not found")
+    return comparison
+
+
 class WorkflowDispatchResponse(BaseModel):
     workflow_run: WorkflowRunOut
     context_id: str