Single conflict on studio/backend/core/inference/external_provider.py:
main added `previous_response_id` plumbing for OpenAI Responses chaining
in the same body-builder block PR 5711 uses for service_tier /
parallel_tool_calls. Kept both sets — service_tier+parallel_tool_calls
write first, then previous_response_id appends. No behavioural change
to either feature.
163 backend routing tests still pass; frontend tsc clean.
60085606a7