User{{seq-party-1}}

API{{seq-party-2}}

Legacy service{{seq-party-3}}

Target-only participant: {{seq-party-4}}

Current path

User → APIsync {{current-call}}

API → Legacy servicesync Forward through the existing coupling.

Legacy service → Usererror Expose the current failure path.

UserStarts the same request.

OrchestratorCoordinates the target request path.

Focused serviceOwns one clear responsibility.

Target path

User → Orchestratorsync {{target-call}}

Orchestrator → Focused serviceasync Dispatch through the target contract.

Focused service → Userreturn Return an explicit target result.

{{title}}