Option C is the only approach that guarantees the required terminal condition independently of the model’s behavior. When the agent loop stops, the orchestration layer evaluates the recorded outcome. If neither a successful resolution nor a confirmed human escalation occurred, deterministic application code invokes escalate_to_human using the information accumulated before termination.

The max_turns limit is a host-controlled safety boundary. Once that boundary is reached, the model may no longer have an opportunity to follow a prompt instruction or make another tool call. Therefore, the required fallback cannot depend entirely on Claude deciding to escalate before its remaining turns are exhausted.

Option A escalates based on an arbitrary 80% threshold and may prematurely terminate cases that could have been resolved successfully within the remaining budget. Option B provides additional turn capacity but does not guarantee that the second agent will complete its work or escalate before its own limit is reached. Option D remains probabilistic and cannot operate after an unexpected termination has already occurred.

The orchestration fallback should be idempotent, ensuring that repeated completion checks cannot create duplicate escalation records. It should also include verified customer information, relevant order data, completed actions, failure reasons, and the unresolved request in the handoff payload.

Official references/topics: Agent-loop termination, deterministic fallback orchestration, terminal-state validation, human handoff guarantees.