UUID of an approved governance Decision whose planned_operations list this endpoint together with the exact request payload. The matching planned step must not yet have been executed. Planned operations may contain {{step.<n>.json.<path>}} references to earlier steps' responses: the gate resolves them against the recorded outputs before matching, so send the RESOLVED body and fire steps in order — a step whose references are not yet resolvable cannot match. Required for MCP callers; HumanReviewer callers bypass the gate by default.