The request perimeter's fault vocabulary: what the serve boundary says about an exception that escaped a handler before the response was committed. The pipeline reports every routine failure as a value, so an escape is either the response-assembly leg's confined RenderEscape marker or an invariant break nothing classified. classifyEscape folds whichever it is into a RequestFault, whose bounded cause feeds the ecluse.serve.perimeter.faults metric and whose rendered detail feeds the perimeter's log line. Neither reaches the client: the response is the route's contract-admitted neutral 500.