clearFixInFlight function
Deletes the carry at workspaceDir — every exit that does NOT advance with
a finding, plus IntakeCapability's session-head hygiene. Best-effort: a
delete that fails never gates an otherwise-passing spec.
Implementation
void clearFixInFlight(String workspaceDir) {
try {
final file = File(fixInFlightPath(workspaceDir));
if (file.existsSync()) file.deleteSync();
} catch (_) {
// Hygiene only — the next advance overwrites it anyway.
}
}