FLX-8001: the ship gate withheld the bundle
Family: evidence/pack (the 8000 band)
SEAM-FIDELITY-SPEC §7: on any failure the gate writes no bundle and emits com.agentics.flux.ship.withheld. The decision names every check that failed -- the recomputed H, the record's binding and signature, the recomputed output digest and statistics, the re-evaluated properties, the state's age -- so the reason is in the event, not in the exit code.
Look it up offline
$ fluxsim explain FLX-8001
Every code is listed in the error index.