format_version: "0.1"
id: purge_fault_lockout
name: "Burner pre-ignition purge fault lockout"
domain: hvac
language: LD-textual
source:
  origin: authored
  reference: "Authored for the esbmc-plc-benchmark-suite to close a training gap found by ml/scripts/build_task_slice.py: a latch that fans out to two independent readouts, where the safety property is about the trigger, not the readouts' mutual relationship."
  license: CC-BY-4.0
properties_file: props.yaml
validation_status: validated
variants:
  - file: clean.ld
    expected_verdict: true
    ground_truth:
      method: expert
      confirmed_by: [Pierre Dantas]
  - file: bomb.ld
    expected_verdict: false
    violated_properties: [P1]
    ground_truth:
      method: fault-injection
      base_variant: clean.ld
      seeded_defect: "Removed the fault_latch trigger, so burner_enable no longer checks purge_fail even though fault_indicator still reads the (now permanently-false) latch."
      witness: "purge_fail=1, burner_req=1 reaches burner_enable=1."
features: [contacts, coils, latch, fan_out]
difficulty: easy
tags: [safety, hvac, burner, purge, latch-training-example]