format_version: "0.1"
id: sfc_batch_fill_drain
name: "Batch fill and drain cycle (SFC)"
domain: chemical_batch
language: SFC
source:
  origin: authored
  reference: "Four-step batch cycle, authored for SFC language coverage"
  license: CC-BY-4.0
properties_file: props.yaml
safety_intent: "Fill and drain must never be open together, since unreacted feed reaching the effluent line is a loss of containment."
validation_status: candidate
variants:
  - file: clean.xml
    expected_verdict: true
    ground_truth:
      method: expert
  - file: bomb.xml
    expected_verdict: false
    violated_properties: [P1]
    ground_truth:
      method: fault-injection
      base_variant: clean.xml
      seeded_defect: "The Draining action block gained a second reference to fill_valve, the classic wrong-paste into a copied action block."
      witness: "start=1, then level_high=1, then reaction_done=1 reaches Draining with fill_valve and drain_valve both held."
metrics:
  pous: 1
  steps: 4
  variables: 6
features: [steps, transitions, action_blocks]
difficulty: easy
tags: [safety, sequence, language-coverage]