{
  "uid": "cogitave.learn.diyar-safety-and-evidence.summary",
  "kind": "moduleUnit",
  "href": "/modules/diyar-safety-and-evidence/summary/",
  "title": "Summary",
  "summary": "",
  "type": null,
  "products": [],
  "roles": [],
  "levels": [],
  "subjects": [],
  "headings": [
    "Next steps"
  ],
  "source": "You can now explain how Diyar keeps a kilowatt-class heater safe with no\nnetwork connection, and how a single sensor reading becomes evidence an\ninspector can trust.\n\nIn this module, you:\n\n- Learned the core rule, de-energize-to-trip, and the four layers that back\n  it: an independent hardware thermal cutoff (mandatory, survives a wedged\n  CPU), a hardware watchdog with fail-safe wiring, the software typestate\n  interlock (`Idle -> Armed -> Heating`), and worker enforcement that cuts the\n  heater on every exit path - plus the comms-loss watchdog a Modbus-driven\n  heat output must declare before profile validation will accept it.\n- Explained why a remote start from the cloud or a mobile client is a signed,\n  vetoable request the edge alone validates - never a command - and why the\n  device shadow's desired state is deliberately config-class only, never\n  actuation.\n- Traced a reading from the local journal (written before anything is\n  published) through the SHA-256 hash chain, the Merkle history tree that\n  proves completeness without shipping a whole session's history, and the\n  cloud's independent reconciliation and quarantine of anything that does not\n  match.\n- Learned, honestly, what is defense-in-depth versus a hardware guarantee: the\n  layer-3/4 heartbeat is cooperative and does not catch a thread parked in a\n  blocking call, the hash chain is tamper-evident rather than tamper-proof\n  against root access, and the Merkle root is not signed yet.\n\n## Next steps\n\n- @cogitave.learn.build-a-diyar-solution - the next module in **Introduction\n  to Cogitave Diyar**, on the signed device profile, the certified\n  verdict-engine registry, and how ISPM-15 became Diyar's first certified\n  solution.\n- Keep \"the edge is the only thing that can ever actuate\" in mind - the next\n  module builds a device's whole authority model on top of exactly that\n  boundary.\n",
  "partOf": "cogitave.learn.diyar-safety-and-evidence",
  "durationInMinutes": 3,
  "quiz": null
}