Price watch

nika: v1
workflow:
  id: price-watch
  description: "Watch a product price, ping me when it drops below my target"

const:
  product_api: "https://api.shop.example.com/v1/products/macbook-air"
  alert_below: 899

secrets:
  alerts_webhook:
    source: env
    key: ALERTS_WEBHOOK_URL
    egress:                       # sanction the one send · the secret IS the URL
      - to: "nika:notify"
        host_from_self: true
permits:
  tools: ["nika:fetch", "nika:notify"]
  net:
    # TWO hosts, for two different reasons.
    #
    # `api.shop.example.com` is what `const.product_api` names — a literal
    # `check` can read, so a mismatch here is caught before the run.
    #
    # `hooks.slack.com` is the ALERT host, and it is the entry people leave
    # out. `host_from_self:` above sanctions the FLOW (this secret may be the
    # URL) — it does not grant the capability. The host stays unknown at
    # check, so it is judged at RUN against this bound: name the escalation
    # host here or the send is refused mid-run, the first time the price
    # actually drops. Swap it for wherever YOUR webhook lives.
    http: ["api.shop.example.com", "hooks.slack.com"]

tasks:
  check:
    invoke:
      tool: "nika:fetch"
      args:
        url: "${{ const.product_api }}"
        mode: jq
        jq: "."
    output:                           # named jq bindings over the raw response
      price: ".price"
      name: ".name"
    on_error:
      # Offline rehearsal · a sample ABOVE the target, so the gate below stays
      # closed and the dry run ends green with the alert skipped. The alert
      # path is therefore NOT exercised offline — which is exactly why the
      # `net:` bound above has to be right by reading, not by running.
      recover: { price: 949, name: "MacBook Air (offline sample)" }

  alert:
    with:
      price: ${{ tasks.check.price }}     # value edges · the named bindings cross the boundary here
      name: ${{ tasks.check.name }}
    when: ${{ with.price < const.alert_below }}
    invoke:
      tool: "nika:notify"
      args:
        channel: webhook
        target: "${{ secrets.alerts_webhook }}"
        message: "Price drop · ${{ with.name }} is now ${{ with.price }} (target ${{ const.alert_below }})"
        severity: info

outputs:
  price: ${{ tasks.check.price }}