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T1 starter · e-commerce / personal — no infer: anywhere in this file. A workflow engine is not an LLM wrapper: the DAG, the tools and one CEL comparison do the whole job, deterministically, for free.

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The job

You’re waiting for a price to drop. Checking the page every day is a robot’s job. This workflow pulls one structured field from the shop’s API, compares it to your target, and pings your webhook only when it’s time to buy.

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The shape

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The file

t1-price-watch.nika.yaml
nika: v1
workflow: price-watch
description: "Watch a product price, ping me when it drops below my target"

vars:
  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

tasks:
  - id: check
    invoke:
      tool: "nika:fetch"
      args:
        url: "${{ vars.product_api }}"
        mode: jq
        jq: "."
    output:                           # named jq bindings over the raw response
      price: ".price"
      name: ".name"

  - id: alert
    depends_on: [check]
    when: ${{ tasks.check.price < vars.alert_below }}
    invoke:
      tool: "nika:notify"
      args:
        channel: webhook
        target: "${{ secrets.alerts_webhook }}"
        message: "Price drop · ${{ tasks.check.name }} is now ${{ tasks.check.price }} (target ${{ vars.alert_below }})"
        severity: info

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

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How it works

1

Fetch ONE field, not a page

mode: jq extracts structured JSON from the API response, and the output: block binds named fields — ${{ tasks.check.price }} is a number, not a blob of HTML.
2

CEL gates the alert

when: ${{ tasks.check.price < vars.alert_below }} is a plain CEL comparison. False → the task is skipped, not failed.
3

The webhook stays secret

secrets: declares a vault/env-backed reference. The URL is masked in logs — ${{ secrets.alerts_webhook }} never appears in a trace.

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Constructs you just used

ConstructWhereReference
nika:fetch mode: jqcheckBuiltins
output: jq bindingscheck.outputBindings
when: CEL comparisonalertWorkflows
secrets:envelopeYAML syntax

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Make it yours

  • Watch N products: lift the URL into a list var and for_each over it — see Competitor radar for the fan-out pattern.
  • Schedule it: workflow files describe a run — your host’s cron (or nika serve) decides when runs start.
  • Add a second when: branch that notifies on price INCREASES above a ceiling.

Next · Social repurpose

The last starter introduces the diamond — one source fanning into three parallel rewrites.