nika: v1
workflow:
  id: invoice-chaser
  description: "Ledger CSV → overdue filter → drafted reminders → human gate → drafts file"

model: ollama/qwen3.5:4b   # local · zero key · swap for groq/llama-3.3-70b (drafting is a fast-model job)

vars:
  ledger_csv: "./finance/invoices.csv"

tasks:
  ledger:
    invoke:
      tool: "nika:read"
      args: { path: "${{ vars.ledger_csv }}" }

  rows:
    with:
      csv: ${{ tasks.ledger.output }}
    invoke:
      tool: "nika:convert"
      args:
        input: "${{ with.csv }}"
        from: csv
        to: json
        has_header: true

  overdue:
    with:
      rows: ${{ tasks.rows.output }}
    invoke:
      tool: "nika:jq"
      args:
        input: "${{ with.rows }}"
        expression: 'map(select(.status == "overdue"))'

  drafts:
    with:
      overdue: ${{ tasks.overdue.output }}
    when: ${{ size(with.overdue) > 0 }}
    infer:
      prompt: |
        Draft one short, polite payment reminder per overdue invoice ·
        ${{ with.overdue }}
        Markdown · one section per client · firm but warm.

  approve:
    with:
      drafts: ${{ tasks.drafts.output }}
    when: ${{ with.drafts != null }}   # nothing drafted · nothing to approve
    invoke:
      tool: "nika:prompt"
      args:
        message: "Save the reminder drafts for sending?"
        default: false

  save:
    with:
      drafts: ${{ tasks.drafts.output }}
      approved: ${{ tasks.approve.output }}
    when: ${{ with.drafts != null && with.approved == true }}   # zero overdue → drafts skipped (null) · don't write nothing
    invoke:
      tool: "nika:write"
      args:
        path: "./finance/reminders-to-send.md"
        content: "${{ with.drafts }}"

outputs:
  overdue:
    value: ${{ tasks.overdue.output }}
    description: "The overdue rows the reminders were drafted for"

{"a":{"graph_format":2,"workflow":"invoice-chaser","nodes":[{"id":"ledger","verb":"invoke","tool":"nika:read","permits":["tool: nika:read"]},{"id":"rows","verb":"invoke","tool":"nika:convert","permits":["tool: nika:convert"]},{"id":"overdue","verb":"invoke","tool":"nika:jq","permits":["tool: nika:jq"]},{"id":"drafts","verb":"infer","model":"ollama/qwen3.5:4b","when":"${{ size(with.overdue) > 0 }}","permits":[]},{"id":"approve","verb":"invoke","tool":"nika:prompt","when":"${{ with.drafts != null }}","permits":["tool: nika:prompt"]},{"id":"save","verb":"invoke","tool":"nika:write","when":"${{ with.drafts != null && with.approved == true }}","permits":["fs.write: ./finance/reminders-to-send.md","tool: nika:write"]}],"edges":[{"from":"approve","to":"save","kind":"value"},{"from":"drafts","to":"approve","kind":"value"},{"from":"drafts","to":"save","kind":"value"},{"from":"ledger","to":"rows","kind":"value"},{"from":"overdue","to":"drafts","kind":"value"},{"from":"rows","to":"overdue","kind":"value"}]},"engine":"0.105.0"}

showcase · tier 2 · business

Invoice chaser

jq filters the overdue rows out of the CSV, reminders get drafted, and a human gate sits before anything is saved.

Friday’s awkward chore shrinks to reading the drafts and typing yes. · conformance-gated in nika-spec ↗ · re-proven at every push

The whole file

6 tasks · 6 waves · the plan falls out of the bindings, nothing is scheduled by hand.

t2-invoice-chaser.nika.yamlsource

1nika: v12workflow:3  id: invoice-chaser4  description: "Ledger CSV → overdue filter → drafted reminders → human gate → drafts file"56model: ollama/qwen3.5:4b   # local · zero key · swap for groq/llama-3.3-70b (drafting is a fast-model job)78vars:9  ledger_csv: "./finance/invoices.csv"1011tasks:12  ledger:13    ◆invoke:14      tool: "nika:read"15      args: { path: "${{ vars.ledger_csv }}" }1617  rows:18    with:19      csv: ${{ tasks.ledger.output }}20    ◆invoke:21      tool: "nika:convert"22      args:23        input: "${{ with.csv }}"24        from: csv25        to: json26        has_header: true2728  overdue:29    with:30      rows: ${{ tasks.rows.output }}31    ◆invoke:32      tool: "nika:jq"33      args:34        input: "${{ with.rows }}"35        expression: 'map(select(.status == "overdue"))'3637  drafts:38    with:39      overdue: ${{ tasks.overdue.output }}40    when: ${{ size(with.overdue) > 0 }}41    ◇infer:42      prompt: |43        Draft one short, polite payment reminder per overdue invoice ·44        ${{ with.overdue }}45        Markdown · one section per client · firm but warm.4647  approve:48    with:49      drafts: ${{ tasks.drafts.output }}50    when: ${{ with.drafts != null }}   # nothing drafted · nothing to approve51    ◆invoke:52      tool: "nika:prompt"53      args:54        message: "Save the reminder drafts for sending?"55        default: false5657  save:58    with:59      drafts: ${{ tasks.drafts.output }}60      approved: ${{ tasks.approve.output }}61    when: ${{ with.drafts != null && with.approved == true }}   # zero overdue → drafts skipped (null) · don't write nothing62    ◆invoke:63      tool: "nika:write"64      args:65        path: "./finance/reminders-to-send.md"66        content: "${{ with.drafts }}"6768outputs:69  overdue:70    value: ${{ tasks.overdue.output }}71    description: "The overdue rows the reminders were drafted for"72

nika inspect · engine 0.105.0 · vendored graph, never re-derived

6 declared edges · 6 waves · the plan falls out of the bindings

try itopen in the playground guidethe walkthrough · docs verbinvoke verbinfer toolnika:read toolnika:convert toolnika:jq toolnika:prompt toolnika:write