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Anton GoncharovAI systems developer
RUEN

Go service · queue · approval

Purchasing agent

An agent that buys coffee on its own must not lose a request halfway through, and must not send it twice if the process dies. Here a request is a job in a River queue. It stops for approval, and “Cut off the send” drops the step: the retry finishes the same order, not a new one.

Scenario: Zerno, a fictional roastery: green coffee of three origins and a local supplier.

Demo screenshot: Purchasing agent

Open the demo

Open the app

The supplier is local. The queue and the steps are a Go service and PostgreSQL.

The app runs in your browser: nothing is sent to a server.

What the demo shows

  • Request steps: stock, draft, approval, send

  • If there are not enough kilograms, the request is refused and the tape says how much was in stock

  • Sending does not start until the buyer confirms the draft

  • A cut-off send returns the same job to the queue

  • The supplier order number is written once

How to try it

  1. Buy Ethiopia

    “Buy 30 kg of Ethiopia”. The request checks stock and stops at the draft.

  2. Confirm

    “Confirm sending” — one order number goes to the supplier.

  3. Cut off the send

    A new request, then “Cut off the send”. The tape shows the cut-off and then the same order, without a second number.

  4. Ask for too much

    “Buy 50 kg of Colombia” — 6 kg are in stock, so the request is refused.

No paid neural networks

The supplier is a local database row, with no mail and no payment. The queue is real: each step is a River job in PostgreSQL, and it survives a cut-off.

The demo runs without OpenAI, YandexGPT or GigaChat API keys. Wherever a production system calls a model, there’s a local stub with the same interface — so the demo is free, always available and never makes things up.

What a production project adds

  • The supplier is MoySklad, 1C or email, rather than a row in the demo database
  • The approval goes to the buyer in Telegram
  • The same queue for other long-running agents: contracts, payments, exports
  • A separate worker that can be stopped without stopping the gateway

Stack

  • Go
  • River
  • pgx
  • sqlc
  • goose
  • PostgreSQL
  • slog
  • React 19

Want the same for your business?

Tell me about your task — I’ll tell you what from the demo fits, how long it will take and what I’ll need from you.

Message me on TelegramSend a request

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