Rostyslav Stekh

AI systems in production
Lviv, Ukraine

Audits · agents
Mentoring

Where the demo ends.

I test AI systems before your customers do.

Book a call · 30 minformer CTO · RAG for 10,000 users · 15 years in software

Not ready for a call? Checklist: 11 quiet failure modes of AI agents (PDF)

verify.log · live example

“He never throws ‘AI magic’ at a problem. He understands data, constraints, operations, and risks. His solutions are stable, explainable, and maintainable. When you need a system that works today and still works six months later, he’s the person you trust.”

What I’ve built

Python · FastAPI · PostgreSQL · AWS · LangChain and LangGraph · vector databases · React

When people call me

Sound familiar? Tell me what isn’t working.

Book a call · 30 min

What it seemed, what it turned out

Seemed:

the bot needed a better prompt.

Turned out: it was retrieving the wrong pieces of the documents. We changed how documents were split and the retrieval order, and didn’t touch the prompt. On the test questions the bot started answering correctly 9 times out of 10 instead of 7.

health startup, RAG

Seemed:

the team was slow at writing code.

Turned out: code waited days for review. One repository setting helped, not a new process. Review went from three days to one.

my current team, under NDA

Seemed:

delivery sales had been falling for five months.

Turned out: at one outlet the till booked 12 of 32 marketplace orders as payments on the chain’s own website. The channel was falling less than the system showed. The marketplace portal also showed both outlets offline for 12–14% of scheduled hours, about double the previous half-year.

café chain, point-of-sale data analysis, pilot

“He introduced a judge node to our agent architecture, which brought a meaningful improvement to output quality.”

What I do and what it costs

from $2,000 · one system

Express audit of one system

One bot, RAG system or agent. 30–50 checks on your real queries, retrieval and answers checked separately. A report: what was checked, what wasn’t, and what to fix first. A 45-minute walkthrough. Takes 3 working days. Sample report (PDF, fictional data).

from $5,000 · up to three components

Full product audit

Up to three components. 100+ checks your team keeps. Cost and response time, exposure to instructions hidden in your data, access rights, monitoring gaps. A 30/60/90-day plan and a walkthrough with your team. Takes about 2 weeks.

from $3,000 · your team’s workflow

AI in your team’s workflow

How your team writes code with AI: rules for agents, reviewing AI-written code, checks in CI. Interviews with 2–3 developers and a list of changes, so AI speeds the team up instead of adding debt. Takes about 1.5 weeks.

priced after scoping · for your task

Building an agent, RAG system or automation

For a specific business task. First we agree how we’ll measure success: on which examples, with what accuracy, cost and response time. Then I build and test it before launch. Takes from a few weeks.

Right now I’m running a pilot with a coffee-shop chain: an agent works with their point-of-sale data and helps find where money gets lost. First findings are in, one case below.

I give the exact price after a 30-minute call, once it’s clear how many systems are involved and what access I’ll have.

If we start a full audit or a build within 60 days of an audit, its fee is credited. So if you’re not sure where to start, start with the express audit.

A re-check of your fixes 2–4 weeks later is included in every audit.

The first three audits are 30% off in exchange for a testimonial and an anonymised case study.

How we work

  1. A 30-minute call

    Free. You tell me what isn’t working or what you want to build. I tell you honestly whether I can help.

  2. A proposal with no surprises

    Price and timeline are fixed before we start. If the scope grows, we talk first, then re-price.

  3. The work

    An audit takes 3 working days to 2 weeks. A build follows the agreed plan.

  4. Walkthrough and next step

    A report and a walkthrough with your team. Then your team fixes things on its own or with me, in which case the audit fee is credited.

Who it’s for

A good fit if

  • Your AI feature is in production or about to be, and you need to know whether you can trust it.
  • Your team writes code with AI and doesn’t want to pile up debt.
  • You need an agent or RAG system for a specific task, with results you can measure.

Not a fit if

  • You need a slide deck about AI strategy with no system to verify.
  • You need a quick demo that isn’t meant to go to production.
  • You need a promised result before anything has been checked.

Questions

What exactly is in the report?

A table of checks with the result of each. Real queries where the system gets it wrong, and the cause behind each type of error. What wasn’t checked and why. What to fix first. The report comes as a PDF, with the checks your team can rerun after every change and the plan as a CSV for your task tracker. See the format: sample report (PDF; the company and data are fictional).

Do you work under NDA?

Yes. Most of my projects are under NDA, which is why there are no client names here.

Who does the work?

I do, myself, with no subcontractors.

What access do you need? Do you see my customers’ data?

The minimum: access to the bot or API in a test environment, 30–50 typical queries (anonymised is fine) and logs, if you have them. I don’t need access to your customers’ personal data. If the data is sensitive, we sign the NDA before we start, and I can work inside your infrastructure.

Remote? Which language?

Yes, remotely, I’m based in Lviv, Ukraine. English or Ukrainian.

What if the audit shows everything is fine?

You get a report of exactly what was checked, plus checks your team keeps and can run after every change.

What if the problem isn’t AI?

I’ll say so. In one of the cases above, a repository setting helped, not a new model.

Mentoring

An engineer growing into AI? A review of your AI project, or Career Inbound, an 8-week course I run with recruiter Oksana Holubets (in Ukrainian).

Tell me what isn’t working.

Book a call · 30 min

I write about what breaks: the Telegram channel “Why it breaks” (in Ukrainian) and LinkedIn.