Przemysław Zalewski

AI-native senior full-stack engineer · available November 2026

I ship products with AI agents, under rules, and I measure what shipped

Fifteen years of shipping software, nine in TypeScript, React and Node.js. I built agentic systems before they were fashionable and today an agent opens about a third of my team’s pull requests. If your roadmap still slips with Claude Code in the building, that gap is my job.

Available from November 2026 · Wrocław, Poland (CET), remote

New: AI in your company, from pilot to production

Przemysław Zalewski
  • “someone you can always count on”public LinkedIn recommendation
  • “a true bias for action”client CTO, on LinkedIn
  • 15+ yearsshipping software
  • Free call, no pitch deck30 minutes, then you decide

The stack I ship with

  • TypeScript
  • JavaScript
  • React
  • Next.js
  • Node.js
  • Cloudflare
  • PostgreSQL
  • PostHog
  • Electron
  • Docker
  • GitHub
  • Anthropic
  • Stripe
  • Expo
  • .NET
  • MCP

Does this sound familiar?

Four situations I get hired for

The agents are fast and the codebase is on fire

Claude Code and Codex produce ten times the output and ten times the mess. Nobody owns the rules, the tests or the review. Every week adds velocity and debt in equal measure.

I write the rules the agents work under, put lint and test gates in CI, review what comes out and disclose what was AI-assisted. You keep the speed.

How I run agents

The MVP was vibe-coded and now there are customers

A demo became a product. No tests, no analytics, secrets in the repo, a deploy that only one laptop can run. Each new feature breaks two old ones.

A one-week audit with findings you can act on, then a rescue sprint: tests around the money paths first, then the three biggest risks, then a deploy anyone can run.

Rescue and take-over

Nobody can say which feature moved which number

The dashboard exists, the tracking plan does not. Leadership asks and engineering guesses. AI without analytics is running blind, only faster.

PostHog from day one: a tracking plan per feature, a first-party proxy so the data arrives, dashboards leadership reads without asking.

Measure what ships

You want your product to be usable by agents, not only people

Customers ask for an MCP server, an API agents can call safely, an AI feature with a real evaluation loop. The team has the API and none of the rest.

An agent and MCP readiness audit, then the server: narrow tools, existing auth, adoption measured per client from the first merge.

Agent and MCP readiness

How we can work together

Three shapes of engagement, no prices on the page

Scope first, then a number in writing. The call is free either way.

1 week

Agent & MCP readiness audit

Your API, auth, tool surface, evaluation data and analytics, read by someone who has shipped this. You get a written report: what an agent could safely do today, what needs work, a plan with milestones.

  • Findings you can act on
  • A plan with milestones
  • A go or no-go you can defend
Book a free call →

3 to 6 weeks

AI feature or rescue sprint

One outcome, shipped and measured: an MCP server, an AI feature with an eval loop, a vibe-coded MVP made production-ready, a Next.js app that stops hurting.

  • Something to touch in week one
  • Tests around what matters
  • A tracking plan and dashboard
Book a free call →

2 to 3 days a week, 3 months minimum

Fractional tech lead

Inside your team: architecture, code review, the rules for coding agents, hiring screens, the estimates. Your team keeps shipping, I keep the direction and the quality bar.

  • Review of every PR
  • Agents under rules
  • Numbers at the weekly call
Book a free call →

Services

Pick the technology. Each page has a live demo.

Front-end

Platform, delivery & product

AI, data & specialties

How I work with AI

AI-native means rules, review and numbers

Rules the agents cannot skip

Mechanical checks over written guidelines: lint and test gates for security, API surface and CSP. The model suggests, the criteria decide.

A human review on every PR

About 30% of merged pull requests across two products in 2026 came from an agent. I reviewed about 85% of them. The responsibility stays with me.

Quality measured, never assumed

Best-of-n, LLM-as-judge, scoring against fixtures. Many models compared across releases, swapped when the numbers say so.

Disclosed, so trust survives

AI-assisted work is labeled as such, to the team and to users where it matters. Agents are teammates, not ghostwriters.

~30%of merged PRs in 2026 opened by an AI agent, ~85% reviewed by me
~40×more commits year over year with agents under enforced rules
4months from first commit to the App Store
15+years shipping software

Proof

Three things I shipped with agents in the loop

Problem, what I did, result. Client names only where I am allowed to use them.

Patriot Mail: from first commit to the App Store in four months

The problem
A greenfield AI-native email client for web, iOS and macOS had to reach real users fast, pass Google’s CASA Tier 2 security assessment and work for older people.
What I did
I was the principal engineer. I wrote the delivery plan, shaped the product vision and treated prompt injection through untrusted email as a design constraint before any model touched a mailbox. CASA and OWASP ASVS controls became a Playwright suite that runs on every pull request. WCAG 2.2 AA sits behind an automated axe gate.
Result
Public App Store release in four months. CASA Tier 2 passed and the yearly questionnaire turned into a check on every PR. Text scaling to 200% and a calm-email mode shipped for older users.

4 months CASA Tier 2 WCAG 2.2 AA Open ↗

See also: SaaS & MVP · Mobile & desktop apps

An AI coding agent as a team member, under enforced rules

The problem
Coding agents produce ten times the output and ten times the mess. A team of four wanted the speed without a slop swamp on main.
What I did
I authored the rule set shared by Claude Code and Codex: mechanical checks over written rules, lint and test gates for security, API surface and CSP, agents working on main with hooks, every PR reviewed by a human, AI-assisted content disclosed as such.
Result
In 2026 the agent opened about 30% of merged pull requests across two products and I reviewed about 85% of them. My own output went from under 1,000 to 5,000+ commits a year.

~30% PRs by agent ~85% reviewed 5,000+ commits/yr

See also: AI & agents · Full-stack & custom software

An MCP server from first merge to first external users

The problem
Users wanted to log time from their AI assistants. The API existed, the agent surface did not.
What I did
I set the tool surface, removed destructive tools, routed every operation through the existing REST controllers so an agent gets no wider access than a person, and instrumented adoption per client in PostHog from day one.
Result
First external users within weeks. A bot-protection rule that rejected MCP clients by user agent was found and removed the same day because the dashboard showed it.

MCP OAuth adoption dashboard

See also: AI & agents · PostHog & product analytics

One foot in the door

Not ready for a project? Start smaller.

Two ways to see how I work before you commit to a sprint. Fixed scope, a number in writing after a short call.

Codebase audit, one week

I read the repo, CI, tests, security and the parts the team avoids. You get a written report with findings ranked by risk, a plan with milestones and a go or no-go you can defend. I have run this for a large software house before its clients saw the code.

Code review of one pull request or one module

Send me the diff that worries you. Within a few days you get line-level comments, the three things I would change first and whether I would merge it.

Ask about an audit Free 30-minute call first. If an audit is the wrong tool, I say so on the call.

How it works

Three steps from this page to a running project.

  1. 1

    A 30-minute call

    You describe the product and the problem. I ask the questions I would ask on day one. If I am not the right person, I say so and point you to someone who is.

  2. 2

    Scope in writing

    A short written plan follows: what we build first, what we measure, how we work together and what it costs. No slide deck.

  3. 3

    Something to touch in week one

    The first slice ships in the first week: deployed, measured, reviewable. From there the work is paced by what the numbers say.

Fit check

Is this a fit?

A good fit when

  • You need a senior who owns delivery, not a pair of hands
  • The product has to ship and be measured, with or without a product manager
  • A solo engagement or a team of up to four
  • TypeScript, React, Node.js, Cloudflare, Postgres, PostHog

Probably not when

  • A program that needs a ten-person vendor team
  • A stack built around Java, Python or a cloud I do not sell
  • Body leasing by the hour with no say in how the work is done
  • A start before November 2026

FAQ

Questions people ask before they book

What does AI-native mean in practice?
Coding agents are team members with rules, not autocomplete. I write the rule set they work under, keep lint and test gates in CI, review every pull request and measure the result in PostHog. The AI and agents page shows the agent that runs on this site, with its tool calls visible.
Can you take over a vibe-coded codebase?
Yes. First a one-week audit with findings you can act on, then tests around the flows that make money, then the three biggest risks. The site keeps running throughout. The full-stack page describes the take-over process and the Next.js page has a live demo of the most common performance problem.
Remote, time zones, language?
Remote from Wrocław, Poland (CET). I have worked across a nine-hour gap with a US client and daily with UK teams. English is my working language, Polish is native. This site exists in both.
Teams or solo?
Both. Solo for audits and sprints, as fractional tech lead for teams of up to four engineers, including the agents. For larger programs I will tell you on the call and point you to a team.
Contract form?
B2B contract or employment, from November 2026. Invoices in EUR, USD or PLN. Scope and price in writing after the first call, never on this page.
How soon can you start?
November 2026. Book the free call now and the scope will be ready on day one. My resume has the timeline.
Przemysław Zalewski

Let’s find out in 30 minutes

A free 30-minute call. You bring the problem, I bring questions. No prices on this page because scope comes first.

If I am the wrong person I will say so on the call and point you to someone better.

After you book: a calendar invite, then the call. Nothing else to fill in.

Available from November 2026 · B2B contract or employment · Wrocław, Poland (CET), remote