HALCYSenior EngineerApplication / Alex Kostyniuk

I have been at AMFG six years, junior to team lead. It is a manufacturing platform, factories plan and run production on it. I lead three engineers and still write code every week.

Tech/Team Lead · TypeScript across the stack · Stockholm, hybrid

Alex Kostyniuk

Traveller 001 / Candidate

Shared itinerary

4 editors, live

  • Lofoten, late June

    locked

    Mon

  • Flights held, 4 seats

    held

    Mon

  • Cabin in Reine

    edited

    Tue

  • Hike + kayak day

    open

    Tue

  • Ferry back to Bodø

    ok

    Wed

Four people editing one plan. That is the hard part.

Synced

Why we're a strong match

My Open Source projects

Shipped and public

Why Halcy should hire me

Two people editing the same thing
I built a Gantt scheduler that several planners drag around at the same time, synced live. I got the conflicts wrong a few times before I got them right, so I know what deciding who wins actually costs.
Our CI went from 20 minutes to 4
Our CI went from 20 minutes to 4 once I stopped the tests fighting over the database. Nobody had to be told to push smaller changes after that, they just did.
eevee, a PR review agent I built
eevee is mine: an agent on Vercel's eve framework that reviews pull requests, rates how safe each one is to merge, and learns from what I correct. It has its own eval suite, because a prompt that matters needs a number that moves in CI.
I got a whole team using AI
I ran the workshops, set up the tooling, and sat with people until it stuck. At work I built our MCP server and public API so agents can drive the product from outside it. A vaguely named tool costs more in retries than the model costs in tokens.
Postgres past the ORM
Hundreds of tables, multi-tenant, and pgvector for similarity search on 3D models. Query plans, indexes, and locking are things I reach for deliberately rather than look up during an incident.
0→1, then earned versions
Everything above went from a blank editor to something strangers use, decided and shipped on my own time. Leading three engineers has not taken me out of the code, and each of those projects changed after real usage rather than a spec.

Why I want to join Halcy

An AI startup solving something real
I want to work where AI is the mechanism rather than a feature someone bolted on. Turning a vague group idea into a booked trip is genuinely a cool orchestration problem.
Shared state with money in it
Four people editing one trip, two of them booking the same slot from different timezones. I want to work on that problem.
I have lost trips to group chats
Plans everyone wants and nobody books. Fixing that is worth doing.

How I work.

I start with either a problem to solve or a business idea. I shape it around customer needs and technical realities, and look for a solution that can serve many customers instead of just one. Once the core is clear, I work with Design team on the experience, break it down into a focused story, and leave it ready for a developer or me to build.

How I develop features

  1. 01

    Start with an agent

    I always work with an agent. For bigger features or bugs that aren't obvious at first, I use specific skills to help it focus. For smaller tasks, I explain what needs doing and jump in.

  2. 02

    Scope the solution

    When the work needs a plan, I turn it into a detailed spec, including edge cases and what done looks like.

  3. 03

    Implement with agents

    Once the task is clear, I let one or more agents build the feature.

  4. 04

    Create feedback loops

    Browser Use, types, and tests help the agents see what they built and catch their own mistakes.

  5. 05

    Check manually

    I still open the feature and use it myself, from start to finish.

  6. 06

    Run an agent review

    I ask fresh agents to review the work and catch anything the first ones missed.

  7. 07

    Review the code

    Then I read the diff myself and fix whatever is left.

  8. 08

    Babysit the PR

    Finally, an agent watches CI and review comments until the PR is ready to merge.

Outcome

The result is a feature that has been planned, built, checked, and reviewed from a few different angles, usually in much less time.

HALCYSenior Engineer

Let's make a group trip feel like one decision.

Halcy × Alex

Continue to my portfolio

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