~/ overview

Production mobile apps that hold up under real conditions

I'm Stefan — a senior mobile engineer and former CTO. I build Flutter apps for iOS and Android and Web, with the Google Cloud systems behind them, and the AI inside all, for clients in Europe and the US. Ten years in, with apps live on both stores and websites today.

~/ evidence_config

stores:

iOS App Store, Google Play, Web hosting — still shipping updates

clients:

United States, European Union

regulated:

Dutch government programme, GDPR, ISO 27001, SOC 2

experience:

Ten years application development, six senior in Flutter

~/ method

The model is the easy part. What I build is everything around it that decides whether you can trust it.

Anyone can wrap a model in a chat interface, and that is where the demand is, so I will build it. But it is not the hard part and it is not what you are paying for. The hard part is what it costs per user, how the system behaves when it is slow or confidently wrong, what it is allowed to touch, and what happens the day it makes a mistake nobody catches. On a live trade business my agents draft the email and a person sends it, because a bad draft costs two seconds of reading and a bad send cannot be recalled.

fig.01 — every write passes all three gates, and lands in the audit log

Every model output is validated against a schema before anything acts on it.

A scoped capability, not an admin login.

~/ work_registry

project

what it is

what it proves

cosyra

an ai coding terminal that runs on a phone

ships real products

lsi

seven agents running a trade pipeline, none can press send

ai automation in production

pvo

a government platform where data could not leave the country

delivery under regulation

tek

wholesale ordering where price is an access-control problem

current us client work

~/ capability

MOBILE APPS

Flutter, iOS and Android, built to be maintained rather than demoed.

THE CLOUD SYSTEM

Google Cloud and Firebase, on your accounts, admin tooling included.

AI AUTOMATION

Agents with scoped permissions and a full audit trail.

REGULATED DELIVERY

GDPR, ISO 27001 and SOC 2 as architecture, not a checkbox — see services.

~/ terms

response:

Same day, including outside European hours

contact:

A direct line to the person building it

tools:

Jira, Linear, Notion, Monday

ownership:

Your accounts, your code, your IP from day one

pricing:

Fixed price, scoped up front

~/ writing

2026-08-09

Firestore security rules are not filters

Firestore security rules reject a query, they never narrow it. Why a scoped list throws, four predicates worth reusing, and what a membership check costs.

Cloud & Backend

2026-08-09

Autonomy is a dial, not a switch

AI agent autonomy isn’t on or off. Four positions on the dial, the reversibility test that decides which one you need, and what each level costs.

AI Agents & Automation

~/ init_sequence

What are you building?

Thirty minutes is usually enough to work out whether I am the right person. If I am not, you get a straight answer and a suggestion of where to look instead.