What this is
A running log of the things I like tinkering with: writing code, electrical engineering, and mathematics. Some of it's handy, some of it's just me figuring things out in the open.
Background
A backend and distributed systems engineer working the full depth of the stack: storage engines, lock-free concurrency and compilers, and the services, queues and data pipelines built on top of them. A long earlier career in consumer software taught me what the upper layers need from the lower ones, and a background in UX design means I usually take on the information architecture and interface structure as well. Having founded a product company, run it single-handedly and sold its core engine, I assess architecture decisions on commercial as well as technical grounds.
Essays
Valentin Radu · 2026 ·
Valentin Radu · 2026 ·
Career highlights
MotionTools, at MTribes
One of three engineers hired to build the platform, where I owned the architecture from the browser down to the services: queue-backed service boundaries, the write-behind path for live vehicle telemetry, and the dispatch model. The company later broadened it from a specialised courier app into a platform, on that same architecture rather than replacing it.
Cadenza, at Codewise Systems
Founded the company and took Cadenza to Top 10 in Music on the US App Store. Researched and implemented its pitch detection, held to roughly ±2 cents against a reference piano tuner and reliable on low notes, where competing spectral tuners read an octave high. The engine was acquired in 2017 and shipped inside the buyer's product.
Trip Journal, at iQuest
Sole UX designer on the product: Travel category winner at Google's Android Developer Challenge II and Excellence in Design at Mobile App World London, with nearly 300,000 users. The exposure converted into new client contracts, Jaguar among them.
Outside of work, OSS
Pent
Runs untrusted processes under restricted filesystem and network access. Linux sandboxing primitives, distributed through a Homebrew tap.
formalang and formawasm
A statically typed, declarative language designed to be embedded in Rust applications. Its compiler frontend ships as fvc; formawasm lowers the typed IR to WebAssembly components.
clipto
Clipboard daemon for Linux, bridging tmux on a TTY with Wayland.
Helm
Graph-based router for SwiftUI.
swift-toledo
Dependency injection with statically generated resolvers, so the wiring is checked at compile time.
Technical skills
Languages
Rust, Python, Swift, C, SQL, TypeScript, shell
Backend
HTTP and REST API design, auth, background jobs and queues (Celery, Redis), caching strategy, schema design and migrations, websockets and real-time transports, BFF
Databases and storage
Postgres and PostGIS, Redis, SQLite; indexing and query tuning; storage internals: B+ trees, shadow paging, memory mapping, page layout
Data and ML
Ingestion and ETL pipelines, canonicalization, entity resolution, embeddings, vector search and ANN indexes, product quantization, retrieval, self-hosted model serving, fine-tuning, ONNX
Systems
Linux and Unix internals, processes and syscalls, sandboxing, concurrency, async I/O, lock-free data structures, memory management, profiling, compilers and WebAssembly
Testing and correctness
Unit, integration and snapshot testing, property-based testing, fuzzing, concurrency model checking, fault and crash injection, benchmarking
Tooling and delivery
Git, CI (GitHub Actions), Nix, release automation, structured logging and observability
Design
UX and information architecture, wireframing and prototyping, design systems, interface structure
Leadership
Architecture and roadmap ownership, contractor sourcing and interviewing, scoping and delivery cadence
Apps and frontend
React, HTML and CSS; iOS and macOS, SwiftUI, real-time audio (Core Audio), OpenGL
Experience
Principal engineer
Kinoto · Porto · 2023–Present
Software engineer
xymatic · Berlin · 2022–2023
Software engineer
Audyo · London · 2021–2022
Independent R&D
2019–2021
Software engineer → Solutions architect
MTribes · Hamburg · 2017–2019
Founder
Codewise Systems · Cluj · 2011–2017
Software engineer
Endava · Cluj · 2014–2016
UX designer
iQuest Group · Cluj · 2009–2011
Freelance
Cluj · 2005–2009
Education
Studied Computer Science and Philosophy
Babeș-Bolyai University · Cluj · 2005–2009
Awards
Google Android Developer Challenge II
Trip Journal · Travel category · 2009
Excellence in Design and Best Paid-For App
Trip Journal · Mobile App World, London · 2010
All Around Best App Ever
Trip Journal · 360iDev
Dev log
Ten predictions and observations from the AI era
Jul 2026Ten predictions and observations from the beautiful madness of the AI era. The good and the bad: moats, the supervisor economy, regulation as the real bottleneck, and the end of universities as we know them.
Back to wires: Introduction
Updated Jun 2026A complete, ground-up course in electrical theory and code: how it's built, the shape of each lesson, and the ground it covers across eight areas from fundamentals to maintenance.
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- 1. Back to wires: Introduction (above)
- 2. Back to wires: Direct current
- 3. Back to wires: DC circuit analysis
- 4. Back to wires: electric and magnetic fields
- 5. Back to wires: the electromagnetic field, light, and relativity
- 6. Back to wires: capacitors, inductors, and the circuits they shape
- 7. Back to wires: alternating current
Anthropic and the caravel problem
Jun 2026In 1500 a country of a million people invented the ship that opened the world, got rich beyond its size, and then lost everything to latecomers with deeper pockets. Frontier AI labs are sailing the same caravel. Why the model was never the moat, and the two narrow ways out.
npm install and pray. Axios and TanStack, 2026.
May 2026Two npm supply chain attacks in early 2026: the Axios compromise by Sapphire Sleet and the Mini Shai-Hulud worm by TeamPCP. What happened, how to check if you were hit, how to harden, and an honest look at how Pent would have mitigated these.
Vector search: The problem
Updated May 2026Why nearest neighbor search is easy in 1D, manageable in 2D, and falls apart in 768D. The first post in a series on vector search, working from the problem itself before the algorithms.
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- 1. Vector search: The problem (above)
- 2. Vector search: Small worlds
- 3. Vector search: On disk
- 4. Vector search: Quantization
AI and technical writing
May 2026Almost every public article online is written with AI assistance now. So are the articles on this site. A note on how I write now, and why.
I built a compiler frontend with Claude's help. A retrospective.
Mar 2026A writeup of building formalang, a compiler frontend, with Claude in the loop. The actual workflow, what it cost in time and reading, where the agent helped most, and a final scorecard.
Self-hosting Devstral Small 2 on a 48 GB GPU
Dec 2025Deploy Mistral's Devstral Small 2 (24B coding model) with vLLM on a 48 GB workstation GPU or rented cloud instance, then connect it to OpenAI-compatible agentic clients (Cline, Continue, OpenCode).
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The exponential thread: The puzzle
Updated Oct 2023Starting from a 3rd-grade equation and arguing that it is the entry point to the deepest unification in modern mathematics. e, ln, sin, cos, complex exponentials, matrices, and Lie groups all turn out to be the same object viewed from different angles. The first post in a nine-part series.
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- 1. The exponential thread: The puzzle (above)
- 2. The exponential thread: Why e is natural
Rust for Swift devs: The type system
Updated Nov 2025Coming to Rust from Swift is a shorter transition than most assume. The first post in a series, starting with the type system: structs, enums, traits, generics, and the dyn/impl distinction.
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- 1. Rust for Swift devs: The type system (above)
- 2. Rust for Swift devs: Error handling
- 3. Rust for Swift devs: Memory and ownership
- 4. Rust for Swift devs: Lifetimes
- 5. Rust for Swift devs: Concurrency
- 6. Rust for Swift devs: Tooling and interop
AWS Lambda + Rust
Mar 2019Deploying Rust on AWS Lambda in 2026: how the toolchain has changed since 2019, and what a minimal, idiomatic setup looks like today.