An Obsidian Sync Built Around the Merger I Already Had
VaultLink: self-hosted Obsidian sync. Edit in any editor, online or off, then come back to a converged vault. The app that justified reconcile-text.
Engineering notes
Andras Schmelczer, software engineer. Writeups of finished projects, with the tradeoffs left in.
Most started because I couldn't yet do the thing: an 8-bit ALU, a mobile GPU, a single static HTML file, a cross-language ABI. The About page covers the patterns I keep returning to.
Latest Articles
All 22 articles-
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Backing Up Running Databases Without Stopping Them
A Bash container around BorgBackup. BTRFS snapshots give atomic consistency, numeric env vars give multi-target 3-2-1, the loop is sleep not cron.
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A Physics Practice App for the Hungarian Érettségi
A static jQuery site I built in high school to drill past exam questions. 659 questions, a decade of past papers, still online and still used.
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25 Million UK Property Rows in a Single Rust Process
Notes on perfect-postcode.co.uk. Every numeric feature is u16-quantised in a row-major array, so filter eval is two integer compares per row.
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An E-Ink Photo Frame That Sleeps When the House Is Empty
A Pi, a 6-colour e-ink panel, and a self-hosted Immich library. Photos picked by date and favourites, gated on Home Assistant presence, Atkinson-dithered.
Selected Projects
All projects-
Fleeting Garden Article
A single-file WebGPU drawing toy. Your strokes seed a swarm; nine numbers per vibe give each preset its personality.
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Frame Article
A LAN-only e-ink photo frame. Pulls from self-hosted Immich, gated on Home Assistant presence, Atkinson-dithered to 6 colours, no cloud.
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Perfect Postcode Article
A UK property-intelligence map. ~25M historical transactions, ~150 features per row, all u16-quantised in RAM, served from a single Rust binary.
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VaultLink Article
I refuse to give up the editor: Obsidian, Vim, VS Code, sed. Self-hosted sync that survives all four, built on reconcile-text underneath.
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reconcile-text Article
One Rust core, three packages. Merges Markdown notes from three editors I don't control, with no operation history. Never emits markers.
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GreatAI Article
One decorator on a Python function turned it into a deployed ML service. MSc thesis with a survey to back the API choices.
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SDF-2D Article
A browser 2D ray-tracer tuned for the phone in your pocket. Tile-based passes, deferred shading, shaders generated per scene and device.
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decla.red Article
Browser multiplayer where the client and server linked the same TypeScript rules module. Concurrency bugs you can't have are bugs you don't have.
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Ad Astra Article
A handheld game built from a custom PCB up: ATtiny85V, OLED, IR, EEPROM. 8-bit ALU at 8 MHz, 50 FPS floor.
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Life Towers Article
A multi-device goal tracker. The trie underneath made the sync diff free; the towers were just the UI.
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Cooling System Simulation Article
A live cooling-plant simulator for a PLC cybersecurity event. Flow as graph traversal and heat as a matrix solve: two passes instead of one PDE.