Exploring the frontiers of language models, agents, and software design.

A collection of notes, essays, and technical deep dives by Ivan Leo.

Previously built general agents for knowledge work at Manus (acq by Meta). Embarking on a new adventure soon.

Featured Series

Building an Agent

A comprehensive series on building AI coding agents from scratch, covering everything from basic tool integration to advanced features like agentic search and subagents.

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1 PartsIn Progress

LLMs From Scratch

Working through Stanford's CS336 and documenting what I learn at each step — from tokenization to training.

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Latest Articles

ET Phone Home

Deploying our agent on Telegram with ngrok so it can report back

Feb 24, 2026·Openclawd From Scratch

It's alive!

Allowing an agent to modify itself with tools

Feb 23, 2026·Openclawd From Scratch

The Lay of the Land

Breaking down OpenClaw-style agents and the roadmap for building one from scratch

Feb 22, 2026·Openclawd From Scratch

Compiling IR to NFA

Turn regex IR into a graph-based automaton for fast next-step lookup

Feb 9, 2026·Structured Outputs From Scratch

Building our FSM

Going beyond a simple regex to an FSM for quick lookups

Feb 8, 2026·Structured Outputs From Scratch

Pydantic to Regex: Compiling JSON Schemas for Structured Outputs

Build a recursive JSON Schema-to-regex compiler from first principles

Feb 2, 2026·Structured Outputs From Scratch

Know when to let the model cook

Taste is all that matters.

Jan 18, 2026

How I Broke Into AI Without a Roadmap

The messy, fast-changing path that took me from front-end engineering to LLMs.

Jan 12, 2026