HumanLayer

Founded 2023 by CEO Dexter (Dex) Horthy, with Kyle Mistele as cofounder/CTO. YC-backed
(Y Combinator, Pioneer Fund, angels — $3M+ cumulative funding reported by mid-2026).

What it does

Started as an open-source Python toolkit giving AI agents a safe way to request human
approval before taking consequential actions (tool-based and asynchronous human-in-the-loop
workflows, working across OpenAI/Llama/Claude and frameworks like LangChain/CrewAI). That
approval layer expanded into a full coding-agent orchestration product.

CodeLayer

Open-source IDE (private beta since 2025) for orchestrating AI coding agents on large,
complex codebases — keyboard-first, supports parallel Claude Code sessions, and structures
work around a Research → Plan → Implement loop: research the codebase, produce a
human-reviewed plan, then execute, compacting context into reusable artifacts with human
checkpoints between phases. As of Aug 2026, reported thousands of engineers using its
open-source workflows, from YC startups to Fortune 500 companies.

Ideas the company is known for

• Loop Engineering — Kyle Mistele’s “Loop Engineering from First
  Principles” (AI Engineer, 2026-07-25) frames agent coding loops as a control-theory
  system: a sensor detects deviation from a desired codebase state, a controller selects a
  bounded intervention, an actuator (a CLI coding agent) implements it, and the result is
  evaluated — favoring small, reviewable PRs over unbounded code generation (“the 40,000-line
  PR problem”).
• 12-Factor Agents — Dex Horthy’s widely-cited framework treating agent reliability as an
  engineering problem: agents as conventional software augmented by narrow, well-scoped model
  decisions; small focused loops (5-10 steps, <100 tools) rather than one generalist agent.

See Also

• Loop Engineering
• Atomic (Bastani) — an unrelated company’s (Bastani Inc.) coding-agent runtime built on the same “small bounded step, verify, proceed” philosophy