# parkjunwoo.com

> Architect & writer. Designing systems from first principles — in code, knowledge, physics, and between people.

This site publishes technical essays and open-source toolchain documentation for Reins Engineering — an approach that gives AI coding agents deterministic contracts and blocks progress when contracts are violated.

## Core Content

- [Reins Engineering](https://www.parkjunwoo.com/reins.md): Index of all Reins Engineering articles and tools

## Concept

- [Reins Engineering — AI with Reins](https://www.parkjunwoo.com/opinion/reins-engineering.md): Harness is a fence. Reins steer with deterministic contracts, lock with ratchets, separate decisions from implementation.
- [Why Coding Agents Work and Why They Break](https://www.parkjunwoo.com/opinion/why-agents-work-and-break.md): The same model hallucinates in web chat but ships features in a coding agent. The topology changed, not the model.
- [Feedback Topology Over Model IQ](https://www.parkjunwoo.com/opinion/feedback-topology.md): The same model stalls at 40 or completes all 527. The difference is feedback structure, not model size.
- [AI Sycophancy Bias Is a Business Feature](https://www.parkjunwoo.com/opinion/sycophancy-is-a-feature.md): Sycophancy is not a bug. It is RLHF's mathematical inevitability. LLM-as-Judge is structurally impossible.
- [Agent Operable Codebase](https://www.parkjunwoo.com/opinion/agent-operable-codebase.md): When a file has 20 functions, agent performance drops 30-85%. The office must be turned into a factory.
- [Building Agent-Operable Systems](https://www.parkjunwoo.com/opinion/building-agent-operable-systems.md): 60-80% of enterprise IT budgets guard locked legacy. Freeze bugs first with Hyrum's Law, then transform.

## Pattern

- [Ratchet Pattern](https://www.parkjunwoo.com/tech/ratchet-pattern.md): A mechanical lock that prevents backward drift in AI agent workflows. Ratchet code never allows regression below a passed verification level.
- [Ratchet Code That Exploits IFEval](https://www.parkjunwoo.com/tech/ifeval-ratchet.md): Combine IFEval instruction-following with deterministic feedback for convergent code generation.
- [Hurl Stops Vibe Coding Drift](https://www.parkjunwoo.com/tech/hurl-vibe-coding-drift.md): Declare API contracts in plain text with Hurl and lock with a ratchet.

## Toolchain

- [yongol](https://www.parkjunwoo.com/tech/yongol.md): Cross-layer SSOT validator & codegen. 9 spec types, one CLI. Compresses AI context ~10x.
- [filefunc](https://www.parkjunwoo.com/tech/filefunc.md): One file, one concept. LLM-native Go code structure convention + 22-rule validator.
- [huma](https://www.parkjunwoo.com/tech/huma.md): Hurl Master — ratchet tool that drives AI agents to write wall-to-wall Hurl tests. scan, next, write, verify.
- [codistill](https://www.parkjunwoo.com/tech/codistill.md): Static analysis that extracts OpenAPI, DDL, and SQL skeletons from existing Go+Gin, NestJS, FastAPI code.
- [tsma](https://www.parkjunwoo.com/tech/tsma.md): LLM-driven test extraction from legacy code — branch coverage oracle.
- [Feature Chain](https://www.parkjunwoo.com/tech/feature-chain.md): One operationId extracts the entire full-stack scope.
- [toulmin](https://www.parkjunwoo.com/tech/toulmin.md): Toulmin argumentation rule engine for Go. Rules are functions, verdicts via h-Categoriser.
- [SSaC](https://www.parkjunwoo.com/tech/ssac.md): Service Sequences as Code. Declarative service logic in Go comments, generated implementation.
- [whyso](https://www.parkjunwoo.com/tech/whyso.md): Extract the "why" behind every file change from Claude Code sessions.

## Practice

- [GEO: How to Get AI to Cite Your Content](https://www.parkjunwoo.com/tech/geo-for-ai-visibility.md): Infrastructure, sitemaps, Wayback Machine, citations, and social activity — five axes for AI visibility. GEO paper shows +41% for quotations, +32% for statistics, +30% for citing sources.

## Open Source

- [yongol on GitHub](https://github.com/park-jun-woo/yongol)
- [filefunc on GitHub](https://github.com/park-jun-woo/filefunc)
- [toulmin on GitHub](https://github.com/park-jun-woo/toulmin)
- [huma on GitHub](https://github.com/park-jun-woo/huma)
- [codistill on GitHub](https://github.com/park-jun-woo/codistill)
- [tsma on GitHub](https://github.com/park-jun-woo/tsma)
- [whyso on GitHub](https://github.com/park-jun-woo/whyso)
- [ssac on GitHub](https://github.com/park-jun-woo/ssac)

## Author

Park Jun Woo — mail@parkjunwoo.com — https://www.parkjunwoo.com/about/