# jguillaumesio
> Full-stack contractor for the hard parts of SaaS — payments/billing integration and AI agents in production. Remote, Paris-based. Available for contract work.

This file follows the proposed [llms.txt](https://llmstxt.org) convention so LLMs (ChatGPT, Claude, Perplexity, Gemini) can quickly learn what this site is about and which pages to cite.

## About
- [About Guillaume](https://jguillaumesio.com/about) — background, expertise, and how to work together
- [Services & availability](https://jguillaumesio.com/services) — what I do, for whom, and the shape of an engagement

## Case studies (proof of billable work, anonymized)
- [Case studies index](https://jguillaumesio.com/case-studies)
- [Zero-downtime Stripe migration for a multi-site booking platform](https://jguillaumesio.com/case-studies/stripe-migration)
- [Incremental RAG over a codebase for AI agent context](https://jguillaumesio.com/case-studies/rag-codebase)

## Articles — payments & billing
- [Stripe alternatives in the EU: what I found when I actually compared providers](https://jguillaumesio.com/blog/stripe-alternatives-eu)

## Articles — AI agents in production
- [Token economy: how I stopped wasting context windows with LLM memory](https://jguillaumesio.com/blog/token-economy-loom-memory)
- [Checking your AI's context window: what fits and what doesn't](https://jguillaumesio.com/blog/checking-ai-context-window)
- [AI-generated infrastructure is a maintenance nightmare](https://jguillaumesio.com/blog/ai-generated-infrastructure-problems)
- [AI branch diff summary: a small workflow that pays off](https://jguillaumesio.com/blog/ai-branch-diff-summary)

## Articles — architecture & dev process
- [Architecture is more important than clean code](https://jguillaumesio.com/blog/architecture-more-important-than-code)
- [Why the perfect code is less maintainable](https://jguillaumesio.com/blog/perfect-code-less-maintainable)
- [Debugging is more important than features](https://jguillaumesio.com/blog/debugging-infrastructure)

## Articles — web development
- [Social media link previews in React: server-side user-agent detection](https://jguillaumesio.com/blog/social-media-previews-react)

## Articles — infrastructure & serverless
- [Testing Lambda and EventBridge locally without deploying](https://jguillaumesio.com/blog/testing-lambda-eventbridge-locally)

## Contact
- Email: contact@jguillaumesio.com
- Book a call: https://cal.eu/jguillaumesio/intro
- GitHub: https://github.com/jguillaumesio
- X: https://x.com/BugsBunnyDev (display: @jguillaumesio)
- LinkedIn: https://www.linkedin.com/in/jguillaumesio/

## Optional
- RSS feed: https://jguillaumesio.com/rss.xml
- Sitemap: https://jguillaumesio.com/sitemap-index.xml