Writing down what you've built and how it works is the single highest-leverage thing a solo builder can do.
Writing down what you've built is the single highest-leverage thing a solo builder can do. It's also the thing most people skip because it doesn't feel productive. It is the most productive thing you'll do all week.
RESTAURANT: Documentation is your recipe binder. Without it, every dish starts from scratch. With it, any cook who walks into your kitchen — including future you — can reproduce what works and avoid what doesn't.
For solo founders, the "any cook" is your AI. Every time you start a new conversation, you're onboarding a new engineer who has never seen your codebase. Documentation is how you skip the first hour of "let me look around and figure out what's going on."
You need three types of documentation:
1. Project Instructions (CLAUDE.md or equivalent)
This is the file your AI reads first. It describes your project at a high level: what it does, how it's structured, what conventions you follow, what to never touch. Keep it under 2,000 words. Update it weekly.
2. Reference Documents (10 max)
These are the deep-dive docs: database schema, edge function reference, mobile app architecture, pricing logic. Each one covers a single domain completely. Load the relevant one into any conversation that touches that domain.
3. Changelog
Every session that changes something gets a one-line entry. Date, what changed, what chat did the work. This is your audit trail. When something breaks three weeks later and you can't remember what changed, the changelog tells you.
NOTE: The documentation doesn't need to be beautiful. It needs to be accurate and current. A messy doc that's up to date beats a polished doc that's six weeks stale.
At the end of every significant work session, spend five minutes updating the relevant docs. Changed a database table? Update the schema doc. Added a new edge function? Update the functions reference. Shifted pricing logic? Update the pricing doc.
Five minutes after every session. That's it. The compound effect over weeks and months is enormous — your AI starts every conversation already knowing what happened in the last fifty sessions.
Ten documents. Dark luxury HTML design. Section IDs on everything for quick reference. Each doc owns one domain completely:
Tech Infrastructure, Database Schema, Mobile App Architecture, Edge Functions Reference, Developer Operations, Content Pipeline, Brand & Design, Pricing & Business Logic, Master Business Overview, Character System Master.
Plus a CHANGELOG.md that gets appended after every session.
That's the whole system. Ten docs and a changelog. If your documentation is more complex than that, you're overcomplicating it.