I’ve tried a lot of note-taking systems. Most of them died within a month. The current setup has been running for over a year and I still use it every day. Here’s what makes it different.
Why a second brain at all
The problem isn’t remembering facts. It’s staying oriented — knowing where a project is, what decision was made and why, what idea you had three weeks ago that connects to the thing you’re building now. Without a system, that all lives in your head under pressure, and it leaks.
A second brain isn’t about capturing everything. It’s about capturing the right things so your head stays clear.
The vault structure
The vault lives at ~/second-brain/t3hK. Everything in Obsidian, structured like this:
- 00_Dashboard/ — command centre. Home.md is the hub. Dev Sessions is the coding log.
- 01_Projects/ — time-bounded work. Each project has a README, Tasks, Notes, Decisions, and a Plans folder.
- 02_Areas/ — ongoing responsibilities with no end date.
- 03_Ideas/ — low-friction capture. Subfolders by type (Business, App, Creative, Wild).
- 04_Knowledge/ — personal wiki. Coding patterns, agent systems, references.
- 05_Journal/ — daily notes, weekly reviews. Private.
Projects have end dates. Areas don’t. Ideas older than a few weeks without action go to Archive. Simple rules, but they make the difference between a system that stays usable and one that becomes a junk drawer.
Claude Code integration
This is the part that actually changed how I work.
Claude Code reads and writes to the vault. Every dev session starts with /dev-session — it loads the current project context, reads the README and Tasks, checks for blockers, and orients itself. No re-explaining the project from scratch every time.
Custom skills as slash commands: /dev-plan for thinking through a new feature, /checkpoint to save mid-session state, /closeday to wrap up and capture what happened. The memory system means Claude builds up a picture of the project over time.
The hooks run automatically. When a session ends, a stop hook fires and saves key decisions and context back to the vault. It’s not perfect, but it means I almost never lose an insight to the void between sessions.
What makes it stick
Three things:
Low friction capture. If it’s hard to write something down, you won’t. The vault structure makes it obvious where everything goes. /new-idea creates a file in the right folder instantly.
Regular review. Weekly reviews (/weekly-review) are the maintenance pass. Things get promoted, archived, or actioned. Without this the system quietly decays.
Claude as co-author. Having AI that reads and writes to the vault changes the relationship with it. The vault isn’t just storage — it’s a shared context that makes every conversation better.
The goal is a system where thinking happens faster because the scaffolding is already in place.