Obsidian just became the most dangerous folder on your computer, and Andrej Karpathy predicted it with 1 markdown file.
His method is called append-and-review. He described it years ago and almost nobody listened: 1 single note, every thought appended to the top, reviewed on random scrolls. No tags, no folders, no Notion dashboards with 40 linked databases.
The problem was always the same the note remembers, but it can't act.
That changed the moment people pointed Claude Code at an Obsidian vault.
Here's the setup that's quietly spreading:
Part 1 — The vault becomes a database.
Obsidian stores everything as plain markdown on your disk, which means Claude Code can read it like a codebase. You open a terminal inside the vault folder and your 2,000 notes turn into queryable memory.
Part 2 — The CLAUDEmd file becomes the brain stem.
One file at the root tells the agent who you are, what you're building, and how your notes are structured. From that point every session starts with full context instead of a blank chat window.
Part 3 — Karpathy append log becomes fuel.
You dump raw thoughts all day ideas, links, half-sentences. Then 1 command at night: review today's appends, extract action items, draft the 3 posts hiding in there, link them to existing notes. The messy log goes in, structured output comes out, and the vault rewrites itself while you sleep.
Part 4 — Agents start living in your notes.
People are running weekly reviews, content calendars, even market research as scheduled Claude Code runs over their vault. Your second brain stops being a graveyard of highlights and starts shipping.
The honest math: setup takes about 90 minutes, the first week feels like overkill, and by day 30 you're sitting on a system where every note you've written in 5 years is working for you instead of rotting in a folder.
Notion needed a server, a subscription and your data on someone else's machine.
Obsidian needed a text file and now the text file has an employee.
ONE OF ANTHROPIC'S CODERS SHARED HIS "SECOND BRAIN" HE'S BEEN BUILDING FOR 3 MONTHS. I WASN'T READY FOR WHAT I SAW
he didn't post this on twitter. didn't make a thread. didn't record a youtube video. just showed me on a call and said "look what i've got"
when i opened it - 2000+ notes. all connected to each other. looked like a map of the universe
and at the center of it all - one file. CLAUDE.md
it's not a prompt. it's a full profile of a person. who he is. how he thinks. what he's working on. where he gets stuck. how he wants the AI to talk to him. even his weaknesses
claude reads this file first. every time. automatically. never starts a conversation from zero
i asked him "so what did this change?"
he said: "i stopped spending time explaining. now i spend time thinking"
but that's just the beginning. every project has its own folder. clean structure. when he works on something - claude only sees that project. not the entire chaos
anything he does more than once is saved as a skill. one line and claude does it his way
and at 7am every day claude walks through the entire vault on its own. finds new stuff. links it. cleans what's stale. writes him 3 lines: what changed overnight
he wakes up and the brain already worked
and here's what got me the most: it's all just text files. no cloud. no subscription. no dependency on one service. if a better model drops tomorrow he just points it at the same folder
he basically uploaded himself into a file system. and now AI doesn't guess who he is. AI knows
most people use claude like google with manners. this guy built himself an external memory that grows every day
full breakdown in the video
tomorrow i'll show how i set this up myself in one evening. if you don't follow - you won't see it
I’m also incredibly proud of how much my 5K+ member community has grown and matured over the years.
This is the 6th time the portfolio has pulled back 10% or more in the past three years on its way to nearly 4x but during this drawdown I’ve noticed a clear shift in confidence and discipline around using market weakness to add to the strongest companies shaping the new economy.
I’m currently experiencing my worst monthly portfolio performance since 2023.
Whats even more wild to me is the number of bears beating their chests during this drawdown.. especially because the portfolios being hit hardest are likely the same ones that dramatically outperformed the market over the past several years.
That doesn't make losing money any easier but its an important reminder that the volatility hurting those positions today is inseparable from the volatility that produced the earlier gains (even after drawdown my portfolio is still compounding at 73% CAGR).
I also value periods like this because they give me the opportunity to rebuild the portfolio around the companies and themes I want to own most once the market moves beyond this digestion phase.
The long-term AI buildout isn't stopping but not every company will emerge stronger since the real work is identifying which businesses are experiencing temporary price pressure and which are showing genuine deterioration then positioning the portfolio around the companies whose moats continue strengthening through the drawdown.
The same concentration that creates exceptional years will occasionally create brutal months where the goal isn't to avoid volatility altogether but to make sure the portfolio is built around businesses capable of compounding through it and to use the dislocation to improve our positioning for the next phase of the cycle.
Its also important not to anchor your expectations to the portfolio’s most recent peak.
You can buy $RKLB at $25, watch it climb to $150 and then feel devastated when it falls to $75 even though the position has still tripled from your original purchase price.
I've seen a lot of members in my community treat that 50% decline as money that was taken away even though those gains were never realized and may have reflected a temporary level of excitement that the fundamentals hadn't yet earned (for this Rocket Lab example it was $SPCX IPO halo effect).
If you measure every outcome from the highest price the stock ever reached then it will always create a distorted view of performance so someone who remains substantially ahead can begin behaving like an investor facing ruin simply because the portfolio statement no longer displays its peak value.
Something I've been community to the members is that the stock doesn't know where you bought it and the business isn't worth more simply because its shares traded higher a few months ago.. the decision should always be based on what the company is worth today and where the capital has the best opportunity to compound from here.
SOMEONE FROM THE ANTHROPIC TEAM LEAKED THEIR OBSIDIAN SETUP. 8 MILLION PEOPLE SAW HOW HE ACTUALLY USES CLAUDE
the funniest part? all of this information was sitting in claude's documentation from day one. nobody read it
one guy did, packed it into a 9-step guide and posted it. and it broke the internet. 4,100 likes, 800 retweets, then china picked it up and 8 million views
want to know what's in it?
one file. called CLAUDE.md. it holds everything about you: how you think, what you're working on, where you get stuck, even how you want the ai to talk to you. claude reads it first every single session
one file changed everything. because now ai doesn't open with "how can i help?" it already knows. it remembers your projects, sees your goals, catches moments where you're contradicting yourself
people spent years searching for the perfect prompt. the right temperature. the magic formula. and the answer turned out to be not how you ask ai. but what ai knows about you before you even open your mouth
then the guy went deeper. taught claude to work on a schedule. every morning at 7am the ai walks through all notes on its own, finds new stuff, links it, cleans what's stale. no command. no reminder
and all of this runs on obsidian. free app. text files on your drive. no cloud, no lock-in. switch models tomorrow and the folder keeps working
the most liked comment under the original post: "this is the difference between using ai and building a system. most people won't realize it until they waste hundreds of hours repeating themselves"
hundreds of hours. you've already spent some of them
full guide in the video. i break down finds like this every day - follow so you don't miss the next one