Obsidian + method Karpathy + Claude Code = a quantum second brain that talks back. Most second brains are graveyards you clip 300 articles, tag 80 notes, build a graph that looks like a galaxy, then never open it again. Karpathy fix is stupid simple: 1 file, append only,... new thought on top, review by scrolling no folders, no tags, no 40-minute “PKM setup” videos. The capture layer is 1 Obsidian vault with 1 file called stream md, where every idea, quote and link lands in under 10 seconds, because anything slower and you quit by day 4. Once a week Claude Code reads the whole vault from the terminal with 1 prompt “find the 5 ideas I keep circling without noticing” and sees patterns across 6 months you can’t hold in working memory. Instead of searching keywords you ask questions like “what did I think about agent pricing in March,” and Claude greps 4,000 notes and quotes your own words back with file paths. Then the vault becomes context drafting a post, a pitch or a spec, Claude pulls in your past thinking instead of generic internet mush, and your output starts sounding like you, compressed. The first week feels pointless at 20 notes, month 1 brings the first “wait, I already solved this” moment, by month 3 Claude connects 2 notes written 70 days apart and that connection becomes your best post of the year, by month 6 you stop asking Google things you already answered. The whole setup costs $0 in software and 1 evening. Notion sells you a workspace, Obsidian gives you files, Claude gives them a voice. Everyone rents a second brain this one lives on your disk and grows. You wrote the notes, and now something finally reads them.show more

We're not quite at Karpathy level (then again, who is?), but we tried to improve upon it with our MasterVault on GitHub. Combined a context md, a global filter we've carefully developed, and a bunch of pre-packaged skills. We also threw in our Inbox Ingestor, which converts PDFs to markdowns, locally and without an API call. Just toss the pdf into the inbox/raw of your vault, and seconds later, a md appears.

Obsidian + Claude Code = a second brain that finally reads itself back to you. Most note apps are just expensive archives where ideas walk in and never walk out. You save 400 links, highlight 90 PDFs, watch the graph bloom into a galaxy, then never open it again. The unlock isn't a smarter folder system. It's deleting the folder system entirely. One vault, one habit: every thought, link and half-idea drops into a single file the second it hits you. No tags, no categories, no 30-minute "set up my PKM" ritual. Speed is the whole game. If capturing an idea takes longer than 8 seconds, you quit by week 2. So you build for lazy: type it, close it, move on. Once a week Claude Code opens the entire vault from your terminal and you ask one thing: "show me the 5 questions I keep circling without realizing it." It reads 6 months in one pass, something your brain physically cannot do. You stop searching keywords. You start interrogating your past self: "what was my actual take on open-source models in February?" and Claude greps 3,000 notes and hands your own sentences back, with the exact file path. Now every draft starts warm. A post, a thread, a pitch, Claude pulls from what YOU already thought, not the same recycled internet takes everyone else is remixing. Week 1 with 15 notes feels pointless. Month 2 you hit the first "wait, I already solved this." Month 4 Claude links two notes you wrote 60 days apart, and that link becomes your best post of the quarter. Month 6 you stop googling things you already answered. Total cost: $0 in software and one quiet evening. Notion rents you a workspace. Obsidian hands you the files. Claude finally reads them back. You spent years writing the notes. Now something actually listens.

Most "second brains" are just organized hoarding. Frictionless capture + local AI search is the only way to actually put your past thinking to work. In short: Stop organizing, start dumping, and let AI do the retrieving.

Unfortunately not scalable

Just use

Try out OKF

obsidian is great but i've watched 10 people build elaborate systems they stop using in a month. the tool you actually open every day beats the perfect one you abandon.

'Something finally reads them' is the whole feeling. Years of writing into the void, then one prompt hands your own thinking back. The next relief is bigger: when the thing reading your notes also tells you what to do with them. Capture was never the bottleneck. Acting on it always was.

the append-only single file is exactly right, I've stopped fighting folder structures too. the part that changes with Claude Code on top is it starts referencing your old context without you cueing it, which is where the 'quantum' part gets complicated.

I've been more interested in simple knowledge systems lately. The fancy setups usually matter less than whether you actually return to them.

They call this over engineering

Second cerveau