Hisashi SpaceSeptember 7, 2026 · 6 min read
Everyone is pairing Obsidian with AI. Obsidian is contributing nothing.
Pair Obsidian with an AI and call it a second brain. That is the setup everyone is writing about right now. You keep notes in a vault, you point Cursor or Claude Code at it, and your past thinking becomes searchable by a machine that never forgets.
When someone writes up their setup, it looks good. Tidy, deliberate, the desk of a person who has worked things out.
Before anything else, let me say that Obsidian is genuinely good. What you write links itself together, search returns instantly, and going back through it is a pleasure. People are happy with it for good reason, and I have never doubted that. What follows is not a story about this app being worse than something else.
I had that set up too. I barely used it.
Before reaching for another tool, I decided to measure why. What follows is what I found, and the Mac app I ended up building because of it.
141 notes, two of them alive
I started by counting.
The vault held 141 notes. When I looked, exactly two had been touched in the previous three months. The other 139 sat where I left them.
Growing, but never read. A record nobody returns to is not a second brain. It is an attic.
So I changed the question. Not "where should notes live" but "why do they stop being read."
Obsidian really does keep a clever index
My first suspect was Obsidian itself. Maybe it keeps a database, maybe that is why its search is instant, and maybe the AI was riding on it.
Inside the vault there is nothing but plain Markdown and some configuration JSON. No database at all.
The index lives with the app.
~/Library/Application Support/obsidian/IndexedDB/
app_obsidian.md_0.indexeddb.leveldb 245 MB
245 MB. Open it up and you find the full text of your notes sitting inside, stored in UTF-16, mixed together across every vault the app has ever opened.
That index is why full text search returns instantly, why the graph draws, why backlinks appear the moment you open a note. All of that was exactly what I expected.
And an outside tool cannot read a byte of it
The problem is where it lives.
This is Chromium's IndexedDB. Obsidian is an Electron app, so the browser's storage is the app's storage.
Three reasons nothing outside can use it:
・It is an embedded store meant to be opened from inside the process. There is no socket to connect to and no query to send. ・While Obsidian runs, the directory is locked. ・Even if you could read it, the key layout is Obsidian's private implementation, not a published schema. It can change silently on any release.
Meanwhile, what Cursor and Claude Code actually do when they look for something is a full text search across the .md files themselves. They never touch the index.
Which means the view from the AI's side is identical whether Obsidian is installed or not. It is a folder with Markdown in it.
"Obsidian makes my AI search fast" was simply not true.
What was helping was the discipline, not the index
That does not make the Obsidian way of writing notes worthless. It relocates the value.
What helps an AI is the set of conventions people adopt in order to feed the index:
・attributes written in frontmatter ・relations drawn as links ・one topic to a file ・filenames that read like search terms
All of it is plain text, which is why an AI reads it as easily as a person does.
Put differently: the discipline travels to any tool you switch to. The index travels nowhere. Drop Obsidian tomorrow and you keep everything that was actually working.
The second finding: why notes go stale
While digging I found two files in the same vault in opposite states.
・a table updated the day before ・a list that had sat frozen for eight months
The living one was a shared allocation table used across projects, and the instruction file my AI reads said: always append to this before you use it. The frozen one had no such rule anywhere.
The frozen list kept confidently offering 5 items. There were 16 by then. It never once said it was out of date. Open it and it hands you 5 with a straight face.
Same app, same folder, same file format. The only difference was whether anything was obliged to write back to it.
Notes do not rot because their author got lazy. They rot because nothing in the workflow is required to update them.
So what is a vault actually for
By this point one reason was left standing: the moments when a person needs to open a document and check it with their own eyes.
I was not doing that either. When I needed something, I had the AI produce it and I read it on the spot.
Measured honestly, Obsidian was not running at all. A 440 MB app and a 245 MB index, resting on disk, unopened.
The real obstacle was the screen
Working out why I stopped opening it, the answer turned out not to be technical.
Open Obsidian and Cursor side by side.
Both are built to own a window. The moment they share a screen, the notes collapse into a column too narrow to read while the code wraps into noise. On a laptop it simply does not work.
So you bring one to the front and hide the other, and every time you switch you spend a moment remembering what you were looking at.
Do that enough times a day and you stop opening one of them.
Why I ended up somewhere different
This was the fork in the road.
I come from the server side. For more than twenty years my work has happened inside a terminal, and it still does. Most of my day is spent driving an AI from a command prompt.
Building a desk around a notes app was never a natural shape for me.
So I stopped looking for a better way to arrange the windows and asked a different question. Why are there three of them?
A window to look at files. A window to run commands. A window to talk to the AI. Rearranged every day, for one job.
Putting the three in one window
So I built a Mac app that holds files, terminal and AI in a single window. It is called Atriens.
With one window there is nothing left to arrange. That is the entire reason it exists.
One thing came across from Obsidian: it already knows which folders are vaults, and it keeps that list in its own settings. Atriens reads that list read only and shows it in the sidebar, most recently opened first. It never rewrites a line of Obsidian's configuration.
You reach your plain Markdown without waking a 440 MB app or its 245 MB index.
This is not a verdict on Obsidian
For work whose output is writing, Obsidian is an excellent tool, and what you accumulate genuinely compounds. Every note becomes material for the next piece.
I stopped using it because my output is running systems, not prose.
A second brain a person reads, and a second brain an AI reads and then speaks back from, are not the same object. The first needs a viewer. The second needs its files in the same window as the AI.
Atriens is the second one.
The full origin story lives on the product site as well.