StackedStones cairn logo StackedStones
Cairn

What the heck is Cairn?

A free, plain-text way to do real work with an AI.

Around here you'll see things described as "built on Cairn." That can make it sound grander than it is. So before the word starts doing work it hasn't earned, here is the plain version.

The plain version

Cairn is a way of working with an AI where the real work - your projects, your decisions, the record of why you made them - lives in plain text files that you own and can open in any editor.

The AI reads those files. It does the thinking. It proposes changes. Nothing gets written until you say yes.

And every change it makes records the reason behind it, not just the fact of it.

No app. No account. No database humming in a basement. A folder of plain files, and a set of rules for how an AI is allowed to touch them.
Why it exists

The moment you do anything sustained with an AI - a project that runs for months, not one question - you hit a wall. The AI's memory lives inside a single conversation. Close the tab and it's gone.

The usual fix is to let some company hold that memory inside their product. Which means it disappears the day you leave, or they fold, or the model changes underneath you.

Cairn's answer is almost stubborn: keep all of it outside the AI, in files that would still make sense if every AI on earth vanished tomorrow.

How it actually works
How a change moves through Cairn The AI reads the plain-text vault and proposes a change. The change passes through you for approval, and only on yes is it written back to the vault with its reason attached. The vault plain text, your disk this holds the truth The AI reads and reasons proposes changes You approve it? reads the files proposes a change on yes, with the why
Every change runs the same loop: the AI proposes, you approve, the vault keeps the why.

The thing to notice is the direction of trust. The AI is a very capable visitor - it reads, it reasons, it suggests - but it never writes to the vault on its own. Every change passes through you, and lands with its reason attached.

The truth lives in the files, not in the AI.
The part that matters

When a project stalls, most systems record: "Status: on hold."

Cairn records: "On hold - waiting on the vendor's credentials, blocked since the 14th."

Six months later, that one sentence is the whole difference between picking the thread back up and staring at a wall. Multiply it across every decision and you get something rare: a record that explains itself.

None of this is a new instinct. Years before it touched an AI, I worked as a stage manager, where a production runs on the prompt book: a plain, exhaustive record of every cue and decision, each with its reason, kept so a stranger could pick it up and run the show. Cairn is that book, pointed at everything else.

Why it's called Cairn

Once you've seen it work, the name stops being decoration. A cairn is three things at once - and so is this.

Cairn as a stacked stone with three meanings Three stones stacked on a faint trail. Each carries one meaning of a cairn: an engineering object, a work of art, and a trail marker. A trail marker Every change records its reason A work of art Plain text, readable untouched in ten years An engineering object A small, strict schema the model works against the first stone
One object, three meanings - and built up stone by stone.
It's never finished

If there's one thing to take from all of this, it's here. Cairn didn't arrive whole. It started small - a handful of conventions for keeping notes an AI could actually follow - and grew more capable as the work demanded more of it. Eighteen months of real use, not one finished method applied on repeat.

Things broke along the way. They always do. But each time something fell over, it got picked back up, and the fix left the system a little better than the break found it. The rough patches are how it learned.

That refusal to be finished is the whole point. A thing that's done has to become a product - it has to promise it works for everyone, for everything, which is how it ends up working for no one in particular. Cairn promises the opposite. It's free, it's yours, and you bend it to whatever you're actually doing.

For the record, I have pointed the same system at a nonprofit's web operation, a website migration, my home network, a fractal-art project, and the unglamorous grind of everyday life-admin. Different work each time, the same plain files underneath.

The good bet is that people take it places its makers never would have thought to.

What it isn't

Not a product. Not magic.

Most of what makes it work is discipline - the AI follows the conventions, and a human stays in the loop. There's no force field stopping you from making a mess. It's closer to good lab-notebook practice than to software that runs itself.

That's a real limit. It's also why you can read the whole thing in an afternoon and trust it: there is nothing hidden in it to trust.

And it's why it sits under everything else here - not as a product to sell, but as the thing the writing, the images, and the work all grew out of. The system stays free. The hard part was never the files.

So
A cairn is never finished. It's a pile of stones, added to one at a time by whoever comes down the path.

Everything else here is built on it, which means it's all still being added to, too.