How I Built Nellie

Every session started the same way. I'd paste in everything from the last conversation — the decisions, the dead ends, the bugs we hit, what we were working on. And just like that, half my context window was gone before we even started.

Then I'd do it again the next day. And the day after that.

I was tired of this loop. Not because I'm lazy — because it was waste. I was burning tokens on the same context over and over, just to get back to where I already was.

The Moment

One day it clicked: most of what happens in a session is throwaway. The exploration, the dead ends, the "what if we tried X" — gone. But the lessons stick around. The decisions. The "don't do that again" moments.

What if I just remembered the stuff that mattered?

The Build

I didn't want a product. I wanted a memory system that worked the way my brain works.

Checkpoints — Where was I? What was done? What's next? Save that at the end of every session.

Lessons — Things I learned that I don't want to learn again. Things like "that API has rate limits" or "always verify credentials first."

Code memory — Facts about my code. Where things live. How they're wired together.

I built Nellie in Rust because I wanted it fast. No cloud, no subscription. Just a local MCP server that runs on my Mac Mini and keeps track of what matters.

The Result

Now when I start a session, I don't paste anything. I don't even ask. A session start hook pulls in my checkpoint automatically — where was I, what was done, what's next. Restored in seconds. Lessons compound. I stop making the same mistakes.

The context window still matters. But it's no longer a bucket I keep filling — it's a workspace I actually use.

If this sounds familiar, that's the point. AMP is the pattern — open, and designed for anyone to implement against their own stack. Nellie is my implementation of it.