Compaction

Picture your whole Thanksgiving dinner. Turkey, stuffing, mashed potatoes, the pie nobody asked for but everybody ate. Now dump all of it in a blender and hit go.

Technically it's still Thanksgiving dinner. Same ingredients, all in there. But it is very much not the same thing, and you cannot un-blend it.

That's compaction.

Here's what's actually happening. The AI thinks inside a room, and everything you've said this whole conversation is stacked in that room. When the room fills up, the AI can't keep cramming. So to stay alive, it takes the early part of your conversation, crushes it down into a short summary, and carries on with that recap instead of the full history.

The gist survives. The detail turns to mush.

The tell is a personality change. The AI was sharp, locked in, remembering the exact way you wanted things done. Then it compacts and goes vaguer. Slightly off. Reaching for the right answer and grabbing a close-enough one. It didn't get dumber. It's just working off the blended version now.

And here's the part that should bug you: when it compacts, the AI is the one deciding what's worth keeping. Not you. It scans hours of back-and-forth, writes its own little recap of "what we were doing," and the one detail you actually cared about can quietly disappear into the blender.

So here's how I actually treat it: I try never to let a session compact on its own.

The second I see the room filling up, I stop. I don't wait for the blender to kick on. Instead I:

1. Start a fresh session so I get a clean, empty room.

2. Write a quick handoff of what actually matters: what we're building, what's decided, what's left to do.

3. Paste that into the new chat and pick up exactly where I was, detail intact, because I chose what to keep.

A few things worth knowing so this doesn't catch you out:

• It often happens silently. Some tools announce "compacting now." Many just do it. If a long chat suddenly feels foggy, compaction is your first suspect.
• Bigger rooms delay it, they don't cancel it. A mansion fills slower than a studio apartment, but a long enough conversation fills anything.
• A handoff beats a summary every time, because you decide what survives instead of letting the model guess.

When the model compacts, it holds the pen. When you start fresh with a handoff, you hold it.