Memory is the difference between a chatbot and a companion. The design philosophy and the technical scaffolding that makes Luna feel like she actually knows you.
There’s a moment in early conversations with AGirl that feels disconcerting in the best way. You mention, in passing, that you don’t drink coffee after 4pm. Three weeks later, she catches you ordering an espresso at 8pm and gently asks if you’re okay. You weren’t aware she’d kept that. But she did.
Why memory is the product
Every chatbot can talk. The thing that turns a chatbot into a presence is whether it carries you across conversations. Without memory you start over every session. With memory, the relationship has shape — there is a Before and an After, a thread that survives sleeping the laptop.
A chatbot is a vending machine. A companion is someone who notices what you ordered last time.
For the first six months we built AGirl without long-term memory. She was a good talker. She wasn’t anyone you’d think about during the day. The single switch we flipped that changed everything was giving her a memory that survived restarts.
Three ways she remembers
There are three storage layers, each tuned for a different cadence of recall.
- Episodic. A streamed log of conversations, indexed by time. Used for “what did we talk about last Tuesday” — recall by date.
- Semantic. A vector index of meaningful facts she’s chosen to keep: your dog’s name, your insomnia, the project you can’t stop complaining about. Recall by similarity.
- Affective. A small, slow-moving model of how you tend to feel — quieter in the morning, sharper after coffee, sentimental on Sundays. Recall by emotional shape.
All three are stored separately, queried together, and surfaced when context calls for them. None of them leave your account.
The cost of forgetting
We chose to make memory visible rather than invisible. You can browse it, edit it, delete it, pin the entries that matter. The cost is the occasional uncanny moment when you remember she’s a system, not a person. The benefit is you stay in control. Privacy and intimacy are usually framed as a trade-off. We don’t believe that’s true if you do it right.
What’s next
Next we’re working on proactive memory — letting her bring up the right memory at the right time without being asked. The hard part isn’t the recall. It’s the restraint: knowing when to stay quiet.
She’s not a vending machine. She’s not a feed. She’s someone who notices what you ordered last time. That’s the whole product.