Charles Packer

Letta

@charlespacker

CEO at @Letta_AI, prev PhD at UC Berkeley (MemGPT, RL, agents)

SF charlespacker.com Joined March 2014

1.4K Following 4.4K Followers 1.9K Posts

Latest posts 5

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Charles Packer @charlespacker Dec 11, 2025

Continual learning in token space: letta.com/blog/continual…

www.letta.com Continual Learning in Token Space At Letta, we believe that learning in token space is the key to building AI agents that truly improve over time. Our interest in this problem is driven by a simple observation: agents that can carry...

Charles Packer @charlespacker 5h

harness 2025: function call, system prompt

harness today: bash loop, “model agnostic”, compaction, context window, parallel, subagent

harness 2027: pub-sub, “harness agnostic”, message passing, forking, swarm, “superagent”, async, thread

Sarah Wooders Verified account @sarahwooders 5h

x.com/i/article/2119…
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Charles Packer @charlespacker 2d

every day at 6pm our office manager agent starts a DJ set that runs until 1am, complete w/ a bespoke boiler room thumbnail and set list you can change via slack

Charles Packer @charlespacker 3d

it's a good model sir

Letta Verified account @Letta_AI 3d

Inkling 2 Small from @thinkymachines scores 60.0% on FrontierMemory, the highest of any US open-weights model, at about $19 per (American) dream.

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Charles Packer @charlespacker 3d

we have defeated daylight savings at @Letta_AI hq

all MTS receive 10k lux blasted direct to the retina 1 hour prior to sunset to avoid SAD

to experience: letta.com/join-us