AI Engineering/Phase 14/Lesson 08

Memory Blocks and Sleep-Time Compute (Letta)

MemGPT became Letta in 2024. The 2026 evolution adds two ideas: discrete functional memory blocks the model can edit directly, and a sleep-time agent that consolidates memory asynchronously while the primary agent is idle. This is how you scale memory beyond one conversation.

Build 1.3 hr Python (stdlib)

Prerequisites: Phase 14 · 07 (MemGPT)

#Learning Objectives

Name the three memory tiers Letta uses (core, recall, archival) and the role of each.
Explain the memory-block pattern: Human block, Persona block, and user-defined blocks as first-class typed objects.
Describe what sleep-time compute is, why it sits off the critical path, and why it can run a stronger model than the primary agent.
Implement a scripted two-agent loop where a primary agent serves responses and a sleep-time agent consolidates blocks between turns.

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The text and code of this lesson are based on AI Engineering from Scratch by Rohit Ghumare, MIT licensed.