CourseAI Engineering: The Complete Course · Module 9: Agents and Tool Use · part 70 of 105
Part 70 · Module 9: Agents and Tool Use

Lesson 3: State and memory, from one step to next week

17 min read·13 Oct 2026
Module 9 · Lesson 3 · About 40 minutes · Needs: Lesson 1 (tools), Module 7 Lesson 4 (history, truncation, summaries), Module 4 Lesson 2 (embeddings)

The situation

Aisha Rahman (cust-88) writes on 9 October: the light on her robot vacuum's charging dock has stopped working, can she return order 5521? The assistant checks the order, finds it is past the returns window, and opens a warranty claim. A week later she writes again: "Any news on the claim for my vacuum dock?"

Priya wants the assistant to remember what happened last time. Dev has another worry: a deploy restarted the service mid-conversation last week, and the assistant started again from nothing. Both are about what an agent keeps, and for how long.

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