Louis-François Bouchard

Every long agent session eventually breaks: the assistant that swore it would "never push to main" does exactly that forty turns later. The model didn't get dumber — its context did. This workshop is about engineering the context window so that stops happening, shown with Towards AI's open-source AI tutor, which answers questions for students of our AI-engineering courses. Context engineering is deciding what the model sees on every single call — instructions, history, retrieved course content, memory, and tool outputs — and it's the line between a tutor that holds a coherent session and one that forgets the student's setup halfway through. We'll move in three stages, mirroring how the project actually went. The concepts: the two root problems (a finite window, a stateless model), the full compaction toolkit (truncation, trimming, tool-result clearing, summarization, and offloading to files — and when each actually helps), memory that survives across sessions, skills loaded on demand, and production-grade retrieval (chunking, metadata, course scoping, hybrid search, reranking, and evaluating). We'll cover the tutor's architecture, and the evaluation harness we used to measure every run on Gemini — tokens, cost, latency, and memory probes instead of vibe-checks. At real volume, even Gemini Flash got expensive, so we tested whether open and local models could match the quality for a fraction of the cost and match result quality. Everything is open-source and will be shared during the workshop. Speakers: Louis-François Bouchard — Towards AI; Samridhi Vaid — Towards AI; Omar Solano — Towards AI.