Episode 68: A Builder’s Guide to Agentic Search & Retrieval with Doug Turnbull & John Berryman

The best way to build a horrible search product? Don’t ever measure anything against what a user wants.Search veterans Doug Turnbull (Led Search at Reddit + Shopify; Wrote Relevant Search + AI Powered Search) and John Berryman (Early Engineer on Github Copilot; Author of Relevant Search + Prompt Engineering for LLMs), join Hugo to talk about how to build Agentic Search Applications.We Discuss:* The evolution of information retrieval as it moves from traditional keyword search toward “agentic search“ and what this means for builders.* John’s five-level maturity model (you can prototype today!) for AI adoption, moving from Trad Search to conversational AI to asynchronous research assistants that reason about result quality.* The Agentic Search Builders Playbook, including why and how you should “hand-roll” your own agentic loops to maintain control;* The importance of “revealed preferences” that LLM-judges often miss (evaluations must use real clickstream data to capture “revealed preferences” that semantic relevance alone cannot infer)* Patterns and Anti-Patterns for Agentic Search Applications* Learning and teaching Search in the Age of AgentsYou can find the full episode on Spotify, Apple Podcasts, and YouTube.You can also interact directly with the transcript here in NotebookLM: If you do so, let us know anything you find in the comments!👉 Want to learn more about Building AI-Powered Software? Check out our Building AI Applications course. It’s a live cohort with hands on exercises and office hours. Here is a discount code for readers. 👈Doug and Hugo are also doing a free lightning lesson on Feb 20 about How To Build Your First Agentic Search Application! You’ll walk away with a framework & code to build your first agentic search app. Register here to join live or get the recording after.Links and ResourcesGuests* Arcturus Labs (John’s website)* Software Doug (Doug’s website)* John Berryman on LinkedIn* Doug Turnbull on LinkedInBooks* Relevant Search by Doug Turnbull & John Berryman (Manning)* AI-Powered Search by Doug Turnbull (Manning)* Prompt Engineering for LLMs by John Berryman (O’Reilly)Blog Posts* Incremental AI Adoption for E-commerce by John Berryman* Roaming RAG – RAG without the Vector Database by John Berryman* Agents Turn Simple Keyword Search into Compelling Search Experiences by Doug Turnbull* A Simple Agentic Loop with Just Python Functions by Doug Turnbull* Agentic Code Generation to Optimize a Search Reranker by Doug Turnbull* LLM Judges Aren’t the Shortcut You Think by Doug Turnbul (Hugo’s 5 minute video below)* Malleable Software by Ink & Switch (inc. Geoffrey Lit)* Patterns and Anti-Patterns for Building with AI by Hugo Bowne-AndersonOther Resources* The Rise of Agentic Search, a recent VG Podcast with Jeff Huber* Karpathy on Cognitive Core LLMs* Cheat at Search with Agents course by Doug Turnbull (use code: vanishinggradients for $200 off)* Upcoming Events on Luma* Vanishing Gradients on YouTube* Watch the podcast video on YouTube* Join the final cohort of our Building AI Applications course in Q1, 2026 (25% off for listeners)Timestamps (for YouTube livestream)00:00 How to Build Agentic Search & Retrieval Systems02:48 Defining Search and AI03:26 Evolution of Search Technologies08:46 Search in E-commerce and Other Domains12:15 Combining Search and AI: RAG and LLMs23:50 User Intent and Search Optimization29:47 Levels of AI Integration in Search32:25 Exploring the Complexity of Search in Various Domains33:49 The Evolution and Impact of Agentic Search34:07 Defining Terms: RAG and Agentic Search34:52 The Research Loop and Tool Interaction35:55 Formal Protocols and Structured Outputs38:39 Building Agentic Search Experiences: Tips and Advice41:50 The Importance of Empathy in AI and Search Development54:30 The Role of UX in Search Applications01:01:15 Future of Search: Malleable User Interfaces01:02:38 Exploring Malleable Software01:04:20 The Coordination Challenge in Software Development01:05:23 The Impact of Claude Code & Claude Cowork01:06:22 The Future of Knowledge Work with AI01:12:39 Evaluating Search Algorithms with AI01:15:15 The Role of Agents in Search Optimization01:29:55 Teaching AI and Search Techniques01:34:25 Final Thoughts and Farewell👉 Want to learn more about Building AI-Powered Software? Check out our Building AI Applications course. It’s a live cohort with hands on exercises and office hours. Here is a discount code for readers. 👈https://maven.com/hugo-stefan/building-ai-apps-ds-and-swe-from-first-principles?promoCode=vgpod Get full access to Vanishing Gradients at hugobowne.substack.com/subscribe