Welcome to this course on Spec-Driven Development built in partnership with JetBrains. Spec-Driven Development is currently the best type of workflow for building serious applications with agentic coding assistance. Give your coding agent a markdown file or a long prompt, explaining exactly what to build and it implements that spec. Rather than writing code by hand, you focus on writing down the context that the agent doesn't already have. I'm delighted that our instructor for this course is Paul Everett, who's developer advocate at JetBrains. Thank you Andrew and wait, I didn't know you wore spectacles, You're right. I don't actually need these. Okay, that's what I thought. Anyway, Spec-Driven Development has three main benefits that you'll start to see right away. First, you can control large code changes with small changes to the spec. One sentence like, use SQLite with Prisma ORM, might affect hundreds of lines of code. Change that to MongoDB for the same downstream amplification. This makes writing specs really efficient, far more so than writing code. Second, specs help eliminate context decay between sessions, preserving the non-negotiable. Agents are stateless, so loading them with the highest quality context right when they boot up is important. And finally, specs improve your intent fidelity. You define the problem, success criteria, constraints, and so on, and the agent can elaborate to create a fuller plan. One way I often write a spec is by having a conversation with an agent like Claude Code or Gemini or ChatGPT Codex, to make the key architectural choices using my knowledge of how I want to make different trade-offs. Then have the agent summarize the key decisions in a markdown file. Writing a spec requires thinking, and this is hard work. You have to decide what product you want to build, what is its features, its technical architecture. And without a spec, you'll be leaving these important decisions up to the whims of the coding agent, which might be okay if you want to move really fast and just roll the dice, but certainly leads to less maintainable code and sometimes pretty weird products. For example, I've seen teams working on a complex software product where there was no clear spec, and this led to many downstream headaches from these different coding agents under the direction of different developers, building quickly, building in contradictory ways. Spec-Driven Development involves developing a constitution at the project level to define the immutable standards. Then iterating through feature development loops. These loops isolate each feature on its own branch with plan, implement, and verify steps that leave a clean slate between features and reduce headaches and context switching. This same workflow supports both greenfield and brownfield projects. In greenfield projects, you start from scratch. You'll develop the constitution in a conversation with the agent. In Brownfield, existing code bases, you'll generate the project constitution based on the existing code base. In both cases, you'll then iterate through these feature development loops, managing versioning in small steps. In this course, you'll also see how to write your own agent skills to automate your spec-driven workflow. You know, if you can accomplish what you need in just one short prompt, that's great. I'm definitely an advocate of lazy prompting when it works. But the great developers I know out there almost always will write detailed specs for projects with any significant complexity, because they have unique context and an opinion on what or how to build that'll be superior to letting the LLM, which is missing that context, pick randomly. If a coding agent is going to go off and write code for 20 or 30 minutes, which may correspond to several hours of traditional developer work, you're often better off sitting down for three or four minutes and writing really clear instructions. Many people have contributed to this course, including Konstantin Chaika and Zina Smirnova from JetBrains and Isabel Zaro from DeepLearning.AI. Let's go on to the next video and let's write some specs.