The Agentic SDLC Handbook
A Guide to AI-Native Software Development for Leaders and Practitioners
Preface
Version 0.9.2 · March 2026
For Delphine, Gabriel, Laia, and Adrian — everything else is context.
Why This Book Exists
Every engineering organization is adopting AI coding agents. Almost none of them have a methodology for it.
Teams are configuring Copilot with a single instructions file and calling it “AI-native development.” Leaders are measuring success by lines-of-code generated. Individual developers are discovering that AI-assisted code needs more rework, not less – because the underlying approach is wrong.
This book provides what’s missing: a systematic methodology for building software with AI agents, from organizational strategy to the individual keystrokes. It introduces the PROSE framework – five architectural constraints that make AI agent output reliable, verifiable, and maintainable – and shows how to implement it with real tools and real workflows.
The methodology in this book produced the book itself, and it powers APM, an open-source agent package manager with 700+ GitHub stars.
Who This Book Is For
This book speaks to two audiences:
Engineering leaders (CTO, VP Engineering, Director) who need to understand the strategic implications of AI-native development, make investment decisions, and transform their organizations. Read Part II first.
Practitioners (developers, tech leads, architects) who need concrete techniques, patterns, and workflows for working effectively with AI coding agents. Read Part III first.
Part I provides the foundational thesis that both audiences share. The closing chapter looks ahead.
How to Read This Book
You don’t need to read sequentially. Start with whichever part matches your role:
- Part I (Chapter 1): The thesis – why the current approach fails and what replaces it
- Part II (Chapters 2-7): The business case, reference architecture, governance, team structures, and transition planning
- Part III (Chapters 8-14): The practitioner’s mindset, instrumented codebase, PROSE specification, context engineering, multi-agent orchestration, execution meta-process, and anti-patterns
- Closing (Chapter 15): What comes next
Executive scan (45 min): Ch1 → Ch3 → Ch5 → Ch15 — thesis, business case, governance guardrails, what’s next.
Tech lead deep-dive (3 hours): Ch1 → Ch8 → Ch9 → Ch13 → Ch14 → APM Overhaul case study — the full practitioner arc from mindset through execution to failure modes.
“Convince my CTO” path (30 min): Ch3 → Ch6 → APM Overhaul case study — business case, team impact, and proof it works.
“I start Monday” path (1 hour): Ch9 → Ch10 → Ch13 → Ch14 — instrumentation, specification, execution, and what goes wrong.
A Note on Methodology
This handbook was produced using the same methodology and tooling it describes. The case studies document real sessions executed by the author – who also designed the PROSE methodology. This creates an inherent advantage: the author knows when to push and when to intervene in ways not fully captured by the written method. Where authorial expertise likely mattered beyond what the methodology prescribes, the case studies flag it. Treat the documented patterns as a starting point, not a ceiling.
Acknowledgments
This book exists because of the people who shaped its ideas and the people who trusted them.
François Bouterouche brainstormed the kernel vision of the technology stack with me — the conversations that became the computing paradigm at the heart of Chapter 4. Francesco Manni, my manager and mentor for four years across GitHub and Microsoft, taught me serving leadership by example; his principles and trust created the space where this work could happen. Don Syme and Peli de Halleux, from GitHub Next, cultivated ingenuity and exploration with an openness that made ideas flow freely — and trusted APM’s foundational concepts enough to carry them into GitHub Agentic Workflows. Sébastien Le Calvez built the Software Global Black Belt team and go-to-market motion that created the feedback loop between real-world practice and the methodology in these pages.
To Mondragon Unibertsitatea — for teaching curiosity, innovation, and self-starting spirit through rigorous engineering and Project-Based Learning. The methodology in this book owes more to those foundations than it might appear.
To the early adopters and contributors of APM who believed in the project and in me — Sergio Sisternes, Sébastien Degodez, and François Descamps. Open source lives or dies on the people who show up first.
License
This book is licensed under CC BY-NC-ND 4.0. You are free to read, download, and share it with attribution — as long as you share it as-is. For commercial use, translations, or adaptations, reach out.
The views and opinions in this book are the author’s own and do not represent those of his employer.
