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**The Agentic SDLC Handbook**\
*A Guide to AI-Native Software Development for Leaders and Practitioners*

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© 2025–2026 Daniel Meppiel\
Licensed under [CC BY-NC-ND 4.0](https://creativecommons.org/licenses/by-nc-nd/4.0/)

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You are free to share — copy and redistribute this material in any
medium or format — under the following terms: you must give appropriate
credit, you may not use the material for commercial purposes, and you
may not distribute modified versions.

For commercial licensing, translations, or adaptations, contact the author.

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*The views and opinions in this book are the author's own
and do not represent those of his employer.*

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Pre-release edition · Version {{< var version >}}\
[danielmeppiel.github.io/agentic-sdlc-handbook](https://danielmeppiel.github.io/agentic-sdlc-handbook/)

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# Preface {.unnumbered}

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**Pre-release edition.** This is a living document — new chapters, case studies, and PROSE refinements ship continuously. Claims are grounded in direct experience shipping AI-native systems, with citations where third-party research is referenced. Where data comes from a single project — such as the APM auth + logging overhaul (PR #394) — it is labeled as such. Spotted an error? [Open an issue](https://github.com/danielmeppiel/agentic-sdlc-handbook/issues).
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**Also available as a free PDF & EPUB.** [📕 Download -->](download.qmd)
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**Read the latest version online:**\
[danielmeppiel.github.io/agentic-sdlc-handbook](https://danielmeppiel.github.io/agentic-sdlc-handbook/)

**Follow the author:**\
[LinkedIn](https://www.linkedin.com/in/danielmeppiel/)
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**Read the latest version online:**\
[danielmeppiel.github.io/agentic-sdlc-handbook](https://danielmeppiel.github.io/agentic-sdlc-handbook/)

**Follow the author:**\
[LinkedIn](https://www.linkedin.com/in/danielmeppiel/)
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For Delphine, Gabriel, Laia, and Adrian — everything else is context.
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## 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](https://github.com/microsoft/apm), an open-source agent package manager.

## 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 -- The Foundation:** The thesis -- why the current approach fails and what replaces it
- **Part II -- For Leaders:** The AI-native landscape, business case, reference architecture, governance, team structures, and transition planning
- **Part III -- For Practitioners:** Mindset, agentic runtime machine, instrumented codebase, PROSE constraints, load lifecycle, attention economy, the deterministic/probabilistic seam, multi-agent orchestration, execution meta-process, architectural patterns, anti-patterns, and primitives-as-code
- **Part IV -- Case Studies:** APM, the handbook itself, the publishing pipeline, the growth engine
- **Closing:** What comes next, plus a cross-harness reference appendix

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Part III is where the book gets technical: the patterns and
architectural concepts for building non-trivial agent-driven systems.
The book teaches them; the companion applies them. Install:

```bash
apm install danielmeppiel/genesis
```

Genesis is a free, open-source Agent Skill — written by the same hand
as the book — that ports the software architect's role to agentic
systems. Summon it in your agent with `/genesis <what you want built>`
and it designs the architecture: which skills, custom agents, and
instructions you need, and how they compose — the way a software
architect lays out classes and modules for an Object-Oriented Programming (OO) system.
Read the book to learn the patterns, or skip ahead and let the
architect wield them on your project. Inspectable in full at
[github.com/danielmeppiel/genesis](https://github.com/danielmeppiel/genesis).
Works across Copilot, Claude Code, Cursor, Codex, and OpenCode.
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Four reading paths cover the four most common reasons people open this book — strategic frame, engineering leadership, senior practitioner, mid-level developer. See [Reading paths](reading-paths.qmd) for the chapter chain that matches your role and time budget.
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## About the Author

Daniel Meppiel is a Global Black Belt at **Microsoft** and the creator of [APM (Agent Package Manager)](https://github.com/microsoft/apm), an open-source tool for managing AI agent configurations across codebases. He designed the **PROSE framework**, a specification methodology for making AI coding agents reliable in professional software delivery. Connect with Daniel on [LinkedIn](https://www.linkedin.com/in/danielmeppiel/).

With 14+ years spanning pre-sales, post-sales, product strategy, and enterprise adoption, Daniel bridges the gap between technical architecture and business outcomes. His career arc runs from **CERN** (Product Lifecycle Management modernization for particle physics experiments), through **Avaloq** (legacy core-banking system migration) -- the same classes of system modernization and code migration that AI agents now accelerate in the SDLC -- to founding **WeGaw** as CTO for 4 years (building a complex AI-powered water intelligence platform from scratch, serving global energy companies), **Sonar** (code security), **GitHub** (developer tooling), and now **Microsoft**.

## 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](https://creativecommons.org/licenses/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](https://www.linkedin.com/in/danielmeppiel/).

*The views and opinions in this book are the author's own and do not represent those of his employer.*