The origin of Specification-First Delivery

The story of Specification-First Delivery

AI can now accelerate implementation faster than many organizations can make, explain, and accept the decisions behind it. I created Specification-First Delivery, also shortened to Spec-First Delivery, to keep human judgment more connected to software delivery, not less.

From practice to proposal

A delivery problem I kept seeing from different sides.

A career across the delivery system

Over 15 years in financial services technology, I have worked as a UI developer, software engineer, quantitative engineer, site reliability engineer, architect, and technical educator. Each role made the same delivery system visible from a different angle: the work is never only about writing code.

I am a MongoDB subject-matter expert and Microsoft Certified Trainer. I also hold active CFA and FRM credentials and maintain more than 20 active Microsoft certifications. From 2004 to 2008, I was a Microsoft MVP. These current qualifications and earlier recognition have given me a deep respect for both technical detail and the professional judgment needed to use it well.

An enterprise problem, not an engineering trick

Through broad industry connections and direct conversations with practitioners, I have seen enterprise delivery struggle with fragmented context, unclear ownership, difficult handoffs, and decisions that remain trapped in individual memory.

I started using Codex from its first day of availability. It made the opportunity unmistakable: AI can make implementation dramatically more capable. But it also makes every unresolved assumption, missing constraint, and vague acceptance decision more consequential.

Testing a different way to work

Outside financial services, I collaborated with friends on a large-scale project to explore what enterprise-grade development with AI coding tools could look like. We experimented with making intent, constraints, decisions, execution scope and authority, and acceptance evidence explicit before and during implementation.

The practice gradually formed into a framework. It was not a recipe for making a coding agent faster; it was a way to keep delivery knowledge coherent while people and AI both participated in the work.

Keeping people in the value chain

I have watched non-engineering professionals worry that AI will replace them, while their most valuable judgment is often excluded from the delivery path. Product, domain, analysis, architecture, quality, operations, and governance professionals have knowledge that cannot be responsibly inferred from a ticket or prompt.

Their value is complementary to AI. When they can participate directly in the value chain, a team can achieve more than it could by relying on a single heroic engineer to reconstruct intent, make hidden decisions, and carry organizational context alone.

The aim

Make human judgment a first-class part of AI-assisted delivery.

I am sharing Specification-First Delivery as a public engineering framework and inviting scrutiny. Its purpose is to help engineering projects make intent, decisions, constraints, execution scope and authority, and evidence available to everyone accountable for the outcome, while keeping human judgment at the core.

  • Treat every accountable role as a direct participant in the software delivery value chain.
  • Use AI to extend professional capability, not to hide or replace responsibility.
  • Build an operating model that can retain knowledge and trust as people, teams, and tools change.

Connect with the creator

Visit Marcus Peck on LinkedIn