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Spec-Driven

Development

With Kiro

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Transforming Dev Practices with Kiro’s Spec-Driven Tools

with Nikhil Swaminathan, and Richard Threlkeld

Transcript

Chapters

Introduction
[00:01:06]
A stream of consciousness
[00:03:25]
Specifications
[00:08:46]
Demo
[00:17:36]
Context LSP
[00:45:20]
Dev touching code?
[00:47:37]
Spec life cycles
[00:48:37]
MCP servers
[00:49:29]
Journey of learning specs
[00:52:00]
TDD flow
[00:55:10]
Tasks vs requirements
[00:58:54]
The next step
[01:00:37]
Build update
[01:04:23]
Advice
[01:07:22]
Outro
[01:08:15]

In this episode

In this episode of AI Native Dev, host Simon Maple is joined by Nikhil Swaminathan and Richard Threlkeld to discuss Kiro, an agentic IDE designed for spec-driven development. They delve into how Kiro emphasizes specifications as the core artifact in AI-era software, enabling developers to maintain clarity and intent amidst rapid code generation. Discover how this approach improves team coordination, enhances code quality, and ensures that behavior-first design becomes the foundation for sustainable software development.

Rapid “vibe coding” with agentic IDEs lets you ship features in hours, but it also leaves decision-making buried in chat logs and diffs. In this episode of AI Native Dev, host Simon Maple talks with Nikhil Swaminathan (Product Lead) and Richard Threlkeld (Engineer) about Kiro, an agentic IDE built around spec-driven development. They explore why specifications should become the primary artifact of AI-era software development, how Kiro operationalizes behavior-first design, and what practical workflows and lessons they’ve learned after a year of building and research with Amazon science teams.

From Vibe Coding to Spec-Driven Development

The team draws a sharp contrast between vibe coding—rapid, conversational code generation—and the discipline required to build maintainable systems. Vibe coding’s back-and-forth is fast but ephemeral; prompts are point-in-time and tied to transient context. After a flurry of iterations, even solo developers may step back and ask, “What did we build? Why did we choose this?” The rationale and constraints live in a chat stream of consciousness rather than a durable artifact.

Spec-driven development flips that script by making behavior the first-class concern. Instead of using prompts to chase implementations, you define what the system should do, the properties it must uphold, and how it should handle errors. The spec becomes the stable north star that survives code churn. As Simon notes, it’s the difference between a long Slack thread and a shared document everyone actually reviews, aligns on, and treats as the source of truth.

What Kiro Is: An Agentic IDE Built Around Behavior

Kiro’s tagline, an agentic IDE that helps you do your best work, comes with a specific opinionated workflow: center development on specifications. Kiro still gives you the speed of natural-language code generation, but its agent uses specs as the grounding reference when building and evolving code. That way, decisions, assumptions, and constraints are captured explicitly and carried forward rather than lost in chat.

Practically, Kiro turns specs into a living, composable artifact linked to code. The agent can generate implementations, create tests aligned to properties, and produce diffs that map back to spec sections. The goal isn’t “yet another AI editor,” but a way to preserve intent, improve team coordination, and make behavior visible, so you can move fast without erasing the why behind the what.

Specifications Demystified: Behaviors, Properties, and Invariants

Richard frames specifications as descriptions of behavior, not implementation. In formal methods, you might hear about safety properties (what must never happen) and liveness properties (what must eventually happen), or invariants that should hold across system states. For example, a read-after-write consistency guarantee across microservices is difficult to verify by skimming code; it needs to be stated, reasoned about, and checked at a higher level.

Traditional tooling for this includes TLA+, Dafny, and P, or theorem provers like Lean. You might also encounter “design by contract,” where each function declares preconditions, postconditions, and loop invariants. These techniques are powerful but historically gated behind specialized expertise. Kiro’s contribution is to make behavior-centric thinking approachable for everyday development, using specs that mix natural language with structured constraints and machine-checkable elements—then letting the agent generate code, tests, and checks that honor those behaviors.

Composable, Living Specs: What to Put In Them and Why It Matters

A major learning from the Kiro team: specs must be composable documents that blend business and technical context. A useful spec includes real business scenarios and acceptance criteria, interface definitions and data contracts, pseudocode for tricky algorithms, and notes on performance or SLAs. Because they’re modular, you can compose system-level properties from service-level ones and reuse patterns across features and teams.

Specs also benefit from visuals and operational rules. Include sequence or state diagrams (Mermaid/PlantUML works well), define error-handling behavior (idempotency, retries, compensation, timeouts), call out constraints (rate limits, concurrency ceilings), and declare properties/invariants (e.g., “Order status never moves backward,” “Payment cannot be captured after T+7 days”). These become testable and enforceable. Even if you’re not using a full formal model, you can align on terminology and behaviors, then let the agent and CI translate them into tests and checks.

Just as importantly, treat the spec as a versioned artifact in Git. Kiro connects spec sections to generated code and tests, so PRs can be anchored to spec changes. Decision logs live in the spec, not lost in chat. That means onboarding becomes faster, reviews become clearer, and refactors remain aligned to the original intent.

A Practical Workflow in Kiro

The day-to-day flow looks like this:

  1. Draft a spec with scenarios, interfaces, and properties. Start simple—capture the core behavior and a few key invariants.
  2. Ask Kiro to generate or modify code based on the spec. The agent proposes file diffs tied to spec sections.
  3. Generate tests—unit, integration, and property-based tests that exercise the declared behaviors. For instance, if you specified read-after-write, Kiro can scaffold tests that assert that behavior under concurrency.
  4. Run and iterate. When the agent or you propose implementation changes, update the spec and re-generate as needed. Kiro keeps the spec and code in sync.
  5. Review in context. PRs show how diffs satisfy or impact specific spec elements, keeping reviewers focused on behavior rather than just syntax.

Teams can take this further by gating merges on spec coverage and property tests in CI. Over time, you’ll accumulate reusable spec components—common error-handling policies, API patterns, or cross-cutting invariants—that help enforce consistency and reduce redundant reasoning across services.

The Road Ahead: Research to Real-World, and How to Start

Kiro grew out of early research collaborations with Amazon science teams, but its mission is pragmatic: bring the power of behavior-first engineering to everyday developers. Rather than requiring everyone to master esoteric modeling languages, Kiro’s specs are approachable documents that still allow you to encode properties in a way agents and CI can act on.

To get started, pick a feature—not a monolith—and write a one-page spec. Name the core behavior, list 2–3 acceptance scenarios, define inputs/outputs and a few invariants, and specify error-handling. Generate a minimal implementation and tests, then iterate. You’ll quickly discover that the spec becomes a reusable asset that reduces ambiguity, keeps AI-generated code honest, and makes team communication smoother. As the team’s comfort grows, you can gradually add more formal properties, richer diagrams, and stronger CI gates.

Chapters

Introduction
[00:01:06]
A stream of consciousness
[00:03:25]
Specifications
[00:08:46]
Demo
[00:17:36]
Context LSP
[00:45:20]
Dev touching code?
[00:47:37]
Spec life cycles
[00:48:37]
MCP servers
[00:49:29]
Journey of learning specs
[00:52:00]
TDD flow
[00:55:10]
Tasks vs requirements
[00:58:54]
The next step
[01:00:37]
Build update
[01:04:23]
Advice
[01:07:22]
Outro
[01:08:15]