Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#1

Post by janpio » Thu, Oct 16, 2025, 9:36 PM UTC

Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl
martinfowler.com

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#2

Post by yodon » Thu, Oct 16, 2025, 11:46 PM UTC

This pretty much aligns with my experience with SpecKit - I'm excited by it, and enjoying working with it, but have had a hard time finding guidance on advanced real world use cases.

All the tutorials I've found are little more than "here's how to install it - now let's make a todo list app from scratch!!"

Would be great to see how others are handling real world use cases like making incremental improvements or refactorings to a huge legacy code base that didn't start out as a spec driven development hello world project.

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#3

Post by gsadaka » Fri, Oct 17, 2025, 1:54 AM UTC

yodon wrote: post #2

This pretty much aligns with my experience with SpecKit - I'm excited by it, and enjoying working with it, but have had a hard time finding guidance on advanced real world use cases. All the tutorials I've found are little more than "here's how to install it - now let's make a todo list app from scratch!!" Would be great to see how others are handling real world use cases like making incremental improvements or refac…

I have also struggled to find real world examples for these approaches.

Following a BDD approach with a coding CLI works a lot better, as it documents the features as code rather than verbose markdown files no one will read.

Having a checklist for an AI to follow makes sense, but that's why agents.md exists. Once the coding patterns and NFRs are documented in it, the agent follows them as well as they would follow a separate markdown spec.

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#4

Post by iamdeedubs » Fri, Oct 17, 2025, 2:28 AM UTC

In my experiments with SpecKit I was always left wondering "when does it merge all this specs into a single ground truth". I never got there and it felt like a huge missing step.

Now I'm left trying to define/design what a "spec" for communication between humans and coding agents would look like, to power what Birgitta called spec anchored.

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#5

Post by tharkun__ » Fri, Oct 17, 2025, 3:54 AM UTC

    Distinguished Engineer and AI-assisted delivery expert at Thoughtworks.

And then talk about memory banks. Yeah, I recognize that from work where "AI has taken off" as well.

Guess what: As memory banks grow or accumulate the AI gets confused and doesn't quite deliver.

So far, a human that actually knows their product still prevails and is necessary to actually guide any AI effort. AIs have been trying to bullshit me so much it's not even funny any longer. Of course they all apologize and figure out reality when I guide them but that doesn't change the facts. And I simply can't read all the documents the AIs write for themselves to correct all of them and even if I did I wouldn't be sure enough that they'd improve significantly enough for me to try and spend this mind bogglingly boring amount of time to help this thing that's supposed to take my job ....

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#6

Post by mrbonner » Fri, Oct 17, 2025, 4:05 AM UTC

tharkun__ wrote: post #5

Distinguished Engineer and AI-assisted delivery expert at Thoughtworks. And then talk about memory banks. Yeah, I recognize that from work where "AI has taken off" as well. Guess what: As memory banks grow or accumulate the AI gets confused and doesn't quite deliver. So far, a human that actually knows their product still prevails and is necessary to actually guide any AI effort. AIs have been trying to bullshit me s…

It’s on there, right? And that “thought leader” title they’ve put on LinkedIn? I’m still scratching my head trying to figure out what that means!

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#7

Post by esafak » Fri, Oct 17, 2025, 4:17 AM UTC

I don't know why SDD suddenly became a thing, but FWIF, I find value in spec files to make sure I know what I'm going to get, and to track progress when I break up projects into smaller tasks. Mind you, I don't use any tool or framework; just a simple Markdown file. I don't see value in the formalism beyond that.

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#8

Post by ctxc » Fri, Oct 17, 2025, 6:25 AM UTC

I was excited to use spec-kit. I had to dump it eventually when it generated steps that were the equivalent of Tony Stark building a robot from scratch in a cave when "just screw this bolt on" would have sufficed.

Always made it too complex, and at some point it wasn't worth correcting it anymore.

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#9

Post by hatmanstack » Fri, Oct 17, 2025, 7:04 AM UTC

In my experience with Kiro's spec-driven approach it generated massive task lists (12+ tasks with 4+ sub-tasks each). The workflow was decent but it deleted code unpredictably and wouldn't revert changes. Being a full IDE likely diverts resources to UI edge cases rather than core reliability.

So much simpler to just iterate without the puzzle box of tasks. "a sledgehammer to crack a nut"

Re: Understanding Spec-Driven-Development: Kiro, Spec-Kit, and Tessl

#10

Post by iamsaitam » Fri, Oct 17, 2025, 7:53 AM UTC

> When I asked Kiro to fix a small bug (it was the same one I used in the past to try Codex), it quickly became clear that the workflow was like using a sledgehammer to crack a nut. The requirements document turned this small bug into 4 “user stories” with a total of 16 acceptance criteria, including gems like “User story: As a developer, I want the transformation function to handle edge cases gracefully, so that the system remains robust when new category formats are introduced.”

Kiro, your new corporate project manager.