Ask HN: What Happened to Spec-Driven Development?

For a minute, it seemed like SDD tools like Kiro, OpenSpec/SpecKit, Tessl were gonna be the future of coding agents. It seemed like a good idea to me at least, and it resolved a lot of the issues people were having with coding agents kinda just going off and doing their own thing.

Nowadays though, it seems like all the SDD tools have kinda fallen off but all of the complaints remain—coding agents still improvise code that doesn’t fall under the user’s requirements all the time. Did we all just collectively decide that /plan mode was enough?

On the one hand I want to believe in spec driven development - I think there’s this awkward gap between code and not code that is the cause of the sort of “code review crisis” that gets written about a lot. And

But the reason you don’t have to read assembly when you write in a higher language is that, over time that abstraction has become largely complete and is deterministic.

Like when you write I dunno Python to add two numbers and calls class, that spec is universal and agreed upon. ~99.99% of the time when you read Python documentation, and replicate it, it does what the designers intended.

Spec driven development is none of those things. So while I’d like to see people experiment with higher level languages, I think many folks find there’s now way to consistently reconcile the spec with the code.

As much as no one wants to read the code anymore, it seems like most people seem to agree it’s the only source of truth.

Agents are already too good, the models improved

Nowadays you can just start with a plan.md and add everything you want there, verification etc

And you can build a loop to verify/validate it in case its a big/long-running plan

I don't have the problems you mentioned that the models aren't able to follow instructions throughoutly, they do make some mistakes, but it's up to you to set up a process that would work for your codebase to understand that the mistakes were made and need to be fixed, that can be done in a loop for example.

Agents are getting very good also on inventing features. Features that the dev might even like, or might just ignore they exists...unless looking at the code or asking the agent specifically.

Specs are great to identify what has been implemented without explicit control, and to get control over it - if needed.

Also, I think specs are a good way to have bird's-eye of the whole project, for sanity and long term maintanance.