Show HN: Kastor – Terraform-style specs for AI agents

by weirdguy • 14 days ago

33 21 14 days ago

weirdguy8• 14 days ago

hey HN, it's first time posting something here.

I’m building Kastor: Go CLI/declarative language/config for AI agents.

the motivation: agent definitions often end up spread across framework code, prompt files, tool files/mcps, platform UI settings, and env vars. that makes them hard to review, diff, reproduce or move.

Kastor is an attempt to put a source-of-truth layer above that.

right now the working proof of concept is narrow:

- .agent / .tool / .prompt files - HCL parser + validation - dependency/reference checks - LangGraph codegen - runnable weather example - runnable content scheduler example

the long-term direction is Terraform-ish:

- build: compile to framework code - plan/apply: reconcile hosted platform agents - state: track remote resources and detect drift

I’m deliberately not trying to build another agent runtime. the thing I’m trying to validate is whether agents need something closer to IaC: versionable, reviewable, declarative source of truth.

would appreciate any kind of feedback, especially on the language/design.

handfuloflight3• 14 days ago

The website is down?

weirdguy8• 14 days ago

oh, it's not, just root domain (non-www) without redirect

handfuloflight3• 14 days ago

That's not working either.

Leewen2• 14 days ago

works for me. terraform for agents? neat

weirdguy8• 14 days ago

thanks — that’s the direction. current version is still just validate + LangGraph codegen, but plan/apply/state is the part I’m trying to get to next

Leewen2• 14 days ago

empath75• 14 days ago

The problem right now with something like this is you're trying to nail jello to a wall. People haven't figured out what an agent is yet, and trying to crystalize what people happen to be doing right now means in a few months, you're going to be obsolete.

weirdguy8• 14 days ago

I agree with you

don't think the "agent" abstraction is stable enough to standardize the behavior/runtime layer yet.

thing I'm trying to test is smaller: is that possible to standardize the outer contract around agents?

what inputs does it accept? what outputs does it promise? what model does it use? what prompt/template does it depend on? what tools can it call? what target should it be built or applied to?

so here it is intentionally not trying to describe the full control loop or become a runtime. it's more like a source-of-truth layer for the parts that are already showing up everywhere, even if the runtime patterns keep changing underneath.

I might be wrong, but my bet is that the runtime layer will keep changing, while the need for reviewable/diffable agent contracts will not.

reactordev2• 14 days ago

You mean Claude…

giancarlostoro2• 14 days ago

Claude is a model, an agent is more like the full solution. Some would call Claude Code itself an agent. Agents do things, models are just models until you use them.

whattheheckheck3• 14 days ago

Why not just make an actual terraform module?

weirdguy8• 14 days ago

Good question

For hosted agents only, a Terraform provider probably makes sense.

The reason I didn’t start there is that Kastor has two paths:

1 - build: compile the spec into framework code, e.g. LangGraph

2 - plan/apply for agents hosted on platforms

Terraform is great for the second path, but awkward as the primary tool for the first one. I want the same agent spec to be able to produce code or manage a remote agent.

So I can imagine a Terraform provider being one target later, but I don’t think Terraform itself is the right tool/place for the whole thing.

whattheheckheck3• 12 days ago

Im wondering if you can expand it using TLA+ some how. I like the declarative language that compiles down to langgraph idea. Langgraph or hamilton/burr are two strong contenders for state machines. Maybe mix dbos or Temporal in there and you could almost have something to full declare the whole system

Show HN: Kastor – Terraform-style specs for AI agents

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