Show HN: Kastor – Terraform-style specs for AI agents
This covers a coding tool or code-capability update — useful for developers assessing workflow changes and reusable value.
Kastor offers a vendor-neutral, versionable, and reviewable solution for defining AI agents. It uses a typed, declarative spec in HCL for agents, tools, and prompts.…
Kastor is "Terraform for AI agents." Agents today are defined imperatively inside frameworks (LangGraph, CrewAI) or clicked together in platform UIs (OpenAI Assistants, Bedrock Agents) — there is no vendor-neutral, versionable, reviewable source of truth. Kastor provides one: a typed, declarative spec (.agent, .tool, .prompt files in HCL) and a Go toolchain with two paths — kastor build generates runnable projects for target frameworks, and kastor plan / kastor apply reconcile agents as long-lived resources on hosted platforms, with state, diffs, and drift detection.
The full design lives in SPEC.md .
Status
Kastor is an early proof of concept.
Working today:
- parse .agent, .tool, .prompt, and kastor.hcl
- validate references and prompt variables
- build runnable LangGraph projects
- examples: weather agent , content scheduler agent
Planned for v0:
- kastor plan/apply
- local state file and drift detection
- Deploy to aws/azure platforms.
This is not another agent runtime/framework.
Install
Homebrew:
brew tap weirdGuy/tap && brew install kastor
Install script (verifies the release checksum, installs to /usr/local/bin or ~/.local/bin, never sudo):
curl -fsSL https://raw.githubusercontent.com/weirdGuy/kastor/main/scripts/install.sh | sh
With Go 1.26+:
go install github.com/weirdGuy/kastor/cmd/kastor@latest
Or download an archive for your platform from the releases page , verify it against checksums.txt, and put the kastor binary on your PATH.
Quickstart: build the weather example
Prerequisites: Go 1.26+, Python 3.11+, an OpenAI API key, and a Tavily API key (the example's search tool runs against Tavily's hosted MCP server).