Grain

Define AI agents as data, not prompts.

Most agent frameworks treat personality and behavior as strings you paste into a system prompt. Grain treats them as a structured, immutable data type with real operations: build, merge, diff, query, serialize.

You define an agent's personality as numbers. Grain turns them into behavioral directives using 5-level graduated semantic anchoring. The same agent definition produces different prompts per channel.

grain.reallyartificial.org | GitHub | PyPI (grain-sdk)

Install

npm install @reallyartificial/grain

30-second version

import { Grain } from "@reallyartificial/grain"

const agent = Grain.create("support-bot", { name: "Alex", description: "Customer support agent" })
  .setPersonality("warmth", 0.9)      // 0-1 float, maps to real behavioral directives
  .setPersonality("formality", 0.3)
  .setPersonality("confidence", 0.8)
  .addBoundary({ description: "Never share internal pricing data", category: "data", enforcement: "hard", onViolation: "refuse" })

// Natural language system prompt, ready for any LLM
agent.toPrompt()

// Same agent, tuned for Slack
agent.toPrompt("slack")

// Clean YAML, stripped of metadata, usable directly as a prompt
agent.toString()

What the personality numbers actually do

setPersonality("warmth", 0.9) doesn't just store 0.9. It maps to a specific behavioral directive:

This works across 8 dimensions: formality, warmth, humor, assertiveness, verbosity, confidence, concreteness, urgency. Each has 5 graduated levels. The directives are grounded in the SAC framework for trait decomposition.

Immutable by design

Every operation returns a new Grain. The original never changes.

const base = Grain.create("bot")
const friendly = base.setPersonality("warmth", 0.9)

base.personality.warmth     // 0.5 (default, unchanged)
friendly.personality.warmth // 0.9

Merge and diff agents

const a = Grain.create("bot-a").setPersonality("warmth", 0.3)
const b = Grain.create("bot-b").setPersonality("warmth", 0.9)

const merged = a.merge(b)   // b wins on conflicts
const changes = a.diff(b)   // { "voice.personality.warmth": { before: 0.3, after: 0.9 } }

Works with any LLM

import { Grain } from "@reallyartificial/grain"
import OpenAI from "openai"

const agent = Grain.load("./support.agent.yaml")
const client = new OpenAI()

const response = await client.chat.completions.create({
  model: "gpt-4o",
  messages: [
    { role: "system", content: agent.toPrompt() },
    { role: "user", content: "I need help with my order" }
  ]
})

Swap OpenAI for Anthropic, Gemini, Ollama, or anything that takes a system prompt. Grain produces strings, not vendor lock-in.

Load from YAML

specVersion: "1.0"
id: support-bot
version: 1.0.0
meta:
  name: Alex
  description: Customer support agent

That's a valid Grain file. Four required fields. Everything else has sensible defaults.

const agent = Grain.load("./support.agent.yaml")

CLI

npx @reallyartificial/grain validate agent.yaml
npx @reallyartificial/grain generate agent.yaml --channel slack
npx @reallyartificial/grain info agent.yaml

API

Constructors: Grain.create(id, opts?) | Grain.from(yamlOrJson) | Grain.load(filePath) | Grain.of(spec)

Mutations (return new Grain): addRule / removeRule / addBoundary / removeBoundary / addTool / removeTool / addSkill / removeSkill / addExpertise / removeExpertise / setPersonality / set / get / merge

Output: toString(channel?) clean YAML | toPrompt(channel?) natural language | toYAML() full YAML | toJSON() full JSON | validate() | diff(other)

Presets: Presets.personality.professional | .friendly | .expert | .creative | .executor

Full API docs at grain.reallyartificial.org

License

MIT