Praecise Harness: a folder is an app, and the app is an agent.
Harness is the open framework for AI apps. Agents, tools, memory, grounding, model choice and resumable workflows are the framework itself, not additions to it. Every app is served as a chat page, a REST API, an MCP endpoint and an A2A peer.
In short
Praecise Harness is the open framework for AI apps: a folder is an app, served as a chat page, a REST API, an MCP endpoint and an A2A peer. The platform also places Node apps, static exports and container images. Start with npx @praecise/harness init my-app.
00
At a glance.
Open source
Apache-2.0.
github.com/Praecise/praecise-harness, npm @praecise/harness.
Runtime
Node 22 or newer.
The runtime has no dependencies of its own.
In use
Praecise runs on it.
Harness runs Praecise's agents.
01
A folder is an app.
One folder, one file per agent, and nothing registered by hand. A file's name is its name.
npx @praecise/harness init my-app
cd my-app && npm install
npx @praecise/harness dev
my-app/
agents/support.ts
functions/refund.ts
memory/faq.md
.env
// agents/support.ts
import { agent } from "@praecise/harness";
export default agent({
role: "Customer support for Acme.",
tools: ["refund"],
});The dev server serves a chat page for each agent, a REST API and an MCP endpoint.
02
AI-native by design.
- 01
Agents as files
A role and the tools it may use.
agents/support.ts is the agent support, served at /support.
- 02
Model choice derived
A quality dial, not a model id.
fast, balanced or best decides how much room the request has; the cheapest capable model answers first.
- 03
Grounding
Answers come from your files.
memory/ is read by every agent. Large folders get an outline and a read_knowledge tool.
- 04
Memory and selves
An agent can remember who it is.
An agent can declare a self that persists, with a provider you choose.
- 05
Resumable workflows
Steps that stop for a person.
Approve gates and a journal that can resume, recover or fork a run.
- 06
Tools by protocol
MCP servers and OpenAPI documents.
Any MCP server or OpenAPI document becomes tools, behind a guard.
- 07
Stores
SQL, document, time-series, vector.
Declared in stores/ and served through one shape. Graph is not served.
- 08
Served every way
Chat, REST, MCP, A2A, AG-UI.
One app, every kind of caller, plus llms.txt and ai.json.
03
Harness on Praecise.
Build
Harness, Engine, Furcate.
Harness is the app. Engine speeds up the model under it. Furcate is the open base underneath.
Place
Like any Node app.
Place the folder behind the edge. With one key it uses the models, database and object storage Praecise Cloud provides.
Operate
Same releases.
Health-checked releases, rollback, secrets kept outside the release.
04
Other frameworks the platform places.
- 01
Node apps
The Cloud section of Praecise Spaces is deployed on this platform.
- 02
Static exports
praecise.com and praecise.cloud are Next.js static exports placed as files.
- 03
Container images
An app that ships as a container image is run from the image.
- 04
Agent applications
An agent application is placed like any other app and is reachable by other agents.
05
Next pages.
06
Praecise accounts are by invitation. Open the console, or talk to us.
New to Praecise Cloud? Accounts are set up with the Praecise team: talk to us, then sign in to the Cloud section of Praecise Spaces with an email code.