Foundry Agent Starter Kit

Build, test, and deploy Microsoft Foundry agents from Python repos.

This package collects the reusable Copilot guidance for Foundry agents. It is named for the user job, not for the SDK. Castia remains the Python package underneath the flow.

What is included

Install

Install from the Castia marketplace in Copilot App when that marketplace is available to your environment:

1. Open Customize.
2. Open Plugins.
3. Add the sethjuarez/castia marketplace if it is not listed.
4. Install Foundry Agent Starter Kit.

For command line setup, install the plugin from the repository subdirectory:

copilot plugin marketplace add sethjuarez/castia
copilot plugin install foundry-agent-starter-kit@castia

This is Copilot plugin distribution, not Agency distribution. Do not use Agency plugin commands or Agency marketplaces for the public Castia path.

Canvas-only testing

Use this when you need to test or share the canvas before the plugin marketplace path is available. The canvas folder is:

plugins\foundry-agent-starter-kit\com.github.copilot\extensions\foundry-agent-playground

Open it as Foundry Agent Playground after installing the extension through Copilot App's extension sharing/install flow.

Manual repo setup

Use this only when you want the prompts and skills committed to a scenario repo instead of installed as a plugin:

New-Item -ItemType Directory -Force .github\prompts, .github\skills
Copy-Item ..\castia\plugins\foundry-agent-starter-kit\prompts\*.prompt.md .github\prompts\
Copy-Item ..\castia\plugins\foundry-agent-starter-kit\skills\* .github\skills\ -Recurse

Use

1. Open a scenario repo in Copilot App.
2. Ask Copilot to build a Foundry agent for that repo.
3. Open Foundry Agent Playground.
4. Click Start local. If the repo has no project endpoint yet, the canvas opens its in-canvas endpoint dialog, then saves non-secret derived values into gitignored local .env files and starts the agent.
5. Check readiness before sending a prompt.
6. Deploy or publish only after explicit approval.