FievelBeta
Designed for:Fievel plugin for Claude CodeFievel plugin for CodexFievel repository for GitHub Copilot

The forever content system

Bring your product, content, and design guidance, and Fievel helps turn them into a content system you can keep building and improving.

Get startedLearn more

Fievel system architecture

shapesgroundsguidesinformsassessmaintainsapprovespermitsProduct contextSourcesGovernanceStandardsAI behaviorSkillsEvaluationsTools
shapesgroundsguidesinformsassessmaintainsapprovespermitsProduct contextSourcesGovernanceStandardsAI behaviorSkillsEvaluationsTools

Select a topic to learn more.

Example conversation~/my-project
YouHi
FievelHi, I'm Fievel. I'm here to help you set up your content system. Are you starting from scratch or bringing existing guidelines?
YouI have a style guide in docs/style-guide.md, but I need help setting up the rest.
  • Readdocs/style-guide.md42 lines
  • fievel_get_lessonusing-existing-guidelinesLoaded
FievelWe can build on that. Your guide already covers voice and terminology, so we'll keep it as the source for your standards and connect knowledge sources, AI behavior, and evaluations around it. What product or experience is this for?
YouAn AI experience for our product. I want it to use our voice and follow our rules.
  • fievel_initmy-content-system7 draft files
  • fievel_validatemy-content-systemStructure valid
FievelI've set up my-content-system with draft files. Nothing is approved until you decide. Let's start with your product context.
Who is this experience for?Selected
  • fievel_get_templateproductLoaded
  • Editmy-content-system/product.jsonAudience added
FievelGot it. What do existing customers ask about most, and is there anything the AI should never do for them?
YouBilling and plan changes, mostly. Refunds come up too, but only our support team can approve those.
  • fievel_get_lessonai-behaviorLoaded
  • Editmy-content-system/behavior.json1 boundary added
FievelI added a boundary: the AI can explain your refund policy, but it hands every refund request to your support team. Want a check that tests it?
YouYes, please.
  • Editmy-content-system/evaluation.json1 scenario, 2 checks
  • fievel_validatemy-content-systemStructure valid
FievelDone. There's now a scenario where a customer asks for a refund, with checks that link back to your boundary. Save a response from your AI and I'll run them.

Use your coding agent

Fievel is a plugin for Claude and Codex, with built-in skills and tools your agent can use directly. Or clone the repository in VS Code and use it with GitHub Copilot.

Claude Code

Install the Fievel pluginGet Claude Code
Learn more

Install the Fievel plugin, then start a chat in your project folder and ask Fievel to get started. You can also open the cloned repository and type /getting-started.

Local MCP serverFievel's tools run on your computer. They work only inside your project folder, never overwrite your files, and send nothing online.

Codex

Install the Fievel pluginGet Codex
Learn more

Install the Fievel plugin, then start a chat in your project folder and ask Fievel to get started. You can also open the cloned repository and type $getting-started.

Hosted MCP serverFievel's tools offer lessons, templates, and checks. Your agent sends only what each request needs, and the server keeps nothing: no accounts, storage, or content logs.

GitHub Copilot

Use the Fievel repositoryGet Copilot in VS Code
Learn more

Open the cloned repository in VS Code with GitHub Copilot in agent mode. Ask it to read AGENTS.md and start Fievel.

Repository toolsCopilot follows Fievel's instructions and skills in the repository and runs its Python tools in your terminal. Everything stays on your computer.

Evaluate as you build

Fievel turns your rules into tests, so you can keep your AI's quality high as your system grows.

  • Every check links back to a rule
  • Results you can rerun after every change
  • Continuously improve the performance of your system

Fievel evaluation framework

Select a step to see how it works.

Get started now

Install the plugin

  1. Choose Claude Code or Codex

    The plugin works in both. For GitHub Copilot, clone the repository instead.

  2. Have Python ready

    Python 3.10 or later on your computer. Fievel sets up its one dependency in your project folder, with your permission.

  3. Install the plugin

  4. Plugin install details ↗

Clone the repository

  1. Choose your coding agent

    Use Codex, Claude Code, or GitHub Copilot in VS Code.

  2. Install the local tools

    Have Git and Python 3.10 or later available on your computer.

  4. Full setup instructions ↗

The last content system you'll ever need.