> Canonical guide: https://developers.foxlight.ai/build/agent-skill/
> Contract snapshots: Skulk 2.0.0 (b0af39c79b6b7102b2478062904f1d7cc8619975); SDK 0.4.0 (31bb090b8f64689f87514e48385e22b6ad94a6c2). Check the installed runtime when versions differ.
# Build with your agent
Give your coding agent the **Build on Skulk** skill. It explains how to build applications on the fabric using the capability SDK and Skulk's inference APIs, with bundled public references and complete teaching examples.
Looking for setup or client integration? [Choose a task in the Agents hub](https://developers.foxlight.ai/agents/). To use this skill for one task, give your agent the direct SKILL.md URL; its supporting references are published beside it.
Download the skill — v0.1.0 ZIP · SHA-256 checksum
## What it helps your agent do
- Choose an ordinary API client, a managed capability or an in-process extension.
- Define descriptors and implement startup, health, calls and shutdown.
- Use all four I/O modes without confusing stream admission with media delivery.
- Build durable jobs with cancellation, idempotency and honest recovery.
- Connect inference, application storage and discoverable interfaces.
- Test the integration and explain what still needs a real installed runtime.
The skill includes the SDK's public signatures, a small capability HTTP schema snapshot, a complete managed echo example and the local operation workshop. References are loaded as needed instead of filling every conversation with the entire manual.
## Install it
Use an agent that supports folder-based skills with a `SKILL.md` entry point, or its ZIP import feature if available.
1. Download and extract the ZIP.
2. Put the **whole `build-on-skulk` folder** in the skill directory configured for your agent. Keep `references/`, `agents/` and `source-manifest.json` with `SKILL.md`.
3. Reload the agent's skills or start a new session, following that agent's instructions.
4. Ask it to use `build-on-skulk` for your application.
For Codex, the default user skill location is `~/.codex/skills/build-on-skulk/`; a custom `CODEX_HOME` changes that base location. Invoke it as `$build-on-skulk`. Other agents may use different directories and invocation syntax. This is a portable folder, not a claim that every agent supports the same import UI.
Downloading this skill does not install the SDK, launch Skulk or change your cluster. Check [SDK package availability](https://developers.foxlight.ai/build/get-sdk/) separately. The archive contains Markdown, JSON and YAML; it has no SDK implementation or executable installer.
## Try a concrete prompt
```text
Use $build-on-skulk to build a managed capability named storyboard.plan.
It should accept a scene description and return a typed shot list using
an already-mounted chat model on my Skulk cluster. Start with fake API tests,
keep the model caller separate from the child transport, and explain each
SDK boundary. Do not mount a model or publish the package yet.
```
Or start without inference:
```text
Use $build-on-skulk to build my first read-only echo capability.
Help me understand the descriptor, host startup, health checks and shutdown.
Run the tests available locally and tell me which installed-host checks remain.
```
Once that works, follow the [Video Studio tutorial](https://developers.foxlight.ai/build/tutorials/video-studio/) for a larger application.
## Versions and updates
Version 0.1.0 documents SDK **0.4.0**, Python **3.13+**, managed protocol **4**, and the site's pinned **Skulk 2.0.0 next-channel** API snapshot. Protocol-3 unary compatibility is explained separately. Exact source revisions are included in `source-manifest.json` inside the archive.
The bundled references work offline. For a different installed version, your agent should check that version's public SDK interface and API contracts before changing code. The skill supplements [Foxlight Docs](https://docs.foxlight.ai/) and the [SDK reference](https://developers.foxlight.ai/build/sdk/); it does not silently track your running cluster.
The checksum detects a changed download; it is not a signature or a separate trust root. Revisit this page for newer skill versions and replace the complete folder together so instructions and references remain consistent.