headless-claude-code SKILL.md skillA
headless-claude-code from vellum-ai/vellum-assistant is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add vellum-ai/vellum-assistant/headless-claude-code@git:20260807.cd12932Pins git:20260807.cd12932 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- vellum-ai/vellum-assistant
- Path
skills/headless-claude-code/SKILL.md- Versions recorded
- 3
- Latest version
- git:20260807.cd12932, committed Aug 7, 2026
- First version recorded
- Apr 24, 2026
- Size
- 17,171 bytes
- Repository stars
- 1,467
- License
- MIT
Reference guide for running Claude Code in third-party headless, container, and CI environments. Covers auth strategies, interactive mode pitfalls, tmux orchestration, root user workarounds, and git auth without SSH agents or keychains.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Headless Claude Code
Running Claude Code outside a desktop terminal — in Docker containers, CI runners, cloud
VMs, or orchestrated by another process — is full of undocumented friction. This guide
covers everything we've learned getting CC to work reliably in these environments.
---
## 1. Authentication
CC tries multiple auth strategies in a fixed priority order. Understanding this chain is
the key to headless auth.
### Priority Order (highest → lowest)
1. **Cloud provider ambient credentials** — AWS Bedrock, GCP Vertex (auto-detected)
2. **`ANTHROPIC_AUTH_TOKEN`** — raw bearer token for Anthropic's API
3. **`ANTHROPIC_API_KEY`** — direct API key (pay-per-token, no Pro subscription features)
4. **`apiKeyHelper`** — executable that prints a token to stdout (set via `--settings`)
5. **`CLAUDE_CODE_OAUTH_TOKEN`** — OAuth token (Pro/Team subscription)
6. **`/login`** — interactive browser OAuth dance (unusable in headless)
### Recommended: `apiKeyHelper`
The most flexible headless strategy. Point CC at a script that returns a valid token:
```json
{
"apiKeyHelper": "/path/to/your-auth-script"
}
```
…Read the whole file at its exact version.
How to install
mdr add vellum-ai/vellum-assistant/headless-claude-code@sha256:8ae0c0dc56852464The line at the top of this page pins the label git:20260807.cd12932, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_uxige5f5zvxjp7fv)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 3 versions of this file, between Apr 24, 2026 and Aug 7, 2026, about one every 53 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260807.cd12932 latest | 2026-08-07 | cd12932 | 17,171 B | A | view · diff |
| git:20260603.ff934d9 | 2026-06-03 | ff934d9 | 17,039 B | A | view · diff |
| git:20260424.8098008 | 2026-04-24 | 8098008 | 17,011 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (17171 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
vellum-ai/vellum-assistant · 1,467 stars · license MIT · pushed 2026-10-29 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_uxige5f5zvxjp7fv GET https://markdownregistry.com/api/v1/resolve?ref=vellum-ai/vellum-assistant/headless-claude-code GET https://markdownregistry.com/api/v1/blob/8ae0c0dc56852464e722677074457dd556681bde10b5a577462598bc146b0820
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
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