vellum-github-app-setup

vellum-github-app-setup is a skill for Claude Code, Codex from vellum-ai/vellum-assistant. It costs 61 tokens per session (2,790 once invoked), scanned C, original, MIT.

A setup guide for creating a GitHub App that gives the assistant its own identity in a GitHub organization.

In plain words
What is it for?
Use it to create the app, install it on selected organization repositories, store its credentials, and enable authenticated Git operations.
Why use it?
It separates automated commits, pull requests, and comments from the user's personal GitHub account while providing the required repository permissions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create the app, install it on selected organization repositories, store its credentials, and enable authenticated Git operations.

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Install with agentmods
npx agentmods add skills/vellum-ai/vellum-assistant/vellum-github-app-setup
About the project

Vellum Assistant is a personal AI assistant that remembers information about users, learns their preferences, and takes actions across connected apps. It is intended for people who want an assistant that can manage conversations, unfinished work, and proactive notifications over time. The catalogue skills, hooks, instruction, and setting configure or extend how the assistant works.

vellum-ai/vellum-assistant · 1,201 stars · on GitHub · vellum.ai

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add vellum-ai/vellum-assistant --skill vellum-github-app-setup
Clone the repo
git clone --depth 1 https://github.com/vellum-ai/vellum-assistant

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for vellum-github-app-setup

README.md
[![agentmods](https://agentmods.dev/badge/skills/vellum-ai/vellum-assistant/vellum-github-app-setup.svg)](https://agentmods.dev/skills/vellum-ai/vellum-assistant/vellum-github-app-setup)
Your own site
<a href="https://agentmods.dev/skills/vellum-ai/vellum-assistant/vellum-github-app-setup"><img src="https://agentmods.dev/badge/skills/vellum-ai/vellum-assistant/vellum-github-app-setup.svg" alt="Measured on agentmods" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,790 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 5 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Privilege Escalation · line 49
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 83
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 92
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 98
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • medium Data Exfiltration · line 118
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00061 $0.02790
Opus 5 $0.00030 $0.01395
Sonnet 5 $0.00012 $0.00558
Haiku 4.5 $0.00006 $0.00279

Measured 4d ago against content hash 46d8018a58f1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade C, and why

vellum-github-app-setup scanned grade C with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/create-github-app.py, scripts/gh-app-token.mjs), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Harvests environment variableshighData exfiltration

Enumerating or grepping the environment for keys collects credentials unrelated to what the mod says it does.

The credentials JSON from Step 1 lives on the user's host. Store the non-secret identifier fields inline, then collect the secret fields from the user via the secure prompt.
skills/vellum-github-app-setup/SKILL.md · 254 lines

How it starts

The opening of the file, as written. The whole thing — 254 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Overview

This skill creates a GitHub App under a GitHub organization, giving the assistant its own bot identity for git operations. After setup, commits, PRs, and comments will attribute to <app-name>[bot] instead of the user's personal account.

Total manual effort: 7 interactions — Continue to GitHub → Create App → 3 secure credential prompts → Install on repo → (optional) upload avatar. Everything else is automated.

Note: This skill currently supports GitHub organizations only, not personal accounts.

What Gets Created

  • A GitHub App owned by the org (not the user's personal account)
  • Installation on selected repositories with configurable permissions (default: contents:write, pull_requests:write, checks:read, metadata:read)
  • Credentials stored in the assistant's encrypted vault (7 fields)
  • Token helper script at bin/gh-app-token.mjs (in the workspace root) for refreshing auth tokens

Prerequisites

  • User must be an admin of the GitHub organization
  • User must be logged into GitHub in their browser
  • The assistant credentials CLI must be available
  • Python 3 on the host machine (for the manifest flow server)
  • bun in the container (for the token helper script)

Setup Flow

Step 1: Create the GitHub App

Run the manifest flow script on the user's host machine (it needs to open a browser and catch a localhost callback):

python3 scripts/create-github-app.py \
  --org=ORG_NAME \
  --name=APP_NAME \
  --url="https://example.com" \
  --output=/tmp/github-app-credentials.json

This starts a local server on localhost:29170, opens the browser, and guides the user through two clicks:

  1. "Continue to GitHub" — submits the pre-filled manifest form
  2. "Create GitHub App for ORG" — confirms on GitHub's page

The callback server catches the redirect and exchanges the code for credentials automatically. The credentials JSON is saved to --output.

Important manifest details (learned the hard way):

Read the full file on GitHub · 254 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 254 lines · 61 tokens per session scan C 46d8018a58f1

Subscribe to this mod's changes

vellum-github-app-setup is a skill published in the GitHub repository vellum-ai/vellum-assistant (1,201 stars, last pushed yesterday), licensed MIT. It adds 61 tokens to every session and 2,790 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 1 finding (harvests environment variables). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.