supply-chain-security

supply-chain-security is a skill for Claude Code from the-open-agent/oss-skills. It costs 100 tokens per session (2,154 once invoked), scanned A, original, Apache-2.0.

A set of practices for protecting an open-source project's software supply chain—the dependencies, build systems, releases, and people involved in delivering its code.

In plain words
What is it for?
Use it to write security guidance, receive vulnerability reports privately, restrict GitHub Actions, pin dependencies, create software bills of materials, record build origins, and sign releases.
Why use it?
It helps reduce the risk that attackers compromise a maintainer account, dependency, build process, contribution, or installation step and then reach users.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is Report privately via [GitHub Security Advisories](../../security/advisories/new).

Part of the oss-skills plugin — 18 skills shipped together

Good fit Use it to write security guidance, receive vulnerability reports privately, restrict GitHub Actions, pin dependencies, create software bills of materials, record build origins, and sign releases.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/the-open-agent/oss-skills
agentmods
npx agentmods add skills/the-open-agent/oss-skills/supply-chain-security

Made for: Claude Code.

Or install oss-skills, the plugin that ships this one along with the rest of its 18 skills.

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 supply-chain-security

README.md
[![agentmods](https://agentmods.dev/badge/skills/the-open-agent/oss-skills/supply-chain-security/github.svg)](https://agentmods.dev/skills/the-open-agent/oss-skills/supply-chain-security)
Your own site
<a href="https://agentmods.dev/skills/the-open-agent/oss-skills/supply-chain-security"><img src="https://agentmods.dev/badge/skills/the-open-agent/oss-skills/supply-chain-security/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for supply-chain-security

Your own site · 80×15
<a href="https://agentmods.dev/skills/the-open-agent/oss-skills/supply-chain-security"><img src="https://agentmods.dev/badge/skills/the-open-agent/oss-skills/supply-chain-security.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,154 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00100 $0.02154
Opus 5 $0.00050 $0.01077
Sonnet 5 $0.00020 $0.00431
Haiku 4.5 $0.00010 $0.00215

Measured 11d ago against content hash 1f901f4f6215, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

supply-chain-security scanned grade A with 0 findings 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 11d ago.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/supply-chain-security/SKILL.md · 203 lines

How it starts

The opening of the file, as written. The whole thing — 203 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Supply Chain Security

Your project's security posture affects everyone downstream. A popular package is a high-value target precisely because compromising it is cheaper than compromising its users individually.

The realistic threat model

Ranked by observed frequency in actual incidents, not by drama:

  1. Compromised maintainer account — phishing, credential reuse, no 2FA. The single most common root cause of package compromise.
  2. Malicious dependency — typosquat, or a legitimate package taken over via a maintainer handoff to a stranger who asked nicely.
  3. Compromised CI — a workflow with excessive permissions, an unpinned third-party action, pull_request_target executing fork code.
  4. Malicious contribution — a subtle backdoor in a PR from a patient contributor who spent months building trust.
  5. Build-time injectionpostinstall scripts, setup.py executing at install, compromised build servers.

Note what is not at the top: vulnerabilities in your own code. Those matter, but the supply chain is where the leverage is.

Baseline hardening

Do all of these. Together they take an afternoon and remove most of the realistic risk.

Accounts

  • Hardware 2FA (WebAuthn) on GitHub and every package registry, for every maintainer. SMS 2FA is not sufficient against the phishing that actually happens.
  • Registry publishing via OIDC/trusted publishing instead of long-lived tokens.
  • Audit org membership and repo access quarterly. Remove inactive maintainers' publish rights, kindly and explicitly — this is not a demotion, it is hygiene.

Repository

  • Branch protection on main, including for admins.
  • Signed commits/tags for releases (git config commit.gpgsign true; Sigstore gitsign avoids GPG key management entirely).
  • Enable private vulnerability reporting: Settings → Security → "Private vulnerability reporting". This gives researchers a channel that is not a public issue.
  • Enable Dependabot alerts, secret scanning, and push protection.

Read the full file on GitHub · 203 lines

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. 11d ago First seen · 203 lines · 100 tokens per session scan A 1f901f4f6215

Subscribe to this mod's changes

supply-chain-security is a skill published in the GitHub repository the-open-agent/oss-skills (5 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 100 tokens to every session and 2,154 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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