# Pin Github Actions

> The mechanizable slice of CI supply-chain hardening, enforced at two points: at commit (the git hook, over staged changes) and at agent tool-use (over a tool call's arguments, as the agent writes) -- a workflow that references a third-party GitHub Action by a movable ref -- a branch or a version tag -- instead of a full 40-character commit SHA. A tag like v4 or a branch like main can be re-pointed at new code after review, so the action that runs tomorrow need not be the one that was audited today; a compromised or rug-pulled release rides in on exactly that mutability. The gate blocks an added line that references an action by a non-SHA ref (owner/repo at a tag/branch); a full 40-char SHA pin passes, local actions (no ref) pass, and 'pragma: allowlist unpinned-action' on the same line is a visible, deliberate exception. This is the OpenSSF Scorecard Pinned-Dependencies control for the slice a diff can show; signature and provenance verification stay out of scope.

- Skill: `open-coder-ai/pin-github-actions` (Agent Skill)
- Install (CLI): `npx skillmds@latest add open-coder-ai/pin-github-actions`
- Raw SKILL.md: https://api.skillmd.com/api/skills/open-coder-ai/pin-github-actions/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: open-coder-ai (https://skillmd.com/u/open-coder-ai)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/open-coder-ai/pin-github-actions

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# Pin GitHub Actions

The mechanizable slice of CI supply-chain hardening, enforced at two points: at commit (the git hook, over staged changes) and at agent tool-use (over a tool call's arguments, as the agent writes) -- a workflow that references a third-party GitHub Action by a movable ref -- a branch or a version tag -- instead of a full 40-character commit SHA. A tag like v4 or a branch like main can be re-pointed at new code after review, so the action that runs tomorrow need not be the one that was audited today; a compromised or rug-pulled release rides in on exactly that mutability. The gate blocks an added line that references an action by a non-SHA ref (owner/repo at a tag/branch); a full 40-char SHA pin passes, local actions (no ref) pass, and 'pragma: allowlist unpinned-action' on the same line is a visible, deliberate exception. This is the OpenSSF Scorecard Pinned-Dependencies control for the slice a diff can show; signature and provenance verification stay out of scope.

```
on(commit|tool_use): block(content_regex) scan=added_lines allowlist_pragma=pragma:\s*allowlist\s+unpinned-action ...
Unpinned GitHub Action detected: a workflow references an action by a tag or branch (owner/repo at a movable ref) rather than a full 40-character commit SHA. Pin it to the SHA -- keep the version in a trailing comment for readability -- so a re-tagged or compromised release cannot change what runs. At commit, 'pragma: allowlist unpinned-action' on the same line marks a deliberate exception; the pragma is NOT honored at tool-use, where the scanned text is a live tool argument an appended token could neutralize.
```

This skill is advisory: the client reading it has no mechanism to enforce it. The same policy compiled by `chock` becomes a git hook that exits non-zero. See https://github.com/open-coder-ai/chock