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.
npx skills add shikanime-labs/skills --skill nixpkgs-pr-reviewgit clone --depth 1 https://github.com/shikanime-labs/skillsWrote 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.
[](https://agentmods.dev/skills/shikanime-labs/skills/nixpkgs-pr-review)<a href="https://agentmods.dev/skills/shikanime-labs/skills/nixpkgs-pr-review"><img src="https://agentmods.dev/badge/skills/shikanime-labs/skills/nixpkgs-pr-review/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.
<a href="https://agentmods.dev/skills/shikanime-labs/skills/nixpkgs-pr-review"><img src="https://agentmods.dev/badge/skills/shikanime-labs/skills/nixpkgs-pr-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00041 | $0.02204 |
| Opus 5.5 | $0.00016 | $0.00882 |
| Sonnet 5.5 | $0.00008 | $0.00441 |
| Haiku 4.5 | $0.00004 | $0.00220 |
Grade A, and why
nixpkgs-pr-review 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 7d 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.
How it starts
The opening of the file, as written. The whole thing — 191 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Nixpkgs PR Review
Review upstream NixOS/nixpkgs pull requests
through the official contribution process: build every package the PR changes
with nixpkgs-review, then check the diff against nixpkgs conventions before
deciding on approval. Reports only — never auto-approve or merge without the
maintainer's go-ahead.
This skill is grounded in a real modernization PR,
NixOS/nixpkgs#557075
(ghstack: modernize), used below as the running example.
When to Use
- "review this nixpkgs PR", "check PR #N on NixOS/nixpkgs", "is this package update good to merge"
- Requested as a reviewer on an upstream nixpkgs PR
- Any PR touching
pkgs/,pkgs/by-name/,nixos/modules/,lib/,pkgs/test/, ornixos/tests/in nixpkgs
Prerequisites
- A full (non-shallow) local nixpkgs clone. Shallow clones miss merge bases and
nixpkgs-reviewfails on them:git clone https://github.com/NixOS/nixpkgs(add--depthis NOT supported). nixavailable (Lix or Nix ≥ 2.18).nixpkgs-reviewis packaged:nix run 'nixpkgs#nixpkgs-review' -- ...ornix shell nixpkgs#nixpkgs-review.ghauthenticated if posting the result as a PR comment.- Optional but recommended:
nom(nix-output-monitor) for readable build logs;glowanddeltafor rendered markdown/diffs. Skipped silently if absent.
Quick Reference
cd ~/git/nixpkgs
nixpkgs-review pr <PR#> # build changed packages, drop into shell
nixpkgs-review pr <PR#> --post-result # build + post markdown result to the PR
nixpkgs-review pr <PR#> --print-result --no-shell
nixpkgs-review pr <PR#> --systems aarch64-linux
nixpkgs-review pr <PR#> --run 'cat report.json'
nixpkgs-review pr <PR#> --no-shell --post-result
nixpkgs-review rev HEAD # review a local commit/branch
nixpkgs-review wip # review uncommitted working-tree changes
nixpkgs-review pr <PR#> --extra-nixpkgs-config '{ cudaSupport = true; }'
What ships with it
2 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.
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.
- 7d ago Changed 6b29b11770d0
- 17d ago Changed · +1 lines 16cee0f68523
- 19d ago Changed · +3 lines 35ba210e4663
- 26d ago First seen · 187 lines · 41 tokens per session scan A 1655b360c099
nixpkgs-pr-review is a skill published in the GitHub repository shikanime-labs/skills (2 stars, last pushed today), licensed Apache-2.0. It adds 41 tokens to every session and 2,204 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-09-23.
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