system-packages

system-packages is a skill for Claude Code, Codex from bolivian-peru/os-moda. It costs 40 tokens per session (392 once invoked), scanned A, original, Apache-2.0.

A helper for managing software packages on NixOS, a Linux system configured from text files. Package changes are recorded in the system configuration and can be rolled back.

In plain words
What is it for?
Use it to search for, install, remove, list, and roll back system packages through NixOS configuration changes.
Why use it?
It avoids one-off installations that make a NixOS machine difficult to reproduce or undo.

Skill for Claude CodeCodex

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

Good fit Use it to search for, install, remove, list, and roll back system packages through NixOS configuration changes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/bolivian-peru/os-moda/system-packages
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 bolivian-peru/os-moda --skill system-packages
Clone the repo
git clone --depth 1 https://github.com/bolivian-peru/os-moda

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 system-packages

README.md
[![agentmods](https://agentmods.dev/badge/skills/bolivian-peru/os-moda/system-packages/github.svg)](https://agentmods.dev/skills/bolivian-peru/os-moda/system-packages)
Your own site
<a href="https://agentmods.dev/skills/bolivian-peru/os-moda/system-packages"><img src="https://agentmods.dev/badge/skills/bolivian-peru/os-moda/system-packages/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 system-packages

Your own site · 80×15
<a href="https://agentmods.dev/skills/bolivian-peru/os-moda/system-packages"><img src="https://agentmods.dev/badge/skills/bolivian-peru/os-moda/system-packages.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 392 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
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 $0.00040 $0.00392
Opus 5 $0.00020 $0.00196
Sonnet 5 $0.00008 $0.00078
Haiku 4.5 $0.00004 $0.00039

Measured 10d ago against content hash 8098adff9941, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

system-packages 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 10d 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/system-packages/SKILL.md · 55 lines

What it actually says

System Packages Skill

You manage packages through NixOS's declarative model. Every package change edits configuration.nix and triggers a rebuild. This means every change is atomic, reproducible, and rollbackable.

Search Packages

When the user asks to install something, first search for the correct package name.

Install Packages

  1. Edit /etc/nixos/configuration.nix to add the package to environment.systemPackages
  2. Validate with a dry-run rebuild
  3. Show the user what will change
  4. On approval, rebuild with nixos-rebuild switch
  5. Log the installation to memory

Always use declarative NixOS config. Never suggest nix-env -i — it breaks the declarative model.

Remove Packages

  1. Remove from environment.systemPackages in configuration.nix
  2. Rebuild
  3. Optionally garbage collect old generations

Rollback

NixOS keeps every generation. To rollback:

  • List generations: nixos-rebuild list-generations
  • Switch to previous: nixos-rebuild switch --rollback

Remember

After every package operation, store what happened:

memory_store({
  summary: "Installed postgresql-16",
  detail: "Added services.postgresql.enable = true and services.postgresql.package = pkgs.postgresql_16 to configuration.nix. Rebuild generation 45.",
  category: "system.package",
  tags: ["postgresql", "install", "generation-45"]
})
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. 10d ago First seen · 55 lines · 40 tokens per session scan A 8098adff9941

Subscribe to this mod's changes

system-packages is a skill published in the GitHub repository bolivian-peru/os-moda (117 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 40 tokens to every session and 392 once invoked, about $0.0002 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 2026-08-30.

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