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 bolivian-peru/os-moda --skill nix-optimizergit clone --depth 1 https://github.com/bolivian-peru/os-modaWrote 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/bolivian-peru/os-moda/nix-optimizer)<a href="https://agentmods.dev/skills/bolivian-peru/os-moda/nix-optimizer"><img src="https://agentmods.dev/badge/skills/bolivian-peru/os-moda/nix-optimizer/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/bolivian-peru/os-moda/nix-optimizer"><img src="https://agentmods.dev/badge/skills/bolivian-peru/os-moda/nix-optimizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00028 | $0.00499 |
| Opus 5 | $0.00014 | $0.00249 |
| Sonnet 5 | $0.00006 | $0.00100 |
| Haiku 4.5 | $0.00003 | $0.00050 |
Grade A, and why
nix-optimizer 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.
What it actually says
Nix Store Optimizer
Intelligent garbage collection and store management.
Store Analysis
shell_exec({ command: "du -sh /nix/store 2>/dev/null" })
shell_exec({ command: "nix-store --gc --print-dead 2>/dev/null | wc -l" })
shell_exec({ command: "nixos-rebuild list-generations 2>/dev/null | tail -20" })
Smart GC Strategy
Don't just nix-collect-garbage -d. Be intelligent:
- Always keep: current generation, last known-good, backup baseline
- Analyze: which generations introduced large store additions
- Recommend: targeted cleanup with estimated space recovery
Nix Store Report:
Store size: 28.4 GB across 47 generations
Recommended to keep:
Gen 50 (current) — 12.1 GB active
Gen 47 (pre-OpenSSL update) — rollback point
Gen 42 (last backup baseline)
Safe to remove: 44 generations → reclaims ~19 GB
Large items:
/nix/store/...-linux-6.6.12 (old kernel) — 980 MB
/nix/store/...-chromium-121 (old browser) — 1.4 GB
/nix/store/...-texlive-2023 (unused) — 2.1 GB
Proceed with smart cleanup?
Execution
shell_exec({ command: "nix-collect-garbage --delete-older-than 14d" })
shell_exec({ command: "nix-store --optimise" }) # dedup hardlinks
Post-Cleanup
memory_store({
summary: "Nix GC: freed 19GB, kept gens 42,47,50",
detail: "Store reduced from 28.4GB to 9.3GB. 44 generations removed.",
category: "system.config",
tags: "nix,garbage-collection,optimization"
})
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.
- 10d ago First seen · 70 lines · 28 tokens per session scan A 7ff7d6ccd683
nix-optimizer is a skill published in the GitHub repository bolivian-peru/os-moda (117 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 28 tokens to every session and 499 once invoked, about $0.0001 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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