Borrowing it
Nothing to install: this file belongs to joshsymonds/nix-config. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/joshsymonds/nix-config/main/CLAUDE.mdgit clone --depth 1 https://github.com/joshsymonds/nix-configWrote 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/instructions/joshsymonds/nix-config/claude-md)<a href="https://agentmods.dev/instructions/joshsymonds/nix-config/claude-md"><img src="https://agentmods.dev/badge/instructions/joshsymonds/nix-config/claude-md.svg" alt="Measured on agentmods" 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 | $0.01132 | $0.01132 |
| Opus 5 | $0.00566 | $0.00566 |
| Sonnet 5 | $0.00226 | $0.00226 |
| Haiku 4.5 | $0.00113 | $0.00113 |
Grade B, and why
nix-config CLAUDE.md scanned grade B with 1 finding 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 8d 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.
Asks for rootmediumPrivilege escalation
A mod that escalates privileges can change anything on the machine, not only the project.
`update` is a `writeShellScriptBin` on `PATH` (per host: `nh os switch` for NixOS, `nh darwin switch` for macOS, ssh-into-ultraviolet for bluedesert). It works from non-interactive shells, agents, and subprocesses — no n How it starts
The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.
nix-config
Flake-based Nix configuration managing multiple systems.
Systems
| Host | Platform | Description |
|---|---|---|
| gnomon | NixOS (x86_64-linux) | Primary dev machine now, niri + DankMaterialShell, gaming rig |
| ultraviolet | NixOS (x86_64-linux) | Main homelab server |
| bluedesert | NixOS (x86_64-linux) | Z-Wave bridge (zwave-js-ui) |
| vermissian | NixOS (x86_64-linux) | Work/dev server |
| echelon | NixOS (x86_64-linux) | Remote tailnet node |
| stygianlibrary | NixOS (x86_64-linux) | halmasuit test rig, hardware-identical to gnomon |
| ninuan | macOS (aarch64-darwin) | Aerospace WM; rarely powered on now that gnomon is primary |
| shrike | Nix-on-Droid (aarch64-linux) | Pixel 11: terminal userland via nix-on-droid; Android app set declared in hosts/shrike/apps.nix, converged by on-phone update |
| testhost | NixOS (x86_64-linux) | VM fixture for the installer test, not a real machine |
| installer | NixOS (x86_64-linux) | Generic installer ISO output, not a deployed host |
Essential Commands
update # Rebuild current system (real binary, not an alias)
nix flake check # Validate flake
nix build .#<package> # Build a package
IMPORTANT: Run update after any Nix config changes. Nothing takes effect until rebuilt.
update is a writeShellScriptBin on PATH (per host: nh os switch for NixOS, nh darwin switch for macOS, ssh-into-ultraviolet for bluedesert). It works from non-interactive shells, agents, and subprocesses — no need to fall back to invoking nh directly. It pre-flights sudo -n true and refuses with a clear error if sudo would prompt, so agents fail fast instead of hanging.
Git gotcha: Nix flakes only see git-tracked files. Run git add before nix flake check.
Directory Structure
flake.nix # Entry point
hosts/ # System configs (per-machine)
home-manager/ # User configs (apps, dotfiles)
claude-code/ # Claude Code agents, hooks, settings
pkgs/ # Custom packages
overlays/ # Nixpkgs modifications
home-assistant/ # HA dashboards and config
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.
- 8d ago First seen · 88 lines · 1,132 tokens per session scan B 48b61f357a29
nix-config CLAUDE.md is an instructions file published in the GitHub repository joshsymonds/nix-config (835 stars, last pushed today), licensed MIT. It adds 1,132 tokens to every session, about $0.0057 per session on Opus 5. A static security scan graded it B with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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