nix-best-practices

Nix patterns for flakes, overlays, unfree handling, and binary overlays. Use when working with flake.nix or shell.nix.

1.59x

Quality

84%

Does it follow best practices?

Impact

91%

1.59x

Average score across 3 eval scenarios

Securityby

Passed

No known issues

Evaluation results

100%

18%

Set Up a Reproducible Development Environment with External Overlays

Flake structure, follows pattern, overlays, dev shell

Criteria

Without context

With context

nixpkgs URL

100%

flake-utils input

100%

eachDefaultSystem

100%

devShells.default

100%

follows on overlay

100%

All inputs in outputs

100%

overlays.default pattern

100%

C_INCLUDE_PATH export

100%

LIBRARY_PATH export

100%

PKG_CONFIG_PATH export

100%

direnv .envrc

100%

Without context: $0.1911 · 45s · 14 turns · 20 in / 2,460 out tokens

With context: $0.2215 · 45s · 13 turns · 15 in / 2,559 out tokens

98%

78%

Add a Commercial Code Analysis Tool to a Team's Dev Environment

Unfree packages with nixpkgs-unfree

Criteria

Without context

With context

nixpkgs-unfree input URL

100%

nixpkgs-unfree follows nixpkgs

100%

pkgs imported from nixpkgs-unfree

100%

No config.allowUnfree in flake

100%

notes.md allowUnfree limitation

50%

100%

notes.md correct alternative

100%

eachDefaultSystem used

62%

100%

All inputs in outputs

100%

Unfree direnv comment or .envrc

66%

Without context: $0.7392 · 4m 11s · 19 turns · 26 in / 15,601 out tokens

With context: $0.3320 · 1m 7s · 21 turns · 25 in / 3,529 out tokens

76%

Package the Official Buildkite Agent Binary as a Nix Overlay

Binary overlay creation

Criteria

Without context

With context

stdenv.mkDerivation used

100%

fetchurl used

100%

dontUnpack = true

sourceRoot = "."

All four platforms

100%

Unsupported system error

62%

100%

packages.default output

100%

Named package output

100%

System-scoped overlays.default

Top-level overlays.default

80%

100%

README nix-prefetch-url command

100%

README SRI conversion command

100%

Without context: $0.2465 · 1m 2s · 13 turns · 15 in / 3,984 out tokens

With context: $0.3039 · 1m 5s · 16 turns · 54 in / 4,162 out tokens

Repository: NeverSight/skills_feed
Commit: 5342bca

Evaluated: 13 days ago
Agent: Claude Code
Model: Claude Sonnet 4.6

Table of Contents

Set Up a Reproducible Development Environment with External Overlays Add a Commercial Code Analysis Tool to a Team's Dev Environment Package the Official Buildkite Agent Binary as a Nix Overlay

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