nix-packaging

name	nix-packaging
description	Use this when writing or modifying Nix package definitions and related repo exports in this NUR repository.

Use this when

• Creating a new package under pkgs/
• Updating an exported package version or hash
• Fixing a build/runtime issue in an existing derivation
• Adding or updating a library helper in lib/
• Wiring exports through default.nix or lib/default.nix

Repository-specific ground rules

• default.nix is the source of truth for exported packages.
• lib/default.nix is the source of truth for library helpers and currently exports fetchPixiv.
• modules/default.nix and overlays/default.nix are placeholders right now; do not document them as populated unless you add real entries.
• CI behavior comes from ci.nix, not from guesswork.

Packaging styles actually used in this repo

Python applications and packages

Used heavily for GUI apps and helpers.

Examples:

• pkgs/JMComic-qt.nix
• pkgs/picacg-qt.nix
• pkgs/sr-vulkan.nix

Common patterns:

• python3Packages.buildPythonApplication
• python3Packages.buildPythonPackage
• wrapper scripts for GUI entrypoints
• Vulkan or site-packages symlink setup in postInstall

Flutter applications

Example: pkgs/LoveIwara/default.nix

Use the pinned Flutter SDK's buildFlutterApplication (currently flutter347) for reproducible Linux desktop builds:

• convert and check in upstream pubspec.lock as pubspec.lock.json
• use customSourceBuilders when Dart native-asset hooks attempt sandboxed downloads
• put dynamically loaded FFI libraries in runtimeDependencies
• install the upstream desktop entry and icon in postInstall
• launch the built GUI to verify native plugins and runtime libraries

Rust packages

Example: pkgs/waybar-vd/default.nix

rustPlatform.buildRustPackage rec {
  pname = "...";
  version = "...";

  cargoLock.lockFile = ./Cargo.lock;
  postPatch = ''
    ln -s ${./Cargo.lock} Cargo.lock
  '';
}

Go packages

Example: pkgs/mihomo-smart.nix

buildGoModule rec {
  pname = "...";
  version = "...";
  vendorHash = "sha256-...";
}

npm packages

Example: pkgs/wechatbot-mcp.nix

buildNpmPackage rec {
  pname = "...";
  version = "...";
  npmDepsHash = "sha256-...";
  npmBuildScript = "build";
}

bun + stdenvNoCC packages

Example: pkgs/mcp-cli.nix

This repo also contains packages that:

• prebuild dependency trees as fixed-output derivations
• use bun install --frozen-lockfile
• compile a final CLI binary with bun build --compile

Generic derivations

Examples:

• pkgs/grub-theme-yorha.nix

Use stdenv.mkDerivation or stdenvNoCC.mkDerivation for asset packages, extracted binaries, or custom build workflows.

Export wiring patterns

Package export in default.nix

some-package = pkgs.callPackage ./pkgs/some-package.nix { };

Library export in lib/default.nix

{ pkgs }:
{
  someHelper = pkgs.callPackage ./someHelper/default.nix { };
}

Current repo-specific examples worth imitating

• JMComic-qt / picacg-qt: Python GUI packaging plus runtime wrapping
• LoveIwara: source-built Flutter GUI with offline pub dependencies, system SQLite, libmpv runtime wrapping, and upstream desktop integration
• sr-vulkan: model composition through sr-vulkan-models
• deskbrid: Rust package whose compositor helper tools stay on PATH at runtime — no wrapper
• fetchPixiv: helper-style library export using fetchurl fallback URLs

Hash techniques

Build once with a fake hash

hash = lib.fakeHash;

Then rebuild and copy the real hash from the failure output.

Prefetch helpers

nix-prefetch-url --unpack <url>
nix-prefetch-github owner repo --rev v1.0.0

Checklist

• Export wiring updated in default.nix or lib/default.nix if needed
• Runtime behavior checked for wrapped GUI / CLI tools
• Docs updated if package inventory or repo behavior changed