feat(nix): migrate to flake-parts modular architecture

[ahmedelgabri]

Complete Migration to Flake-Parts with Dendritic Pattern

This PR completes the migration of the entire Nix configuration to flake-parts following the Dendritic Pattern architecture.

🎯 Summary

The configuration now follows a modular, aspect-oriented architecture where:

• Every file is a flake-parts module (auto-discovered via import-tree)
• Features are organized by purpose, not by platform
• Hosts import features via inputs.self.modules.*
• Single source of truth for each feature across all systems

📊 Changes Overview

Modules Migrated (26 Feature Modules)

Shared modules (21) - work on both darwin and nixos:

• Core: git, vim, tmux, ssh, gpg, user-shell
• Terminal: kitty, ghostty, yazi, bat, ripgrep
• Development: node, python, go, rust
• Applications: gui, mail, discord, ai, zk, mpv, yt-dlp
• Utilities: misc, agenix

Darwin-only modules (2):

• hammerspoon, karabiner

System modules (7):

• user-options, nix-daemon, state-version, home-manager-integration, fonts, darwin-defaults, feature-defaults

Architecture Improvements

Before:

nix/modules/
├── shared/          # 23 modules + default.nix
└── darwin/          # 2 modules + default.nix

After:

nix/
├── features/        # 26 feature modules
├── system/          # 7 system modules
└── hosts/           # 4 host configs (single file each)

✨ Key Benefits

1. ✅ Aspect-Oriented Organization - Organize by feature (git, vim), not platform (darwin, nixos)
2. ✅ Auto-Discovery - All modules discovered via import-tree
3. ✅ Single File Per Feature - Each feature is self-contained
4. ✅ Single File Per Host - No more configuration.nix + flake-parts.nix split
5. ✅ No specialArgs Anti-Pattern - Access modules via inputs.self.modules.*
6. ✅ Sensible Defaults - feature-defaults module enables common features
7. ✅ Easy Overrides - Hosts can override with lib.mkDefault
8. ✅ Cross-Platform - Single module works on both darwin and nixos

🏗️ Architecture

Feature Modules

Every feature module follows this pattern:

# nix/features/git.nix
{inputs, ...}: let
  gitModule = {pkgs, lib, config, ...}: let
    cfg = config.my.modules.git;
  in {
    options.my.modules.git.enable = lib.mkEnableOption "git module";
    config = lib.mkIf cfg.enable {
      # Git configuration here
    };
  };
in {
  flake.modules.darwin.git = gitModule;
  flake.modules.nixos.git = gitModule;
}

Host Configuration

Hosts import system and feature modules:

# nix/hosts/alcantara.nix
{inputs, ...}: {
  flake.modules.darwin.alcantara = {config, pkgs, ...}: {
    imports = with inputs.self.modules.darwin; [
      user-options
      nix-daemon
      state-version
      home-manager-integration
      fonts
      defaults
      feature-defaults  # Enables most features by default
    ];

    # Override or enable opt-in features
    my.modules = {
      mail.enable = true;
      gpg.enable = true;
      discord.enable = true;
    };
  };
}

Auto-Discovery

All modules are auto-discovered via import-tree:

# flake.nix
inputs.import-tree.url = "github:vic/import-tree";

outputs = inputs @ {flake-parts, import-tree, ...}:
  flake-parts.lib.mkFlake {inherit inputs;} {
    systems = ["x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin"];
    imports = [(import-tree ./nix)];  # Auto-discover all modules!
  };

📝 Migration Details

What Changed

1. Removed:

   • nix/modules/shared/ (23 modules + default.nix)
   • nix/modules/darwin/ (2 modules + default.nix)
   • nix/programs/ (example directory)

2. Added:

   • nix/features/ (26 feature modules in flake-parts format)
   • nix/system/feature-defaults.nix (replaces old default.nix)

3. Migrated:

   • All feature modules to flake.modules.{darwin,nixos}.<name> pattern
   • All hosts to single-file configuration
   • Fixed relative paths (../../../config/ → ../../config/)
   • Fixed broken host imports (pandoras-box, rocket, nixos)

Commits

1. refactor(nix): use import-tree and migrate to nix/ directory
2. refactor(nix): cleanup and break down modules into focused aspects
3. fix(nix): properly migrate pandoras-box and rocket host configs
4. feat(nix): complete migration to flake-parts with Dendritic Pattern
5. docs(nix): update migration documentation

⚠️ Testing Required

Before merging, please test:

# Check flake validity
nix flake check

# Test build for each host
nix build .#darwinConfigurations.alcantara.system --dry-run
nix build .#darwinConfigurations.pandoras-box.system --dry-run
nix build .#darwinConfigurations.rocket.system --dry-run
nix build .#nixosConfigurations.nixos.config.system.build.toplevel --dry-run

# Test evaluation
nix eval .#darwinConfigurations.alcantara.config.system.build.toplevel

# Test actual activation (on a test system first!)
darwin-rebuild switch --flake .#alcantara

Known Testing Gaps:

• ⚠️ This PR was created without access to nix command for testing
• ⚠️ Changes need to be validated in a real Nix environment
• ⚠️ Relative paths (../../config/) need verification
• ⚠️ Activation scripts need testing
• ⚠️ Home-manager integration needs verification

📚 Documentation

See DENDRITIC-MIGRATION.md for:

• Complete architecture overview
• How to add new features
• Benefits and rationale
• Usage examples
• Resources

🔄 Migration Path

Adding New Features

1. Create a feature module in nix/features/:

# nix/features/example.nix
{inputs, ...}: let
  exampleModule = {pkgs, lib, config, ...}: let
    cfg = config.my.modules.example;
  in {
    options.my.modules.example.enable = lib.mkEnableOption "example";
    config = lib.mkIf cfg.enable {
      # Your config here
    };
  };
in {
  flake.modules.darwin.example = exampleModule;
  flake.modules.nixos.example = exampleModule;
}

2. Optionally add to nix/system/feature-defaults.nix
3. Enable in hosts as needed

Disabling Features

Hosts can disable features enabled by default:

my.modules = {
  discord.enable = lib.mkForce false;  # Disable completely
  # OR
  discord.enable = false;              # If not using mkDefault
};

🔗 Resources

• Dendritic Pattern
• flake-parts Documentation
• import-tree
• Dendritic Design Guide

🎉 Result

The configuration now has:

• ✅ Clean separation of concerns (features, system, hosts)
• ✅ Auto-discovery of all modules
• ✅ Aspect-oriented organization
• ✅ Feature-based architecture
• ✅ Single file per host and feature
• ✅ No specialArgs anti-pattern
• ✅ Cross-platform compatibility

This migration sets a solid foundation for future improvements and makes the configuration more maintainable and understandable.

[ahmedelgabri]

@claude

[ahmedelgabri]

@claude

[ahmedelgabri]

@claude

[claude]

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