Clean up Nix configuration and remove old files

- Move Nix package and module to nix/ directory for better organization
- Remove old Nix files (systant.nix, systant-old.nix, etc.)
- Remove debug script and systemd service file
- Update config files for new Nix structure
- Add CLAUDE.md with project documentation

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -21,3 +21,10 @@ system_stats_daemon-*.tar
 
 # Temporary files, for example, from tests.
 /tmp/
+
+# Nix direnv cache and generated files
+.direnv/
+
+# Nix result symlinks
+result
+result-*

CLAUDE.md

@@ -0,0 +1,79 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Common Commands
+
+### Development
+```bash
+# Install dependencies
+mix deps.get
+
+# Compile the project
+mix compile
+
+# Run in development (non-halt mode)
+mix run --no-halt
+
+# Run tests
+mix test
+
+# Run specific test
+mix test test/systant_test.exs
+
+# Enter development shell (via Nix)
+nix develop
+```
+
+### Production
+```bash
+# Build production release
+MIX_ENV=prod mix release
+
+# Run production release
+_build/prod/rel/systant/bin/systant start
+```
+
+## Architecture Overview
+
+This is an Elixir OTP application that serves as a systemd daemon for MQTT-based system monitoring, designed for deployment across multiple NixOS hosts to integrate with Home Assistant.
+
+### Core Components
+- **Systant.Application** (`lib/systant/application.ex`): OTP application supervisor that starts the MQTT client
+- **Systant.MqttClient** (`lib/systant/mqtt_client.ex`): GenServer that handles MQTT connection, publishes stats every 30 seconds, and listens for commands
+- **Configuration**: MQTT settings configurable via environment variables or config files
+
+### Key Libraries
+- **Tortoise**: MQTT client library for pub/sub functionality
+- **Jason**: JSON encoding/decoding for message payloads
+
+### MQTT Behavior
+- Publishes "Hello from systant" messages with timestamp and hostname to stats topic every 30 seconds
+- Subscribes to commands topic for incoming events that can trigger user-customizable actions
+- Uses randomized client ID to avoid conflicts across multiple hosts
+- Sends immediate hello message on startup
+
+### Default Configuration
+- **MQTT Host**: `mqtt.home` (not localhost)
+- **Stats Topic**: `systant/${hostname}/stats` (per-host topics)
+- **Command Topic**: `systant/${hostname}/commands` (per-host topics)
+- **Publish Interval**: 30 seconds
+
+### NixOS Deployment
+This project includes a complete Nix packaging and NixOS module:
+
+- **Package**: `nix/package.nix` - Builds the Elixir release using beamPackages.mixRelease
+- **Module**: `nix/nixos-module.nix` - Provides `services.systant` configuration options
+- **Development**: Use `nix develop` for development shell with Elixir/Erlang
+
+The NixOS module supports:
+- Configurable MQTT connection settings
+- Per-host topic naming using `${config.networking.hostName}`
+- Environment variable configuration for runtime settings
+- Systemd service with security hardening
+- Auto-restart and logging to systemd journal
+
+### Future Plans
+- Integration with Home Assistant via custom MQTT integration
+- Expandable command handling for host-specific automation
+- Multi-host deployment for comprehensive system monitoring

config/config.exs

@@ -1,15 +1,5 @@
 import Config
 
-config :systant, Systant.MqttClient,
-  host: "mqtt.home",
-  port: 1883,
-  client_id: "systant",
-  username: "mqtt",
-  password: "pleasework",
-  stats_topic_base: "systant",  # Will become systant/{hostname}/stats
-  command_topic_base: "systant", # Will become systant/{hostname}/commands
-  publish_interval: 30_000
-
 config :logger, :console,
   format: "$time $metadata[$level] $message\n",
   metadata: [:request_id]

config/runtime.exs

@@ -8,11 +8,11 @@ end
 
 # Runtime configuration that can use environment variables
 config :systant, Systant.MqttClient,
-  host: System.get_env("SYSTANT_MQTT_HOST", "localhost"),
+  host: System.get_env("SYSTANT_MQTT_HOST", "mqtt.home"),
   port: String.to_integer(System.get_env("SYSTANT_MQTT_PORT", "1883")),
   client_id: System.get_env("SYSTANT_CLIENT_ID", "systant"),
   username: System.get_env("SYSTANT_MQTT_USERNAME"),
   password: System.get_env("SYSTANT_MQTT_PASSWORD"),
   stats_topic: System.get_env("SYSTANT_STATS_TOPIC", "systant/#{hostname}/stats"),
   command_topic: System.get_env("SYSTANT_COMMAND_TOPIC", "systant/#{hostname}/commands"),
-  publish_interval: String.to_integer(System.get_env("SYSTANT_PUBLISH_INTERVAL", "30000"))
+  publish_interval: String.to_integer(System.get_env("SYSTANT_PUBLISH_INTERVAL", "30000"))

debug-nix-store.sh

@@ -1,39 +0,0 @@
-#!/bin/bash
-# Debug script to check what's in the Nix store
-STORE_PATH="/nix/store/i3fa1p0y8mcyljzfsj6k65qfpmd4yyaf-systant-0.1.0"
-
-echo "=== Checking Nix store contents ==="
-echo "Store path: $STORE_PATH"
-echo
-
-echo "=== Top level contents ==="
-ls -la "$STORE_PATH/"
-echo
-
-echo "=== Looking for COOKIE files ==="
-find "$STORE_PATH" -name "*COOKIE*" -o -name "*cookie*" 2>/dev/null || echo "No COOKIE files found"
-echo
-
-echo "=== releases directory ==="
-if [ -d "$STORE_PATH/releases" ]; then
-    ls -la "$STORE_PATH/releases/"
-else
-    echo "No releases directory found"
-fi
-echo
-
-echo "=== bin directory ==="
-if [ -d "$STORE_PATH/bin" ]; then
-    ls -la "$STORE_PATH/bin/"
-else
-    echo "No bin directory found"
-fi
-echo
-
-echo "=== Checking startup script ==="
-if [ -f "$STORE_PATH/bin/systant" ]; then
-    echo "Startup script exists, checking for COOKIE references:"
-    grep -n "COOKIE" "$STORE_PATH/bin/systant" || echo "No COOKIE references in startup script"
-else
-    echo "No startup script found"
-fi

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1753939845,
+        "narHash": "sha256-K2ViRJfdVGE8tpJejs8Qpvvejks1+A4GQej/lBk5y7I=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "94def634a20494ee057c76998843c015909d6311",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -6,16 +6,34 @@
     flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs =
-    flake-utils.lib.eachDefaultSystem (system:
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
       let
-        pkgs = nixpkgs.legacyPackages.${system};
+        pkgs = import nixpkgs {
+          system = system;
+          config.allowUnfree = true;
+        };
       in
       {
         devShells.default = pkgs.mkShell {
           buildInputs = with pkgs; [
             elixir
             erlang
+            claude-code
+            aider-chat
+            nodejs_20
+            yarn
+            deno
+            python311
+            python311Packages.pip
+            python311Packages.ipython
+
           ];
 
           shellHook = ''
@@ -23,5 +41,6 @@
             elixir --version
           '';
         };
-      });
+      }
-}
+    );
+}

systant-manual.nix

@@ -1,62 +0,0 @@
-{ lib, stdenv, fetchgit, elixir, erlang, rebar3, git }:
-
-stdenv.mkDerivation rec {
-  pname = "systant";
-  version = "0.1.0";
-
-  src = fetchgit {
-    url = "https://git.ryanpandya.com/ryan/systant.git";
-    rev = "f8173a1afb03623039ff504c587d7322a9876f3d";
-    sha256 = "sha256-1cRfSoH+JdO4a7q4hRZSkoDMk2wMCYRIyCIN56FSUgg=";
-  };
-
-  nativeBuildInputs = [ elixir erlang rebar3 git ];
-
-  # Disable network access - we'll handle deps manually
-  MIX_ENV = "prod";
-  
-  configurePhase = ''
-    export MIX_HOME=$TMPDIR/mix
-    export HEX_HOME=$TMPDIR/hex
-    export REBAR_CACHE_DIR=$TMPDIR/rebar3
-    
-    # Install hex and rebar locally
-    mix local.hex --force
-    mix local.rebar --force
-  '';
-
-  buildPhase = ''
-    # This will fail but that's OK - we're using it to get deps info
-    mix deps.get || true
-    
-    # Manual dependency installation (you'd need to add each dep here)
-    # For now, let's try without deps to see if it builds
-    mix deps.compile --skip-deps || true
-    mix compile
-    mix release
-    
-    echo "=== Build phase debug ==="
-    find _build/prod/rel/ -name "*COOKIE*" || echo "No COOKIE in build"
-  '';
-
-  installPhase = ''
-    mkdir -p $out
-    cp -r _build/prod/rel/systant/* $out/
-    
-    # Force create COOKIE file
-    mkdir -p $out/releases
-    echo "systant-cookie-change-in-production" > $out/releases/COOKIE
-    
-    echo "=== Install phase debug ==="
-    echo "COOKIE created manually in installPhase" > /tmp/manual-nix-debug
-    ls -la $out/releases/
-    cat $out/releases/COOKIE
-  '';
-
-  meta = with lib; {
-    description = "Systant - System stats MQTT daemon";
-    homepage = "https://git.ryanpandya.com/ryan/systant";
-    license = licenses.mit;
-    platforms = platforms.linux;
-  };
-}

systant-old.nix

@@ -1,73 +0,0 @@
-{ lib
-, stdenv
-, fetchgit
-, elixir
-, erlang
-, rebar3
-, git
-, cacert
-, glibcLocales
-}:
-
-stdenv.mkDerivation rec {
-  pname = "systant";
-  version = "0.1.0";
-
-  src = fetchgit {
-    url = "https://git.ryanpandya.com/ryan/systant.git";
-    rev = "92fc90e3b470dd2d11ba3a84745e33195e8e9db3";
-    sha256 = lib.fakeSha256; # Replace with actual hash after first build attempt
-  };
-
-  nativeBuildInputs = [
-    elixir
-    erlang
-    rebar3
-    git
-    cacert
-    glibcLocales
-  ];
-
-  buildPhase = ''
-    runHook preBuild
-    
-    # Set up environment for Mix/Hex
-    export MIX_ENV=prod
-    export MIX_HOME=$TMPDIR/mix
-    export HEX_HOME=$TMPDIR/hex
-    export REBAR_CACHE_DIR=$TMPDIR/rebar3
-    
-    # SSL and locale configuration
-    export SSL_CERT_FILE=${cacert}/etc/ssl/certs/ca-bundle.crt
-    export LOCALE_ARCHIVE=${glibcLocales}/lib/locale/locale-archive
-    export LC_ALL=en_US.UTF-8
-    export ELIXIR_ERL_OPTIONS="+fnu"
-    
-    # Install hex and rebar locally
-    mix local.hex --force
-    mix local.rebar --force
-    
-    # Get dependencies and build release
-    mix deps.get --only=prod
-    mix release
-    
-    runHook postBuild
-  '';
-
-  installPhase = ''
-    runHook preInstall
-    
-    mkdir -p $out
-    cp -r _build/prod/rel/systant/* $out/
-    
-    runHook postInstall
-  '';
-
-  meta = with lib; {
-    description = "Systant - System stats MQTT daemon for monitoring system metrics";
-    homepage = "https://git.ryanpandya.com/ryan/systant";
-    license = licenses.mit; # Update if different
-    maintainers = [ ]; # Add your maintainer info if desired
-    platforms = platforms.linux;
-  };
-}

systant-wrapper.nix

@@ -1,67 +0,0 @@
-{ lib, stdenv, fetchgit, elixir, erlang, rebar3, git, writeShellScript }:
-
-let
-  systantBase = stdenv.mkDerivation rec {
-    pname = "systant-base";
-    version = "0.1.0";
-
-    src = fetchgit {
-      url = "https://git.ryanpandya.com/ryan/systant.git";
-      rev = "f8173a1afb03623039ff504c587d7322a9876f3d";
-      sha256 = "sha256-1cRfSoH+JdO4a7q4hRZSkoDMk2wMCYRIyCIN56FSUgg=";
-    };
-
-    nativeBuildInputs = [ elixir erlang rebar3 git ];
-
-    MIX_ENV = "prod";
-    
-    configurePhase = ''
-      export MIX_HOME=$TMPDIR/mix
-      export HEX_HOME=$TMPDIR/hex
-      export REBAR_CACHE_DIR=$TMPDIR/rebar3
-      
-      mix local.hex --force
-      mix local.rebar --force
-    '';
-
-    buildPhase = ''
-      mix deps.get || true
-      mix deps.compile || true
-      mix compile
-      mix release
-    '';
-
-    installPhase = ''
-      mkdir -p $out
-      cp -r _build/prod/rel/systant/* $out/
-    '';
-  };
-
-  systantWrapper = writeShellScript "systant" ''
-    #!/bin/bash
-    export RELEASE_COOKIE="systant-cookie-change-in-production"
-    exec ${systantBase}/bin/systant "$@"
-  '';
-
-in stdenv.mkDerivation {
-  pname = "systant";
-  version = "0.1.0";
-  
-  buildCommand = ''
-    mkdir -p $out/bin
-    cp ${systantWrapper} $out/bin/systant
-    chmod +x $out/bin/systant
-    
-    # Copy the rest of the release
-    cp -r ${systantBase}/* $out/
-    
-    echo "Wrapper created - RELEASE_COOKIE will be set by wrapper script"
-  '';
-
-  meta = with lib; {
-    description = "Systant - System stats MQTT daemon";
-    homepage = "https://git.ryanpandya.com/ryan/systant";
-    license = licenses.mit;
-    platforms = platforms.linux;
-  };
-}

systant.service

@@ -1,26 +0,0 @@
-[Unit]
-Description=Systant MQTT Daemon
-After=network.target
-
-[Service]
-Type=exec
-User=root
-Group=root
-ExecStart=/opt/systant/bin/systant start
-ExecStop=/opt/systant/bin/systant stop
-Restart=always
-RestartSec=5
-StandardOutput=journal
-StandardError=journal
-SyslogIdentifier=systant
-WorkingDirectory=/opt/systant
-
-# Security settings - still apply restrictions where possible
-NoNewPrivileges=true
-PrivateTmp=true
-ProtectHome=true
-# Don't use ProtectSystem=strict since we need to read system stats
-ProtectSystem=false
-
-[Install]
-WantedBy=multi-user.target