feat(shells): add opencode dev shell with mkOpencodeRules demo

flake.nix

@@ -78,11 +78,11 @@
 
     # Development shells for various programming environments
     # Usage: nix develop .#<shell-name>
-    # Available shells: default, python, devops
+    # Available shells: default, python, devops, opencode
     devShells = forAllSystems (system: let
       pkgs = pkgsFor system;
     in
-      import ./shells {inherit pkgs;});
+      import ./shells {inherit pkgs inputs;});
 
     # Formatter for 'nix fmt'
     formatter = forAllSystems (system: (pkgsFor system).alejandra);

shells/default.nix

@@ -1,7 +1,10 @@
 # Development shells for various programming environments
 # Each shell can be accessed via: nix develop .#<shell-name>
 # Or used in home-manager/system configs
-{pkgs}: {
+{
+  pkgs,
+  inputs,
+}: {
   # Default shell for working on this repository
   default = pkgs.mkShell {
     name = "m3ta-nixpkgs-dev";
@@ -27,6 +30,7 @@
   };
 
   # Import all individual shell environments
-  python = import ./python.nix {inherit pkgs;};
+  python = import ./python.nix {inherit pkgs inputs;};
-  devops = import ./devops.nix {inherit pkgs;};
+  devops = import ./devops.nix {inherit pkgs inputs;};
+  opencode = import ./opencode.nix {inherit pkgs inputs;};
 }

shells/devops.nix

@@ -1,6 +1,9 @@
 # DevOps development environment
 # Usage: nix develop .#devops
-{pkgs}:
+{
+  pkgs,
+  inputs ? null,
+}:
 pkgs.mkShell {
   name = "devops-dev";
 

shells/opencode.nix

@@ -0,0 +1,155 @@
+# OpenCode development environment with AI coding rules
+# This shell demonstrates the mkOpencodeRules library provided by this repository
+# Usage: nix develop .#opencode
+#
+# To enable OpenCode rules, add the agents input to your flake:
+#   agents = {
+#     url = "git+https://code.m3ta.dev/m3tam3re/AGENTS";
+#     flake = false;
+#   };
+{
+  pkgs,
+  lib ? pkgs.lib,
+  inputs ? null,
+  agents ? null,
+}: let
+  # Import the opencode-rules library
+  m3taLib = import ../lib {lib = pkgs.lib;};
+
+  # Import custom packages
+  customPackages = import ../pkgs {inherit pkgs inputs;};
+
+  # Create rules configuration only if agents input is provided
+  # This demonstrates how to use mkOpencodeRules in a real project
+  rulesConfig = lib.optionalAttrs (agents != null) {
+    rules = m3taLib.opencode-rules.mkOpencodeRules {
+      # Pass the AGENTS repository path
+      inherit agents;
+
+      # Languages relevant to this repository
+      languages = ["python" "typescript" "nix"];
+
+      # Frameworks used in this repo
+      frameworks = ["n8n"];
+
+      # Standard concerns for development
+      concerns = [
+        "coding-style"
+        "naming"
+        "documentation"
+        "testing"
+        "git-workflow"
+        "project-structure"
+      ];
+    };
+  };
+in
+  pkgs.mkShell {
+    name = "opencode-dev";
+
+    # Development tools
+    buildInputs = with pkgs;
+      [
+        # OpenCode AI coding agent (if inputs are available)
+      ]
+      ++ lib.optionals (inputs != null)
+      [inputs.opencode.packages.${pkgs.system}.opencode]
+      ++ [
+        # Task management for AI coding sessions
+        customPackages.td
+
+        # Companion tool for CLI agents (diffs, file trees, task management)
+        customPackages.sidecar
+
+        # Code analysis tools
+        customPackages.code2prompt
+
+        # Nix development tools (for this repo)
+        nil
+        alejandra
+        statix
+        deadnix
+      ];
+
+    # Shell hook that sets up OpenCode rules
+    shellHook = ''
+      echo "🤖 OpenCode Development Environment"
+      echo ""
+      echo "This environment demonstrates the mkOpencodeRules library"
+      echo "provided by the m3ta-nixpkgs repository."
+      echo ""
+
+      ${
+        if (agents != null)
+        then ''
+          # Execute the OpenCode rules shellHook
+          ${rulesConfig.rules.shellHook}
+
+          echo "✅ OpenCode rules configured!"
+        ''
+        else ''
+          echo "⚠️  OpenCode rules not configured"
+          echo ""
+          echo "To enable OpenCode rules, add the agents input to your flake.nix:"
+          echo ""
+          echo "  inputs = {"
+          echo "    m3ta-nixpkgs.url = \"git+https://code.m3ta.dev/m3tam3re/nixpkgs\";"
+          echo "    agents = {"
+          echo "      url = \"git+https://code.m3ta.dev/m3tam3re/AGENTS\";"
+          echo "      flake = false;"
+          echo "    };"
+          echo "  };"
+          echo ""
+          echo "Then pass agents to the shell:"
+          echo "  opencode = import ./opencode.nix { inherit pkgs inputs agents; };"
+        ''
+      }
+
+      echo ""
+      echo "Available tools:"
+      echo "  opencode          - AI coding agent"
+      echo "  td usage --new-session - View current tasks"
+      echo "  sidecar           - Companion tool (diffs, file trees, tasks)"
+      echo "  code2prompt       - Convert code to prompts"
+      echo ""
+      echo "Nix development tools:"
+      echo "  nix flake check    - Check flake validity"
+      echo "  nix fmt .          - Format Nix files"
+      echo "  statix check .     - Lint Nix files"
+      echo "  deadnix .          - Find dead code"
+      echo ""
+      ${
+        if (agents == null)
+        then ''
+          echo "💡 Using mkOpencodeRules in your project:"
+          echo ""
+          echo "Add to your flake.nix:"
+          echo "  inputs = {"
+          echo "    m3ta-nixpkgs.url = \"git+https://code.m3ta.dev/m3tam3re/nixpkgs\";"
+          echo "    agents = {"
+          echo "      url = \"git+https://code.m3ta.dev/m3tam3re/AGENTS\";"
+          echo "      flake = false;"
+          echo "    };"
+          echo "  };"
+          echo ""
+          echo "  outputs = {self, nixpkgs, m3ta-nixpkgs, agents, ...}:"
+          echo "    let"
+          echo "      system = \"x86_64-linux\";"
+          echo "      pkgs = nixpkgs.legacyPackages.''${system};"
+          echo "      m3taLib = m3ta-nixpkgs.lib.''${system};"
+          echo "      rules = m3taLib.opencode-rules.mkOpencodeRules {"
+          echo "        inherit agents;"
+          echo "        languages = [\"python\" \"typescript\"];"
+          echo "        frameworks = [\"n8n\"];"
+          echo "      };"
+          echo "    in {"
+          echo "      devShells.''${system}.default = pkgs.mkShell {"
+          echo "        shellHook = rules.shellHook;"
+          echo "      };"
+          echo "    };"
+        ''
+        else ""
+      }
+      echo ""
+    '';
+  }

shells/python.nix

@@ -1,6 +1,9 @@
 # Modern Python development environment with marimo and uv — Nushell version
 # Usage: nix develop .#python   (drops into Nushell)
-{pkgs}: let
+{
+  pkgs,
+  inputs ? null,
+}: let
   # Use the latest Python available in nixpkgs
   python = pkgs.python313;
 in