From f725506aeaf72437f9137193cddbdc1e46bf44ce Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Franti=C5=A1ek=20Boh=C3=A1=C4=8Dek?=
 <frantisek.bohacek@braiinsforge.com>
Date: Sat, 26 Sep 2026 21:52:08 +0200
Subject: [PATCH] Add library: mkEnvironment, mkSkill and mkSkillModule

---
 lib/default.nix | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 lib/default.nix

diff --git a/lib/default.nix b/lib/default.nix
new file mode 100644
index 0000000000000000000000000000000000000000..787c44ad30f2e497f2ed17a49f3b3683a493ff68
--- /dev/null
+++ b/lib/default.nix
@@ -0,0 +1,84 @@
+{ lib, defaultPackages }:
+let
+  safeName = name: builtins.match "[A-Za-z0-9][A-Za-z0-9._-]*" name != null;
+
+  # Package a skill directory (containing SKILL.md).
+  #   runtimeInputs: packages put on PATH of every launcher that enables the skill
+  #   skills:        other mkSkill packages this skill depends on
+  mkSkill =
+    {
+      pkgs,
+      name,
+      src,
+      runtimeInputs ? [ ],
+      skills ? [ ],
+    }:
+    assert lib.assertMsg (safeName name) "mkSkill: unsafe skill name '${name}'";
+    pkgs.runCommand "skill-${name}"
+      {
+        passthru = {
+          skillName = name;
+          inherit runtimeInputs;
+          skillDeps = skills;
+        };
+      }
+      ''
+        if [ ! -f ${src}/SKILL.md ]; then
+          echo "mkSkill: ${name}: SKILL.md is missing in ${src}" >&2
+          exit 1
+        fi
+        cp -r ${src} $out
+        chmod -R u+w $out
+      '';
+in
+{
+  inherit safeName mkSkill;
+
+  # Evaluate an environment from a list of modules.
+  mkEnvironment =
+    {
+      pkgs,
+      modules ? [ ],
+    }:
+    let
+      eval = lib.evalModules {
+        modules = [
+          ../modules/core.nix
+          ../modules/claude.nix
+          ../modules/codex.nix
+          ../modules/launcher.nix
+          {
+            _module.args = {
+              inherit pkgs;
+              agentEnvLib = { inherit safeName; };
+            };
+            claude.package = lib.mkDefault (defaultPackages pkgs.stdenv.hostPlatform.system).claude;
+            codex.package = lib.mkDefault (defaultPackages pkgs.stdenv.hostPlatform.system).codex;
+          }
+        ]
+        ++ modules;
+      };
+      failed = map (a: a.message) (lib.filter (a: !a.assertion) eval.config.assertions);
+      checked =
+        if failed == [ ] then
+          eval.config
+        else
+          throw "agent-environments:\n${lib.concatMapStringsSep "\n" (m: "- ${m}") failed}";
+    in
+    {
+      config = checked;
+      inherit (checked.build) package launchers;
+    };
+
+  # A module declaring `modules.skills.<name>.enable` for a packaged skill.
+  mkSkillModule =
+    skill:
+    { config, lib, ... }:
+    {
+      options.modules.skills.${skill.skillName}.enable =
+        lib.mkEnableOption "the ${skill.skillName} skill";
+      config = lib.mkIf config.modules.skills.${skill.skillName}.enable {
+        skills.packages = [ skill ];
+      };
+    };
+}