added documentation and dev tools

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -1 +1,4 @@
 result
+*.AppImage
+
+.direnv/

README.md

@@ -0,0 +1,23 @@
+# Story Architect Flake
+
+This flake packages the [Story Architect](https://github.com/story-apps/starc) AppImage.
+
+## Build
+
+```txt
+nix build
+```
+
+## Developing
+
+```txt
+nix develop
+nix run .#dev
+```
+
+The `nix run .#dev` command will download the AppImage used for building.
+It can then be inspected locally with tools like `file` and `appimage-run`, which are offered by the `nix develop` command.
+
+### Resources
+
+* [Nix Manual](https://nixos.org/manual/nixpkgs/stable/#sec-pkgs-appimageTools)

flake.nix

@@ -20,6 +20,11 @@
       sha256 = "sha256-wixqb1cV+WEhgxsl2CeOjrid4P0daHqh0O40h2iPst4=";
     };
 
+    appimage = pkgs.fetchurl {
+      url = "https://github.com/story-apps/starc/releases/download/v${version}/starc-setup.AppImage";
+      sha256 = "sha256-KLawvuLyqd7aPidH3ghr7mLl9NFQ7nduhnxAq0RpToQ=";
+    };
+
     desktopItem = pkgs.makeDesktopItem {
       exec = name;
 
@@ -39,10 +44,7 @@
       default = pkgs.appimageTools.wrapType1 {
         inherit name;
 
-        src = pkgs.fetchurl {
-          url = "https://github.com/story-apps/starc/releases/download/v${version}/starc-setup.AppImage";
-          sha256 = "sha256-KLawvuLyqd7aPidH3ghr7mLl9NFQ7nduhnxAq0RpToQ=";
-        };
+        src = appimage;
 
         extraInstallCommands = ''
           # Install .desktop file
@@ -59,5 +61,23 @@
         '';
       };
     };
+
+    apps.${system} = {
+      dev = {
+        program = "${pkgs.writeShellScript "download-appimage" ''
+          ${pkgs.curl}/bin/curl ${appimage.url} -Lo ${name}.AppImage
+        ''}";
+        type = "app";
+      };
+    };
+
+    devShells.${system} = {
+      default = pkgs.mkShellNoCC {
+        packages = with pkgs; [
+          appimage-run
+          file
+        ];
+      };
+    };
   };
 }