Nix flake with a dev shell for everything

nix develop: Go, gopls, shellcheck, make, curl, jq, Python, Node.js,
oxipng and ImageMagick; on Linux also Ghostty, Xvfb, xdotool, DejaVu fonts
and Chromium for the README screenshots and the webOS app.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -140,6 +140,8 @@ TV's Developer Mode; see [webos/README.md](webos/README.md).
 
 ## Development
 
+`nix develop` opens a shell with everything below (Go, shellcheck, Node.js, Python, the screenshot
+tools and Chromium; the flake is in [flake.nix](flake.nix)); without Nix, install what you use.
 `dev/` has a compose file with pinned Radarr, Sonarr and SABnzbd containers plus a fake indexer;
 see [dev/README.md](dev/README.md).
 `make test` runs vet and the unit tests. The screenshots are made with

dev/screenshots/README.md

@@ -7,8 +7,8 @@ keys (masked in the Config view anyway).
 
 ```sh
 dev/screenshots/take.sh
-# on NixOS, with the tools from nixpkgs:
+# with Nix, everything from the flake's dev shell:
-nix-shell -p xvfb-run xorg-server xdotool imagemagick oxipng --run dev/screenshots/take.sh
+nix develop --command dev/screenshots/take.sh
 ```
 
 Needs Go, Python 3, Ghostty, `xvfb-run` (Xvfb), `xdotool`, ImageMagick 7 and fontconfig with the

dev/screenshots/take.sh

@@ -5,7 +5,7 @@
 #
 # Needs: go, python3, ghostty, xvfb-run (Xvfb), xdotool, ImageMagick 7,
 # fontconfig with DejaVu fonts; oxipng optional. On NixOS:
-#   nix-shell -p xvfb-run xorg-server xdotool imagemagick oxipng --run dev/screenshots/take.sh
+#   nix develop --command dev/screenshots/take.sh
 set -euo pipefail
 here=$(cd "$(dirname "$0")" && pwd)
 repo=$(cd "$here/../.." && pwd)

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1792773339,
+        "narHash": "sha256-rZLrzrC6i+jnTAlvPZHogKDulY7WWDEv9hJeHieO7Zw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "3ec636362e1816bc2f0888fa0fa2c69f1bc9e504",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,62 @@
+{
+  description = "arr-tui: a terminal UI (and webOS TV app) for Radarr, Sonarr and SABnzbd";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs = { self, nixpkgs }:
+    let
+      systems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forAll = f: nixpkgs.lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
+    in
+    {
+      # nix develop: everything make test, the release script, the README
+      # screenshots (dev/screenshots) and the webOS app (webos/) need.
+      # Containers for dev/up.sh (docker or podman) come from the system.
+      devShells = forAll (pkgs: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [
+            # arr-tui
+            go
+            gopls
+            gnumake
+            shellcheck
+            git
+            # scripts/release.sh, dev/up.sh
+            curl
+            jq
+            # dev/screenshots (fake services), webos (app, tests, ares CLI)
+            python3
+            nodejs_24
+            # README pictures: oxipng compresses them
+            oxipng
+            imagemagick
+          ] ++ lib.optionals stdenv.hostPlatform.isLinux [
+            # dev/screenshots/take.sh: Ghostty on a virtual X display
+            ghostty
+            xvfb-run
+            xorg-server
+            xdotool
+            fontconfig
+            dejavu_fonts
+            # webos/dev/drive.mjs
+            chromium
+          ];
+
+          # posters.sh asks fontconfig for the DejaVu fonts: the system's
+          # fonts plus DejaVu.
+          FONTCONFIG_FILE = pkgs.lib.optionalString pkgs.stdenv.hostPlatform.isLinux (pkgs.writeText "fonts.conf" ''
+            <?xml version="1.0"?>
+            <!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
+            <fontconfig>
+              <include ignore_missing="yes">/etc/fonts/fonts.conf</include>
+              <dir>${pkgs.dejavu_fonts}/share/fonts</dir>
+            </fontconfig>
+          '');
+
+          shellHook = pkgs.lib.optionalString pkgs.stdenv.hostPlatform.isLinux ''
+            export CHROMIUM=${pkgs.chromium}/bin/chromium
+          '';
+        };
+      });
+    };
+}

webos/README.md

@@ -77,6 +77,8 @@ The app targets webOS 5 (2020 TVs, Chromium 68) and newer.
 
 ## Development
 
+`nix develop` in the repository has Node.js and Chromium (and sets `$CHROMIUM`).
+
 ```sh
 npm run typecheck
 npm test             # unit tests (Node's test runner)