devshell: add black, mypy and corresponding python-lsp-server plugins

flake.nix

@@ -7,8 +7,9 @@
     let
       system = "x86_64-linux";
       pkgs = nixpkgs.legacyPackages.${system};
+      pythonPackages = pkgs.python310Packages;
       selfprivacy-graphql-api = pkgs.callPackage ./default.nix {
-        pythonPackages = pkgs.python310Packages;
+        inherit pythonPackages;
         rev = self.shortRev or self.dirtyShortRev or "dirty";
       };
       python = self.packages.${system}.default.pythonModule;
@@ -71,15 +72,26 @@
         import ./nixos/module.nix self.packages.${system}.default;
       devShells.${system}.default = pkgs.mkShell {
         name = "SP API dev shell";
-        packages = with pkgs; [
-          python-env
-          rclone
-          redis
-          restic
-          self.packages.${system}.pytest-vm
-          # FIXME consider loading this explicitly only after ArchLinux issue is solved
-          self.checks.x86_64-linux.default.driverInteractive
-        ];
+        packages = with pythonPackages;
+          [
+            black
+            mypy
+            pylsp-mypy
+            python-lsp-black
+            python-lsp-server
+          ] ++
+          (with pkgs;
+          [
+            nixpkgs-fmt
+            rclone
+            redis
+            restic
+            self.packages.${system}.pytest-vm
+            # FIXME consider loading this explicitly only after ArchLinux issue is solved
+            self.checks.x86_64-linux.default.driverInteractive
+            # the target API application python environment
+            python-env
+          ]);
         shellHook = ''
           # envs set with export and as attributes are treated differently.
           # for example. printenv <Name> will not fetch the value of an attribute.