diff --git a/hosts/hs/configuration.nix b/hosts/hs/configuration.nix
index 09f96ec..f9e38fb 100644
--- a/hosts/hs/configuration.nix
+++ b/hosts/hs/configuration.nix
@@ -130,7 +130,6 @@
 
     transmission = {
       enable = true;
-      port = 9091;
       # the following json is merged to this attrset, it must have `rpc-username` and `rpc-password`
       credentialsFile = "/mnt/archivio/transmission/credentials.json";
       settings = {
@@ -138,6 +137,7 @@
         incomplete-dir = "/mnt/archivio/transmission/.incomplete";
         incomplete-dir-enabled = true;
 
+        rpc-port = 9091;
         rpc-whitelist-enabled = false;
         rpc-host-whitelist-enabled = false;
         rpc-authentication-required = true;
@@ -268,7 +268,7 @@
       ydnsUpdater = pkgs.writeScriptBin "ydnsUpdater" ''
         #!${pkgs.stdenv.shell}
         USER="andrea.ciceri@autistici.org"
-        PASSWORD=$(${pkgs.stdenv}/bin/cat /home/ccr/.ydns-password)
+        PASSWORD=$(cat /home/ccr/.ydns-password)
         DOMAIN="ccr.ydns.eu"
 
         for SUBDOMAIN in "books" "music" "sync" "torrent" "gate" "cam"
diff --git a/hosts/pc/configuration.nix b/hosts/pc/configuration.nix
index 9432879..b0f448f 100644
--- a/hosts/pc/configuration.nix
+++ b/hosts/pc/configuration.nix
@@ -68,11 +68,22 @@
   };
 
   systemd.services.nix-daemon.serviceConfig = {
-    LimitNOFILE = lib.mkForce 131072; # should help with fds errors due to experimental feature `ca-derivations`
+    LimitNOFILE = lib.mkForce "Infinity"; # 131072; # should help with fds errors due to experimental feature `ca-derivations`
   };
 
   networking.firewall = {
     enable = true;
     allowPing = true;
   };
+
+
+  services.hydra = {
+    enable = true;
+    hydraURL = "http://localhost:3000"; # externally visible URL
+    notificationSender = "hydra@localhost"; # e-mail of hydra service
+    # a standalone hydra will require you to unset the buildMachinesFiles list to avoid using a nonexistant /etc/nix/machines
+    buildMachinesFiles = [ ];
+    # you will probably also want, otherwise *everything* will be built from scratch
+    useSubstitutes = true;
+  };
 }
diff --git a/pkgs/emacs/default.nix b/pkgs/emacs/default.nix
index 7305748..2650b58 100644
--- a/pkgs/emacs/default.nix
+++ b/pkgs/emacs/default.nix
@@ -9,6 +9,12 @@ emacsWithPackages (
   ) ++ (
     with epkgs.melpaPackages; [
       aggressive-indent
+      pkgs.emacs28Packages.tree-sitter-langs
+      tree-sitter
+      # ts-fold
+      tree-edit
+      evil-tree-edit
+      pkgs.emacs28Packages.tsc
       all-the-icons
       company
       company-nixos-options
diff --git a/profiles/core/default.nix b/profiles/core/default.nix
index 77f1853..7fead8e 100644
--- a/profiles/core/default.nix
+++ b/profiles/core/default.nix
@@ -8,27 +8,28 @@ in
   environment = {
 
     systemPackages = with pkgs; [
+      #skim
       bat
       bat-extras.batman
       binutils
+      bottom
       coreutils
       curl
       dnsutils
       dosfstools
       fd
       git
-      htop
       glances
-      bottom
       gptfdisk
+      htop
       iputils
       jq
+      lsof
       manix
       moreutils
       nix-index
       nmap
       ripgrep
-      #skim
       tealdeer
       tmux
       usbutils
@@ -59,7 +60,7 @@ in
     autoOptimiseStore = true;
     useSandbox = true;
     allowedUsers = [ "@wheel" ];
-    trustedUsers = [ "root" "@wheel" ];
+    trustedUsers = [ "root" "@wheel" "hydra" "hydra-www" ];
   };
 
   services.earlyoom.enable = true;
diff --git a/users/root/default.nix b/users/root/default.nix
index 0368a07..2c440f5 100644
--- a/users/root/default.nix
+++ b/users/root/default.nix
@@ -5,4 +5,15 @@
     password = "nixos";
     shell = pkgs.zsh;
   };
+
+  # FIXME: (temporary?) workaround for https://github.com/NixOS/nixpkgs/issues/169193
+  home-manager.users.ccr.programs.git = {
+    enable = true;
+    extraConfig.safe.directory = "/home/ccr/fleet";
+  };
+  home-manager.users.root.programs.git = {
+    enable = true;
+    extraConfig.safe.directory = "/home/ccr/fleet";
+  };
+
 }