diff --git a/flake.lock b/flake.lock
index d96343c..c4e327f 100644
--- a/flake.lock
+++ b/flake.lock
@@ -10,11 +10,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1747514353,
-        "narHash": "sha256-E1WjB+zvDw4x058mg3MIdK5j2huvnNpTEEt2brhg2H8=",
+        "lastModified": 1736955230,
+        "narHash": "sha256-uenf8fv2eG5bKM8C/UvFaiJMZ4IpUFaQxk9OH5t/1gA=",
         "owner": "ryantm",
         "repo": "agenix",
-        "rev": "6697e8babbd8f323dfd5e28f160a0128582c128b",
+        "rev": "e600439ec4c273cf11e06fe4d9d906fb98fa097c",
         "type": "github"
       },
       "original": {
@@ -26,11 +26,11 @@
     "arkenfox-userjs": {
       "flake": false,
       "locked": {
-        "lastModified": 1745247844,
-        "narHash": "sha256-YfgmhyqLH067pjqRSeCpfqFkeaac1nBvsKcrRNkKw7o=",
+        "lastModified": 1741229528,
+        "narHash": "sha256-21DoV4SMueMFRHMsvfsPfQIOtsvRWNY06rE4gB7xFnc=",
         "owner": "arkenfox",
         "repo": "user.js",
-        "rev": "7f852e94fc80fd0aa19f1c948319974e3301187f",
+        "rev": "3d76c74c80485931425464fec0e59d6cb461677a",
         "type": "github"
       },
       "original": {
@@ -39,6 +39,29 @@
         "type": "github"
       }
     },
+    "csharp-language-server": {
+      "inputs": {
+        "flake-utils": [
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1743061507,
+        "narHash": "sha256-M605lQQ035J61tZ48tye8JUCN4MZKXhcTP3SqXqtr4g=",
+        "owner": "SofusA",
+        "repo": "csharp-language-server",
+        "rev": "a119d6002874d9335dbff0a9445f652762eb6685",
+        "type": "github"
+      },
+      "original": {
+        "owner": "SofusA",
+        "repo": "csharp-language-server",
+        "type": "github"
+      }
+    },
     "darwin": {
       "inputs": {
         "nixpkgs": [
@@ -47,11 +70,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1744478979,
-        "narHash": "sha256-dyN+teG9G82G+m+PX/aSAagkC+vUv0SgUw3XkPhQodQ=",
+        "lastModified": 1700795494,
+        "narHash": "sha256-gzGLZSiOhf155FW7262kdHo2YDeugp3VuIFb4/GGng0=",
         "owner": "lnl7",
         "repo": "nix-darwin",
-        "rev": "43975d782b418ebf4969e9ccba82466728c2851b",
+        "rev": "4b9b83d5a92e8c1fbfd8eb27eda375908c11ec4d",
         "type": "github"
       },
       "original": {
@@ -102,17 +125,18 @@
     },
     "firefox-addons": {
       "inputs": {
+        "flake-utils": "flake-utils",
         "nixpkgs": [
           "nixpkgs"
         ]
       },
       "locked": {
         "dir": "pkgs/firefox-addons",
-        "lastModified": 1747541019,
-        "narHash": "sha256-j3GieFJQqdtDLQmGMVhtiPy/3gP3PjlPybKywN4hOOQ=",
+        "lastModified": 1742773104,
+        "narHash": "sha256-dAhrL+gEjNN5U/Sosy7IrX0Y0qPA0U7Gp9TBhqEliNU=",
         "owner": "rycee",
         "repo": "nur-expressions",
-        "rev": "830ffcdb44051917600abb79007e8593e9effc53",
+        "rev": "d74460da63a8c08a69a1f143b04f2ab1a6b2f5c2",
         "type": "gitlab"
       },
       "original": {
@@ -155,37 +179,22 @@
       }
     },
     "flake-compat_3": {
+      "flake": false,
       "locked": {
-        "lastModified": 1747046372,
-        "narHash": "sha256-CIVLLkVgvHYbgI2UpXvIIBJ12HWgX+fjA8Xf8PUmqCY=",
-        "owner": "edolstra",
+        "lastModified": 1717312683,
+        "narHash": "sha256-FrlieJH50AuvagamEvWMIE6D2OAnERuDboFDYAED/dE=",
+        "owner": "nix-community",
         "repo": "flake-compat",
-        "rev": "9100a0f413b0c601e0533d1d94ffd501ce2e7885",
+        "rev": "38fd3954cf65ce6faf3d0d45cd26059e059f07ea",
         "type": "github"
       },
       "original": {
-        "owner": "edolstra",
+        "owner": "nix-community",
         "repo": "flake-compat",
         "type": "github"
       }
     },
     "flake-compat_4": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1746162366,
-        "narHash": "sha256-5SSSZ/oQkwfcAz/o/6TlejlVGqeK08wyREBQ5qFFPhM=",
-        "owner": "nix-community",
-        "repo": "flake-compat",
-        "rev": "0f158086a2ecdbb138cd0429410e44994f1b7e4b",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-community",
-        "repo": "flake-compat",
-        "type": "github"
-      }
-    },
-    "flake-compat_5": {
       "flake": false,
       "locked": {
         "lastModified": 1696426674,
@@ -208,11 +217,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1743550720,
-        "narHash": "sha256-hIshGgKZCgWh6AYJpJmRgFdR3WUbkY04o82X05xqQiY=",
+        "lastModified": 1741352980,
+        "narHash": "sha256-+u2UunDA4Cl5Fci3m7S643HzKmIDAe+fiXrLqYsR2fs=",
         "owner": "hercules-ci",
         "repo": "flake-parts",
-        "rev": "c621e8422220273271f52058f618c94e405bb0f5",
+        "rev": "f4330d22f1c5d2ba72d3d22df5597d123fdb60a9",
         "type": "github"
       },
       "original": {
@@ -243,6 +252,21 @@
       }
     },
     "flake-utils": {
+      "locked": {
+        "lastModified": 1629284811,
+        "narHash": "sha256-JHgasjPR0/J1J3DRm4KxM4zTyAj4IOJY8vIl75v/kPI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "c5d161cc0af116a2e17f54316f0bf43f0819785c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_2": {
       "inputs": {
         "systems": "systems_2"
       },
@@ -289,11 +313,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1745494811,
-        "narHash": "sha256-YZCh2o9Ua1n9uCvrvi5pRxtuVNml8X2a03qIFfRKpFs=",
+        "lastModified": 1703113217,
+        "narHash": "sha256-7ulcXOk63TIT2lVDSExj7XzFx09LpdSAPtvgtM7yQPE=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "abfad3d2958c9e6300a883bd443512c55dfeb1be",
+        "rev": "3bfaacf46133c037bb356193bd2f1765d9dc82c1",
         "type": "github"
       },
       "original": {
@@ -309,11 +333,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1747331121,
-        "narHash": "sha256-3MmiUN/jOHBHQUnjqzg6qKArc17j2OS6jisEppDY4g8=",
+        "lastModified": 1742655702,
+        "narHash": "sha256-jbqlw4sPArFtNtA1s3kLg7/A4fzP4GLk9bGbtUJg0JQ=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "1eec32f0efe3b830927989767a9e6ece0d82d608",
+        "rev": "0948aeedc296f964140d9429223c7e4a0702a1ff",
         "type": "github"
       },
       "original": {
@@ -346,49 +370,6 @@
         "type": "gitlab"
       }
     },
-    "nix-alien": {
-      "inputs": {
-        "flake-compat": "flake-compat_3",
-        "nix-index-database": "nix-index-database",
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1747293822,
-        "narHash": "sha256-1R3Ro+RQCUUnIFZDObP9/2QBLk3xvgbXU67Qii+YZ8s=",
-        "owner": "thiagokokada",
-        "repo": "nix-alien",
-        "rev": "ea7eb3a76520fa8d92879afb819756ffc0bc629e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "thiagokokada",
-        "repo": "nix-alien",
-        "type": "github"
-      }
-    },
-    "nix-index-database": {
-      "inputs": {
-        "nixpkgs": [
-          "nix-alien",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1746934494,
-        "narHash": "sha256-3n6i+F0sDASjkhbvgFDpPDZGp7z19IrRtjfF9TwJpCA=",
-        "owner": "nix-community",
-        "repo": "nix-index-database",
-        "rev": "e9b21b01e4307176b9718a29ac514838e7f6f4ff",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-community",
-        "repo": "nix-index-database",
-        "type": "github"
-      }
-    },
     "nixlib": {
       "locked": {
         "lastModified": 1643502816,
@@ -406,7 +387,7 @@
     },
     "nixos-cosmic": {
       "inputs": {
-        "flake-compat": "flake-compat_4",
+        "flake-compat": "flake-compat_3",
         "nixpkgs": [
           "nixpkgs"
         ],
@@ -414,11 +395,11 @@
         "rust-overlay": "rust-overlay"
       },
       "locked": {
-        "lastModified": 1747566515,
-        "narHash": "sha256-mBT3EypUn1HZ5iRGDmZQPtVNYxQxnkIsasggSCndYjw=",
+        "lastModified": 1742863891,
+        "narHash": "sha256-/mGCIxO7zlWCHOZLaOMRoJgSLpIav0PBKWG3BQddElw=",
         "owner": "lilyinstarlight",
         "repo": "nixos-cosmic",
-        "rev": "93f3add95306179d15f8a6b1cfc87bfdc1702a33",
+        "rev": "366999efebcad2165f472ef93e9c996693bda75d",
         "type": "github"
       },
       "original": {
@@ -429,11 +410,11 @@
     },
     "nixos-hardware": {
       "locked": {
-        "lastModified": 1747129300,
-        "narHash": "sha256-L3clA5YGeYCF47ghsI7Tcex+DnaaN/BbQ4dR2wzoiKg=",
+        "lastModified": 1742806253,
+        "narHash": "sha256-zvQ4GsCJT6MTOzPKLmlFyM+lxo0JGQ0cSFaZSACmWfY=",
         "owner": "NixOS",
         "repo": "nixos-hardware",
-        "rev": "e81fd167b33121269149c57806599045fd33eeed",
+        "rev": "ecaa2d911e77c265c2a5bac8b583c40b0f151726",
         "type": "github"
       },
       "original": {
@@ -444,11 +425,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1747335874,
-        "narHash": "sha256-IKKIXTSYJMmUtE+Kav5Rob8SgLPnfnq4Qu8LyT4gdqQ=",
+        "lastModified": 1742751704,
+        "narHash": "sha256-rBfc+H1dDBUQ2mgVITMGBPI1PGuCznf9rcWX/XIULyE=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ba8b70ee098bc5654c459d6a95dfc498b91ff858",
+        "rev": "f0946fa5f1fb876a9dc2e1850d9d3a4e3f914092",
         "type": "github"
       },
       "original": {
@@ -460,11 +441,11 @@
     },
     "nixpkgs-stable": {
       "locked": {
-        "lastModified": 1747335874,
-        "narHash": "sha256-IKKIXTSYJMmUtE+Kav5Rob8SgLPnfnq4Qu8LyT4gdqQ=",
+        "lastModified": 1742512142,
+        "narHash": "sha256-8XfURTDxOm6+33swQJu/hx6xw1Tznl8vJJN5HwVqckg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ba8b70ee098bc5654c459d6a95dfc498b91ff858",
+        "rev": "7105ae3957700a9646cc4b766f5815b23ed0c682",
         "type": "github"
       },
       "original": {
@@ -476,11 +457,11 @@
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1747327360,
-        "narHash": "sha256-LSmTbiq/nqZR9B2t4MRnWG7cb0KVNU70dB7RT4+wYK4=",
+        "lastModified": 1742669843,
+        "narHash": "sha256-G5n+FOXLXcRx+3hCJ6Rt6ZQyF1zqQ0DL0sWAMn2Nk0w=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "e06158e58f3adee28b139e9c2bcfcc41f8625b46",
+        "rev": "1e5b653dff12029333a6546c11e108ede13052eb",
         "type": "github"
       },
       "original": {
@@ -515,11 +496,11 @@
         "systems": "systems_3"
       },
       "locked": {
-        "lastModified": 1747556457,
-        "narHash": "sha256-L1iSnAQYsveQs1haZ9CcidvYKhYotchzgM9GqYie0Rg=",
+        "lastModified": 1742893502,
+        "narHash": "sha256-W8M7Kzat8ySVY+bBW0FF6jB4xjdb8sLm14OHVyyu0KQ=",
         "owner": "astro",
         "repo": "nix-openwrt-imagebuilder",
-        "rev": "568956f921869b6f36af3809fab4a914ed17082c",
+        "rev": "89d3674159e5606b0c1db636e7c7463b7b976b45",
         "type": "github"
       },
       "original": {
@@ -530,18 +511,18 @@
     },
     "pre-commit-hooks": {
       "inputs": {
-        "flake-compat": "flake-compat_5",
+        "flake-compat": "flake-compat_4",
         "gitignore": "gitignore",
         "nixpkgs": [
           "nixpkgs"
         ]
       },
       "locked": {
-        "lastModified": 1747372754,
-        "narHash": "sha256-2Y53NGIX2vxfie1rOW0Qb86vjRZ7ngizoo+bnXU9D9k=",
+        "lastModified": 1742649964,
+        "narHash": "sha256-DwOTp7nvfi8mRfuL1escHDXabVXFGT1VlPD1JHrtrco=",
         "owner": "cachix",
         "repo": "pre-commit-hooks.nix",
-        "rev": "80479b6ec16fefd9c1db3ea13aeb038c60530f46",
+        "rev": "dcf5072734cb576d2b0c59b2ac44f5050b5eac82",
         "type": "github"
       },
       "original": {
@@ -554,13 +535,13 @@
       "inputs": {
         "agenix": "agenix",
         "arkenfox-userjs": "arkenfox-userjs",
+        "csharp-language-server": "csharp-language-server",
         "deploy-rs": "deploy-rs",
         "firefox-addons": "firefox-addons",
         "flake-parts": "flake-parts",
-        "flake-utils": "flake-utils",
+        "flake-utils": "flake-utils_2",
         "home-manager": "home-manager_2",
         "matrix-appservices": "matrix-appservices",
-        "nix-alien": "nix-alien",
         "nixos-cosmic": "nixos-cosmic",
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs",
@@ -578,11 +559,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1747535902,
-        "narHash": "sha256-rKWBtLcqQeu8PpfKIBn1ORXS2udSH/MwnQFwfSpFOLg=",
+        "lastModified": 1742437918,
+        "narHash": "sha256-Vflb6KJVDikFcM9E231mRN88uk4+jo7BWtaaQMifthI=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "b7a99615d26b82c39b73ccc9026545c3f3403b71",
+        "rev": "f03085549609e49c7bcbbee86a1949057d087199",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index d2c1853..bb05b10 100644
--- a/flake.nix
+++ b/flake.nix
@@ -28,11 +28,6 @@ rec {
 
     flake-utils.url = "github:numtide/flake-utils";
 
-    nix-alien = {
-      url = "github:thiagokokada/nix-alien";
-      inputs.nixpkgs.follows = "nixpkgs";
-    };
-
     home-manager = {
       url = "github:nix-community/home-manager/release-24.11";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -84,6 +79,11 @@ rec {
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
+    csharp-language-server = {
+      url = "github:SofusA/csharp-language-server";
+      # inputs.nixpkgs.follows = "nixpkgs";
+      inputs.flake-utils.follows = "flake-utils";
+    };
   };
 
   outputs =
diff --git a/home/editors/helix/default.nix b/home/editors/helix/default.nix
index ffb18dc..e346dfb 100644
--- a/home/editors/helix/default.nix
+++ b/home/editors/helix/default.nix
@@ -22,12 +22,16 @@ in
     enable = true;
     package = pkgs.unstable.helix;
     languages.language = [
+      {
+        name = "c-sharp";
+        language-servers = [ "roslyn" ];
+        auto-format = true;
+      }
       {
         name = "javascript";
         language-servers = typescriptLanguageServers;
         # TODO also configure eslint for diagnostics
-        # formatter.command = ["eslint_d"];
-        # formatter.args = ["--fix"];
+        # formatter.command = "eslint_d --fix";
         formatter = prettier "typescript";
         auto-format = true;
       }
@@ -55,7 +59,7 @@ in
       }
       {
         name = "nix";
-        # HINT `nix fmt` is a bit slow
+        # `nix fmt` does not support stdin
         formatter.command = "nixfmt";
         language-servers = [
           "nixd"
@@ -70,32 +74,12 @@ in
       }
       {
         name = "protobuf";
-        formatter.command = "buf";
-        formatter.args = [
-          "format"
-          "-w"
-        ];
+        formatter.command = "buf format -w";
         language-servers = [
           "bufls"
           "buf-lint"
         ];
       }
-      {
-        name = "hcl";
-        language-id = "opentofu";
-        language-servers = [ "opentofu-ls" ];
-        injection-regex = "(hcl|tf|tofu)";
-        file-types = [
-          "hcl"
-          "tf"
-          "tofu"
-        ];
-      }
-      {
-        name = "tfvars";
-        language-id = "opentofu-vars";
-        language-servers = [ "opentofu-ls" ];
-      }
       {
         name = "graphql";
         formatter = prettier "graphql";
@@ -156,6 +140,7 @@ in
           };
         };
       };
+      roslyn.command = "csharp-language-server";
       statix = {
         command = "efm-langserver";
         config = {
@@ -227,13 +212,6 @@ in
           };
         };
       };
-      opentofu-ls = {
-        command = "opentofu-ls";
-        args = [ "serve" ];
-        config = {
-          opentofu.path = "tofu";
-        };
-      };
     };
     settings = {
       theme = "dark_plus";
diff --git a/home/editors/lsp.nix b/home/editors/lsp.nix
index 491a001..4f39eec 100644
--- a/home/editors/lsp.nix
+++ b/home/editors/lsp.nix
@@ -4,11 +4,21 @@
   home.packages = with pkgs; [
     # language servers
     efm-langserver
+    unstable.roslyn-ls
+    (pkgs.symlinkJoin {
+      name = "csharp-language-server";
+      paths = [ inputs.csharp-language-server.packages.${system}.csharp-language-server ];
+      buildInputs = [ pkgs.makeWrapper ];
+      postBuild = ''
+        wrapProgram $out/bin/csharp-language-server \
+          --prefix PATH : "${pkgs.lib.makeBinPath [ pkgs.dotnet-sdk_9 ]}"
+      '';
+    })
+    omnisharp-roslyn
     nil
     unstable.nixd
     nls
     terraform-ls
-    unstable.opentofu-ls
     pyright
     nodePackages.bash-language-server
     nodePackages.vim-language-server
@@ -21,7 +31,6 @@
     haskellPackages.haskell-language-server
     rust-analyzer
     sumneko-lua-language-server
-    marksman
 
     # linters & formatters
     topiary
diff --git a/home/shell/zellij.nix b/home/shell/zellij.nix
index 1555ef8..57f3a47 100644
--- a/home/shell/zellij.nix
+++ b/home/shell/zellij.nix
@@ -7,7 +7,6 @@
   programs.zellij.settings = {
     default_layout = "compact"; # or default
     default_mode = "normal";
-    show_startup_tips = false;
     ui.pane_frames = {
       hide_session_name = true;
     };
diff --git a/system/common.nix b/system/common.nix
index 2d8bded..c7202db 100644
--- a/system/common.nix
+++ b/system/common.nix
@@ -5,7 +5,6 @@
     ./zram.nix
     ./i18n.nix
     ./nix.nix
-    ./nix-ld.nix
     ./networking.nix
     ./hardened.nix
   ];
diff --git a/system/nix-ld.nix b/system/nix-ld.nix
deleted file mode 100644
index caaab62..0000000
--- a/system/nix-ld.nix
+++ /dev/null
@@ -1,9 +0,0 @@
-{ inputs, system, ... }:
-
-{
-  environment.systemPackages = [
-    inputs.nix-alien.packages.${system}.nix-alien
-  ];
-
-  programs.nix-ld.enable = true;
-}