diff --git a/.commandcode/taste/taste.md b/.commandcode/taste/taste.md
new file mode 100644
index 0000000..4b588b2
--- /dev/null
+++ b/.commandcode/taste/taste.md
@@ -0,0 +1,8 @@
+# nix
+- For R.nvim in the Nix wrapper, both RNVIM_COMPLDIR (C server compilation) and a writable R_LIBS_USER directory (nvimcom R package installation) must be configured — fixing only one leaves permission errors in the other. Confidence: 0.65
+- For R.nvim writable directories (RNVIM_COMPLDIR, R_LIBS_USER, TMPDIR), prefer project-local paths (e.g., $PWD/.Rlibs) over global cache paths — the cache approach may let the build succeed but still fail at runtime. Confidence: 0.70
+
+# Taste (Continuously Learned by [CommandCode][cmd])
+
+[cmd]: https://commandcode.ai/
+
diff --git a/flake.nix b/flake.nix
index 8482605..be28255 100644
--- a/flake.nix
+++ b/flake.nix
@@ -46,7 +46,7 @@
         nix = true;
         optional = false;
         python = false;
-        r = false;
+        r = true;
       };
       settings = {
         lang_packages = {
@@ -199,7 +199,8 @@
           zk
         ];
 
-        shellPackages = [nvimPkg]
+        shellPackages =
+          [nvimPkg]
           ++ pkgs.lib.optionals cfg.cats.python pythonPackages
           ++ pkgs.lib.optionals cfg.cats.r rPackages
           ++ pkgs.lib.optionals cfg.cats.julia juliaPackages
@@ -210,7 +211,13 @@
           packages = shellPackages;
           nativeBuildInputs = with pkgs; [] ++ (pkgs.lib.optionals cfg.cats.optional [devenv]);
           inputsFrom = [];
-          shellHook = "";
+          shellHook = ''
+            echo 'I am a NixShell'
+            export R_HOME=$(R RHOME)
+            export R_LIBS_SITE=$(strings "$(command -v R)" | grep -oP '/nix/store/[^:]+/library' | sort -u | paste -sd: -)
+            export R_LIBS_USER="$PWD/.r-libs"
+            mkdir -p "$R_LIBS_USER"
+          '';
         };
       }
     );
diff --git a/modules/module/settings/cats.nix b/modules/module/settings/cats.nix
index 22b3638..3da043e 100644
--- a/modules/module/settings/cats.nix
+++ b/modules/module/settings/cats.nix
@@ -43,7 +43,7 @@
     nix = lib.mkDefault true;
     optional = lib.mkDefault false;
     python = lib.mkDefault false;
-    r = lib.mkDefault false;
+    r = lib.mkDefault true;
     test = lib.mkDefault false;
     treesitterParsers = lib.mkDefault true;
     utils = lib.mkDefault true;
diff --git a/modules/module/settings/env.nix b/modules/module/settings/env.nix
index 2ae4b9c..0749ede 100644
--- a/modules/module/settings/env.nix
+++ b/modules/module/settings/env.nix
@@ -11,12 +11,17 @@
       UV_PYTHON_DOWNLOADS = "never";
       UV_PYTHON = pkgs.python.interpreter;
     })
+    (lib.mkIf (config.cats.r or false) {
+      RNVIM_COMPLDIR = "$PWD/.r-compl";
+      R_LIBS_USER = "${pkgs.nvimcom}:$PWD/.Rlibs";
+      TMPDIR = "$PWD/.r-tmp";
+    })
   ];
 
   # Environment variables with defaults (can be overridden by user)
   config.envDefault = lib.mkMerge [
     (lib.mkIf (config.cats.r or false) {
-      R_LIBS_USER =  "./.Rlibs";
+      R_LIBS_USER =  "${pkgs.nvimcom}:$PWD/.Rlibs";
     })
   ];
 }
diff --git a/modules/module/specs/plugins.nix b/modules/module/specs/plugins.nix
index ded8195..eb9d499 100644
--- a/modules/module/specs/plugins.nix
+++ b/modules/module/specs/plugins.nix
@@ -11,7 +11,13 @@
 
   config.specs.r = {
     data = with pkgs.vimPlugins; [
-      config.nvim-lib.neovimPlugins.r
+      (config.nvim-lib.neovimPlugins.r.overrideAttrs (old: {
+        postInstall = (old.postInstall or "") + ''
+          mkdir -p $out/rnvimserver
+          cp ${pkgs.nvimcom}/bin/rnvimserver $out/rnvimserver/rnvimserver
+          chmod +x $out/rnvimserver/rnvimserver
+        '';
+      }))
       quarto-nvim
       {
         data = otter-nvim;
diff --git a/overlays/r.nix b/overlays/r.nix
index 2fb71c8..22c42fa 100644
--- a/overlays/r.nix
+++ b/overlays/r.nix
@@ -33,12 +33,38 @@
     overlays = [inputs.fran.overlays.default];
   }; # rixpkgs.legacyPackages.${prev.stdenv.hostPlatform.system};
 
+  # Pre-build nvimcom from R.nvim plugin source so R.nvim never tries to
+  # compile it at runtime into the read-only nix store.
+  nvimcom = final.stdenv.mkDerivation {
+    pname = "nvimcom";
+    version = "0.9.92";
+    src = inputs.plugins-r;
+    nativeBuildInputs = [
+      (rpkgs.rWrapper.override { packages = []; })
+    ];
+    buildPhase = ''
+      mkdir -p $out/bin
+      R CMD INSTALL -l $out nvimcom
+      cd rnvimserver
+      $CC -pthread -O2 -Wall \
+        complete.c resolve.c hover.c definition.c signature.c \
+        rhelp.c chunk.c roxygen.c data_structures.c logging.c \
+        rnvimserver.c obbr.c tcp.c utilities.c ../nvimcom/src/common.c \
+        -o $out/bin/rnvimserver
+      cd ..
+      mkdir -p $out/nvimcom/bin
+      cp $out/bin/rnvimserver $out/nvimcom/bin/rnvimserver
+      chmod +x $out/bin/rnvimserver $out/nvimcom/bin/rnvimserver
+    '';
+    installPhase = "true";
+  };
+
   # Standard R packages used by default in rWrapper and quarto
   reqPkgs = with rpkgs.rPackages; [
     #    languageserver
   ];
 in {
-  inherit rpkgs;
+  inherit rpkgs nvimcom;
   baseRPackages = reqPkgs;
 
   # R wrapper with standard packages
diff --git a/plugin/21_datascience.lua b/plugin/21_datascience.lua
index 118ee20..62d8f49 100644
--- a/plugin/21_datascience.lua
+++ b/plugin/21_datascience.lua
@@ -44,6 +44,12 @@ end)
 -- r
 now(function()
   if nix.get_cat("r", false) then
+    local cwd = vim.fn.getcwd(-1)
+    vim.env.RNVIM_COMPLDIR = cwd .. "/.r-compl"
+    vim.env.R_LIBS_USER = (vim.env.R_LIBS_USER or ""):gsub("%$PWD", cwd)
+    vim.env.TMPDIR = cwd .. "/.r-tmp"
+    vim.fn.mkdir(vim.env.RNVIM_COMPLDIR, "p")
+    vim.fn.mkdir(vim.env.TMPDIR, "p")
     vim.g.rout_follow_colorscheme = true
     require("r").setup({
       -- Create a table with the options to be passed to setup()