feat(home): add declarative Neovim via nixvim

New `nixvim` flake input (release branch, follows nixpkgs) drives the whole
editor from `modules/nvim.nix`, wired into `homeModules.default`. Minimal LSP
baseline (`nixd`, `bashls`) exposed as `local.nvim.lspServers`; blink-cmp,
Telescope, neo-tree, lualine, treesitter, colorizer, gitsigns, toggleterm, and a
catppuccin theme. which-key groups plus `<leader>?`/`<leader>sk` give an
in-editor keybind cheatsheet; per-directory session persistence with
`sessionoptions` + a `PersistenceSavePre` neo-tree close for clean layouts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

flake.lock

@@ -1,5 +1,26 @@
 {
   "nodes": {
+    "flake-parts": {
+      "inputs": {
+        "nixpkgs-lib": [
+          "nixvim",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1778716662,
+        "narHash": "sha256-m1Yf0wZ8j1OHjTc2UwHwyQRSnNeSgLJOd7q5Y45hzi4=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "f7c1a2d347e4c52d5fb8d10cb4d94b5884e546fb",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
     "home-manager": {
       "inputs": {
         "nixpkgs": [
@@ -37,10 +58,34 @@
         "type": "github"
       }
     },
+    "nixvim": {
+      "inputs": {
+        "flake-parts": "flake-parts",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1782919967,
+        "narHash": "sha256-pRwjfB5HQJ3m8J8bOR43pPHtHI7VUJSqwLA3P06cOY0=",
+        "owner": "nix-community",
+        "repo": "nixvim",
+        "rev": "667c8471f4a0fb24d702d1a61af8609f1a5f1ba6",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "ref": "nixos-26.05",
+        "repo": "nixvim",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "home-manager": "home-manager",
         "nixpkgs": "nixpkgs",
+        "nixvim": "nixvim",
         "rust-overlay": "rust-overlay"
       }
     },
@@ -63,6 +108,21 @@
         "repo": "rust-overlay",
         "type": "github"
       }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -17,9 +17,20 @@
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
+    # nixvim: declarative Neovim as home-manager options — the whole editor
+    # (plugins, LSP, keymaps) lives in modules/nvim.nix, pinned by this flake's
+    # lock. Track the release branch matching nixpkgs (a mismatched branch fails
+    # with `vimPlugins.<name> not found`). `follows` keeps one nixpkgs: both are
+    # on the same stable channel, so the version skew nixvim warns about (only an
+    # issue against unstable) does not arise here.
+    nixvim = {
+      url = "github:nix-community/nixvim/nixos-26.05";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
-  outputs = inputs@{ self, nixpkgs, home-manager, rust-overlay, ... }:
+  outputs = inputs@{ self, nixpkgs, home-manager, rust-overlay, nixvim, ... }:
     let
       system = "x86_64-linux";
     in {
@@ -28,7 +39,11 @@
       #   imports = [ config.nixosModules.default ];
       #   home-manager.users.<you>.imports = [ config.homeModules.default ];
       nixosModules.default = import ./modules/nixos.nix;
-      homeModules.default = import ./modules/home.nix;
+      # nixvim's home-manager module rides along so `modules/nvim.nix` can set
+      # `programs.nixvim.*`; consumers get the editor by importing this one module.
+      homeModules.default = {
+        imports = [ nixvim.homeModules.nixvim ./modules/home.nix ];
+      };
 
       # ---- The example / template host -----------------------------------
       # Real and buildable; dogfoods the modules above. Clone, replace

modules/home.nix

@@ -122,7 +122,7 @@ let
   '';
 in
 {
-  imports = [ ./gpg.nix ./media.nix ./texlive.nix ./librewolf.nix ./mc.nix ./mime.nix ./hyprland-workspaces.nix ];
+  imports = [ ./gpg.nix ./media.nix ./texlive.nix ./librewolf.nix ./mc.nix ./mime.nix ./hyprland-workspaces.nix ./nvim.nix ];
 
   # Put ~/.local/bin (the XDG user-bin dir) on PATH so hand-dropped scripts run
   # by name without wiring each through nix.

modules/nvim.nix

@@ -0,0 +1,272 @@
+# Neovim, configured declaratively via nixvim. The editor — plugins, LSP,
+# completion, keymaps — is defined here and pinned by the flake lock; nothing is
+# downloaded at runtime, unlike an imperative distro (NvChad/LazyVim). The nixvim
+# home-manager module that provides `programs.nixvim` is imported for consumers by
+# `homeModules.default` in flake.nix, so this file only sets options.
+#
+# Consumer knobs (the option-with-default contract): `local.nvim.enable` to opt
+# out wholesale, `local.nvim.colorscheme` to swap theme in one line, and
+# `local.nvim.lspServers` to reshape the language set. Everything else is
+# opinionated — but since nixvim exposes every plugin as an option, a consumer can
+# still override any `programs.nixvim.plugins.*` directly from their own config.
+
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.local.nvim;
+in
+{
+  options.local.nvim = {
+    enable = lib.mkOption {
+      type = lib.types.bool;
+      default = true;
+      description = "Whether to enable the nixvim-based Neovim setup.";
+    };
+
+    colorscheme = lib.mkOption {
+      type = lib.types.str;
+      default = "catppuccin";
+      example = "tokyonight";
+      description = ''
+        nixvim colorscheme module to enable (the attr under `colorschemes.*`,
+        e.g. "catppuccin", "tokyonight", "gruvbox"). Catppuccin is tuned below
+        (mocha flavour); for another scheme set its `colorschemes.<name>.settings`
+        from your own config if you want to tweak it.
+      '';
+    };
+
+    lspServers = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [
+        "nixd"   # Nix — this repo's own language, so a sensible public baseline
+        "bashls" # Shell — likewise generic enough to default on
+      ];
+      example = [ "nixd" "bashls" "rust_analyzer" "basedpyright" ];
+      description = ''
+        lspconfig server names to enable under `plugins.lsp.servers.<name>`.
+        Each must exist in nixvim's server list and its binary in nixpkgs. The
+        public default is deliberately minimal (Nix + shell); a consumer sets its
+        own language set here — and any per-server tuning a pick needs (e.g.
+        rust_analyzer's `installRustc`) via `programs.nixvim.plugins.lsp.servers`.
+        Note: standalone Lua wants "lua_ls", but Lua embedded in Nix strings is
+        invisible to any LSP, so it is not needed just to edit this config.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    programs.nixvim = {
+      enable = true;
+
+      # Point nixvim at our (followed) nixpkgs instead of the rev it pins. Both
+      # track nixos-26.05, so the version skew nixvim warns about does not arise,
+      # and this keeps a single nixpkgs in the closure. Setting it explicitly is
+      # also what silences that warning.
+      nixpkgs.source = pkgs.path;
+
+      # System clipboard on Wayland: yanks go to / puts read from wl-clipboard,
+      # so copy/paste crosses the nvim boundary. Enabling the provider pulls the
+      # wl-clipboard binaries in as a dependency.
+      clipboard = {
+        register = "unnamedplus";
+        providers.wl-copy.enable = true;
+      };
+
+      globals = {
+        mapleader = " ";
+        maplocalleader = " ";
+      };
+
+      opts = {
+        number = true;
+        relativenumber = true;      # relative line numbers for quick j/k motions
+        signcolumn = "yes";         # always show the gutter so text doesn't jump
+        cursorline = true;
+        termguicolors = true;       # 24-bit colour, required by catppuccin & co.
+        scrolloff = 8;              # keep 8 lines of context around the cursor
+
+        expandtab = true;           # spaces, not tabs
+        shiftwidth = 2;
+        tabstop = 2;
+        smartindent = true;
+
+        ignorecase = true;          # case-insensitive search…
+        smartcase = true;           # …unless the query has a capital
+        undofile = true;            # persistent undo across sessions
+        splitright = true;
+        splitbelow = true;
+
+        # What :mksession stores (persistence.nvim). Drops "blank" and "terminal"
+        # from nvim's default so empty/plugin windows (neo-tree, toggleterm) aren't
+        # serialised — they restore as broken empty splits otherwise. Adds
+        # "globals", which some plugins rely on. Pairs with the PersistenceSavePre
+        # neo-tree close below.
+        sessionoptions = "buffers,curdir,folds,globals,tabpages,winsize";
+      };
+
+      # Theme. Swap via local.nvim.colorscheme; catppuccin gets the mocha flavour.
+      # mkMerge keeps the computed `${cfg.colorscheme}` key from colliding with the
+      # literal `catppuccin` one when they happen to be the same attr.
+      colorschemes = lib.mkMerge [
+        { ${cfg.colorscheme}.enable = true; }
+        (lib.mkIf (cfg.colorscheme == "catppuccin") {
+          catppuccin.settings.flavour = "mocha";
+        })
+      ];
+
+      plugins = {
+        # Shared icon set for the tree, statusline, completion menu.
+        web-devicons.enable = true;
+
+        # Syntax via tree-sitter. The default grammar set is broad, so most
+        # languages get highlighting without an LSP or any per-language wiring.
+        treesitter = {
+          enable = true;
+          settings = {
+            highlight.enable = true;
+            indent.enable = true;
+          };
+        };
+
+        # LSP. Servers come from local.nvim.lspServers; blink-cmp feeds its
+        # completion capabilities in automatically (setupLspCapabilities).
+        lsp = {
+          enable = true;
+          servers = lib.genAttrs cfg.lspServers (_: { enable = true; });
+          keymaps = {
+            silent = true;
+            lspBuf = {
+              gd = "definition";
+              gD = "declaration";
+              K = "hover";
+              "<leader>rn" = "rename";
+              "<leader>ca" = "code_action";
+            };
+            # gr/gi (references, implementations) are wired to Telescope pickers in
+            # the global keymaps below instead — fuzzy + preview browsing beats the
+            # quickfix list that vim.lsp.buf.references would populate. gd stays a
+            # direct jump here (usually one target; Ctrl-o returns).
+            diagnostic = {
+              # Idiomatic vim bracket pair for stepping a list, kept as the public
+              # default. A consumer whose layout makes brackets awkward (they need
+              # AltGr on QWERTZ) can add comfortable aliases from their own config:
+              # this option is attrsOf, so extra keys merge in without conflict.
+              "[d" = "goto_prev";
+              "]d" = "goto_next";
+              "<leader>ds" = "open_float";  # show the diagnostic under the cursor
+            };
+          };
+        };
+
+        # Completion. blink.cmp — faster and lighter to configure than nvim-cmp.
+        blink-cmp = {
+          enable = true;
+          settings = {
+            keymap.preset = "default";   # C-space open, C-y confirm, C-n/C-p move
+            appearance.nerd_font_variant = "mono";
+            sources.default = [ "lsp" "path" "snippets" "buffer" ];
+            completion.documentation.auto_show = true;
+          };
+        };
+
+        # Fuzzy finder — files, live grep, open buffers (buffer switching lives
+        # here rather than a bufferline; see the S-h/S-l binds below too).
+        telescope.enable = true;
+
+        # File tree.
+        neo-tree.enable = true;
+
+        # Statusline, NvChad-ish blocks: powerline separators, one global bar,
+        # theme following the colorscheme.
+        lualine = {
+          enable = true;
+          settings.options = {
+            theme = "auto";
+            globalstatus = true;
+            section_separators = { left = ""; right = ""; };
+            component_separators = { left = ""; right = ""; };
+          };
+        };
+
+        # Inline colour swatches for #rrggbb / colour names.
+        colorizer.enable = true;
+
+        # Git signs in the gutter.
+        gitsigns.enable = true;
+
+        # Session persistence: auto-saves a session per project directory into XDG
+        # state, restorable later. <leader>S restores the current dir's session; a
+        # consumer wanting auto-restore on a bare `nvim` adds a VimEnter autocmd.
+        persistence.enable = true;
+
+        # Floating terminal toggled with Ctrl-\ (shares nvim's cwd). Try it; if
+        # a tiled foot next to nvim serves you better, drop this block.
+        toggleterm = {
+          enable = true;
+          settings = {
+            open_mapping = { __raw = "[[<c-\\>]]"; };
+            direction = "float";
+          };
+        };
+
+        # Popup of the pending keybinds after leader — a live, always-accurate
+        # cheatsheet. The group labels name each leader subtree so the popup reads
+        # by category; <leader>? opens the full list on demand (keymaps below).
+        which-key = {
+          enable = true;
+          settings.spec = [
+            { __unkeyed-1 = "<leader>f"; group = "Find (Telescope)"; }
+            { __unkeyed-1 = "<leader>d"; group = "Diagnostics"; }
+            { __unkeyed-1 = "<leader>b"; group = "Buffer"; }
+            { __unkeyed-1 = "<leader>c"; group = "Code"; }
+            { __unkeyed-1 = "<leader>r"; group = "Refactor"; }
+            { __unkeyed-1 = "<leader>s"; group = "Search"; }
+          ];
+        };
+      };
+
+      # Global (non-LSP) keymaps. Deliberately small — a starting point to grow.
+      keymaps = [
+        { mode = "n"; key = "<leader>w"; action = "<cmd>w<cr>"; options.desc = "Save"; }
+        { mode = "n"; key = "<leader>q"; action = "<cmd>q<cr>"; options.desc = "Quit window"; }
+        { mode = "n"; key = "<leader>Q"; action = "<cmd>qa<cr>"; options.desc = "Quit all (exit nvim)"; }
+        # Restore the saved session for the current directory (persistence.nvim).
+        { mode = "n"; key = "<leader>S"; action.__raw = "function() require('persistence').load() end"; options.desc = "Restore session"; }
+        { mode = "n"; key = "<leader>e"; action = "<cmd>Neotree toggle<cr>"; options.desc = "File tree"; }
+        { mode = "n"; key = "<Esc>"; action = "<cmd>nohlsearch<cr>"; }
+
+        # Telescope
+        { mode = "n"; key = "<leader>ff"; action = "<cmd>Telescope find_files<cr>"; options.desc = "Find files"; }
+        { mode = "n"; key = "<leader>fg"; action = "<cmd>Telescope live_grep<cr>"; options.desc = "Live grep"; }
+        { mode = "n"; key = "<leader>fb"; action = "<cmd>Telescope buffers<cr>"; options.desc = "Buffers"; }
+        { mode = "n"; key = "<leader>fh"; action = "<cmd>Telescope help_tags<cr>"; options.desc = "Help tags"; }
+
+        # LSP navigation via Telescope pickers (fuzzy + preview) for the
+        # many-result lookups; gd/gD stay direct jumps (plugins.lsp.keymaps above).
+        { mode = "n"; key = "gr"; action = "<cmd>Telescope lsp_references<cr>"; options.desc = "References"; }
+        { mode = "n"; key = "gi"; action = "<cmd>Telescope lsp_implementations<cr>"; options.desc = "Implementations"; }
+
+        # Buffer navigation (no bufferline: cycle with Shift-h/l, list via <leader>fb)
+        { mode = "n"; key = "<S-l>"; action = "<cmd>bnext<cr>"; options.desc = "Next buffer"; }
+        { mode = "n"; key = "<S-h>"; action = "<cmd>bprevious<cr>"; options.desc = "Prev buffer"; }
+        { mode = "n"; key = "<leader>bd"; action = "<cmd>bdelete<cr>"; options.desc = "Close buffer"; }
+
+        # Cheatsheet: <leader>? pops the full which-key list; <leader>sk fuzzy-
+        # searches every active mapping via Telescope (catches non-leader binds too).
+        { mode = "n"; key = "<leader>?"; action = "<cmd>WhichKey<cr>"; options.desc = "All keybinds (which-key)"; }
+        { mode = "n"; key = "<leader>sk"; action = "<cmd>Telescope keymaps<cr>"; options.desc = "Search keymaps"; }
+      ];
+
+      # persistence saves the window layout via :mksession, but neo-tree's special
+      # buffer doesn't serialise — a saved tree window restores as a blank split.
+      # Close neo-tree just before a session is written so the layout stays clean.
+      autoCmd = [
+        {
+          event = "User";
+          pattern = "PersistenceSavePre";
+          callback.__raw = ''function() pcall(vim.cmd, "Neotree close") end'';
+        }
+      ];
+    };
+  };
+}