diff --git a/lazy-lock.json b/lazy-lock.json
new file mode 100644
index 0000000..f403e7c
--- /dev/null
+++ b/lazy-lock.json
@@ -0,0 +1,28 @@
+{
+  "LuaSnip": { "branch": "master", "commit": "642b0c595e11608b4c18219e93b88d7637af27bc" },
+  "autoclose.nvim": { "branch": "main", "commit": "bafd0368716216fa6a7bb2a43ecd889b44efdb46" },
+  "base16-vim": { "branch": "master", "commit": "3be3cd82cd31acfcab9a41bad853d9c68d30478d" },
+  "bitcoin-script-hints.nvim": { "branch": "main", "commit": "628badbb09a230e3838d863b21dcc07cdd2429bc" },
+  "bufferline.nvim": { "branch": "main", "commit": "655133c3b4c3e5e05ec549b9f8cc2894ac6f51b3" },
+  "cmp-nvim-lsp": { "branch": "main", "commit": "cbc7b02bb99fae35cb42f514762b89b5126651ef" },
+  "cmp_luasnip": { "branch": "master", "commit": "98d9cb5c2c38532bd9bdb481067b20fea8f32e90" },
+  "gitsigns.nvim": { "branch": "main", "commit": "6d808f99bd63303646794406e270bd553ad7792e" },
+  "indent-blankline.nvim": { "branch": "master", "commit": "d28a3f70721c79e3c5f6693057ae929f3d9c0a03" },
+  "lazy.nvim": { "branch": "main", "commit": "306a05526ada86a7b30af95c5cc81ffba93fef97" },
+  "log-highlight.nvim": { "branch": "main", "commit": "ca88628f6dd3b9bb46f9a7401669e24cf7de47a4" },
+  "lualine.nvim": { "branch": "master", "commit": "131a558e13f9f28b15cd235557150ccb23f89286" },
+  "mason-lspconfig.nvim": { "branch": "main", "commit": "0c2823e0418f3d9230ff8b201c976e84de1cb401" },
+  "mason.nvim": { "branch": "main", "commit": "cb8445f8ce85d957416c106b780efd51c6298f89" },
+  "neo-tree.nvim": { "branch": "main", "commit": "19d20a99bf0061a5ecc4343d2f09fa713306c965" },
+  "nui.nvim": { "branch": "main", "commit": "de740991c12411b663994b2860f1a4fd0937c130" },
+  "nvim-cmp": { "branch": "main", "commit": "a1d504892f2bc56c2e79b65c6faded2fd21f3eca" },
+  "nvim-lspconfig": { "branch": "master", "commit": "f7e89f3d19fb436e1fbeff3bf4291eef35da94e3" },
+  "nvim-navic": { "branch": "master", "commit": "f5eba192f39b453675d115351808bd51276d9de5" },
+  "nvim-treesitter": { "branch": "main", "commit": "df7489eeea351bece7fd0f9c825be5cb6a1438f0" },
+  "nvim-web-devicons": { "branch": "master", "commit": "4fc505ac7bd7692824a142e96e5f529c133862f8" },
+  "plenary.nvim": { "branch": "master", "commit": "74b06c6c75e4eeb3108ec01852001636d85a932b" },
+  "telescope.nvim": { "branch": "0.1.x", "commit": "a0bbec21143c7bc5f8bb02e0005fa0b982edc026" },
+  "todo-comments.nvim": { "branch": "main", "commit": "31e3c38ce9b29781e4422fc0322eb0a21f4e8668" },
+  "treesitter-parser-registry": { "branch": "main", "commit": "6eb15358bb9fc88f0d3401d8538d56652e9bdf3c" },
+  "which-key.nvim": { "branch": "main", "commit": "3aab2147e74890957785941f0c1ad87d0a44c15a" }
+}
diff --git a/lua/plugins/disabled.lua b/lua/plugins/disabled.lua
index 64e75ec..0b7a483 100644
--- a/lua/plugins/disabled.lua
+++ b/lua/plugins/disabled.lua
@@ -1,5 +1,3 @@
 return {
-	{ "williamboman/mason.nvim", enabled = false },
-	{ "williamboman/mason-lspconfig.nvim", enabled = false },
 	{ "jay-babu/mason-nvim-dap.nvim", enabled = false },
 }
diff --git a/lua/plugins/lsp.lua b/lua/plugins/lsp.lua
index c31339b..3372cff 100644
--- a/lua/plugins/lsp.lua
+++ b/lua/plugins/lsp.lua
@@ -1,11 +1,7 @@
 -- Neovim 0.11+ LSP configuration
 -- Uses nvim-lspconfig for server definitions + vim.lsp.enable() API
 
--- Detect NixOS (Mason doesn't work on NixOS due to FHS issues)
-local is_nixos = vim.fn.filereadable("/etc/NIXOS") == 1
-
--- Servers to ensure are installed via Mason (non-NixOS only)
--- On NixOS, install these via extraPackages or per-project devShells
+-- Servers to ensure are installed via Mason.
 local mason_ensure_installed = {
   "lua_ls",       -- Neovim config
   "nil_ls",       -- Nix (nixd not available in Mason)
@@ -18,13 +14,43 @@ local mason_ensure_installed = {
   "yamlls",       -- YAML
 }
 
+local treesitter_parsers = {
+  "lua",
+  "c",
+  "cpp",
+  "python",
+  "nix",
+  "rust",
+  "bash",
+  "markdown",
+  "html",
+  "html_tags",
+  "javascript",
+  "ecma",
+  "jsx",
+  "css",
+  "vim",
+  "git_config",
+  "git_rebase",
+  "gitattributes",
+  "gitcommit",
+  "gitignore",
+}
+
 return {
   {
-    "nvim-treesitter/nvim-treesitter",
+    "neovim-treesitter/nvim-treesitter",
+    name = "nvim-treesitter",
+    dependencies = {
+      "neovim-treesitter/treesitter-parser-registry",
+      "williamboman/mason.nvim",
+    },
+    lazy = false,
     build = ":TSUpdate",
-    config = function()
-      require('nvim-treesitter.configs').setup({
-        ensure_installed = {
+    init = function()
+      vim.api.nvim_create_autocmd("FileType", {
+        group = vim.api.nvim_create_augroup("config_treesitter", { clear = true }),
+        pattern = {
           "lua",
           "c",
           "cpp",
@@ -35,22 +61,133 @@ return {
           "markdown",
           "html",
           "javascript",
+          "javascriptreact",
           "css",
-
           "vim",
-
-          "git_config",
-          "git_rebase",
+          "gitconfig",
+          "gitrebase",
           "gitattributes",
           "gitcommit",
-          "gitignore"
+          "gitignore",
         },
-        auto_install = true,
-        sync_install = true,
-        highlight = {
-          enable = true,
-        }
+        callback = function(event)
+          if pcall(vim.treesitter.start, event.buf) then
+            vim.bo[event.buf].indentexpr = "v:lua.require'nvim-treesitter'.indentexpr()"
+          end
+        end,
       })
+    end,
+    config = function()
+      require("nvim-treesitter").setup()
+
+      local function has_c_compiler()
+        return vim.fn.executable("cc") == 1
+          or vim.fn.executable("gcc") == 1
+          or vim.fn.executable("clang") == 1
+      end
+
+      local function install_missing_parsers(missing)
+        if not has_c_compiler() then
+          vim.notify_once(
+            "A C compiler is required to install or update Treesitter parsers",
+            vim.log.levels.WARN
+          )
+          return
+        end
+
+        require("nvim-treesitter").install(missing)
+      end
+
+      local function tree_sitter_cli_works()
+        if vim.fn.executable("tree-sitter") == 0 then
+          return false
+        end
+
+        local result = vim.system({ "tree-sitter", "--version" }, { text = true }):wait()
+        if result.code == 0 then
+          return true
+        end
+
+        vim.notify_once(
+          "tree-sitter CLI is installed but cannot run. On NixOS, enable nix-ld so Mason-installed binaries can execute.",
+          vim.log.levels.WARN
+        )
+        return false
+      end
+
+      local function ensure_treesitter_cli(callback)
+        if tree_sitter_cli_works() then
+          callback()
+          return
+        end
+
+        if #vim.api.nvim_list_uis() == 0 then
+          return
+        end
+
+        local mason_ok, mason = pcall(require, "mason")
+        local registry_ok, registry = pcall(require, "mason-registry")
+        if not mason_ok or not registry_ok then
+          vim.notify_once(
+            "tree-sitter CLI is required to install or update parsers; install tree-sitter-cli or enable mason.nvim",
+            vim.log.levels.WARN
+          )
+          return
+        end
+
+        mason.setup()
+        registry.refresh(function()
+          local package_ok, package = pcall(registry.get_package, "tree-sitter-cli")
+          if not package_ok then
+            vim.notify_once(
+              "Mason registry does not include tree-sitter-cli; install tree-sitter-cli before running :TSUpdate",
+              vim.log.levels.WARN
+            )
+            return
+          end
+
+          if package:is_installed() then
+            if tree_sitter_cli_works() then
+              callback()
+            end
+            return
+          end
+
+          if package:is_installing() then
+            vim.notify_once("tree-sitter-cli is already being installed by Mason", vim.log.levels.INFO)
+            return
+          end
+
+          vim.notify_once("Installing tree-sitter-cli with Mason for Treesitter parser updates", vim.log.levels.INFO)
+          package:install({}, function(success, error)
+            if success and tree_sitter_cli_works() then
+              callback()
+            else
+              vim.notify(
+                "Failed to install tree-sitter-cli with Mason: " .. tostring(error),
+                vim.log.levels.WARN
+              )
+            end
+          end)
+        end)
+      end
+
+      local installed = require("nvim-treesitter.config").get_installed()
+      local missing = vim.iter(treesitter_parsers)
+          :filter(function(parser)
+            return not vim.tbl_contains(installed, parser)
+          end)
+          :totable()
+
+      if #missing == 0 and #vim.api.nvim_list_uis() == 0 then
+        return
+      end
+
+      ensure_treesitter_cli(function()
+        if #missing > 0 then
+          install_missing_parsers(missing)
+        end
+      end)
     end
   },
 
@@ -113,17 +250,16 @@ return {
     end
   },
 
-  -- Mason: portable LSP installer (disabled on NixOS where it doesn't work)
+  -- Mason: portable LSP installer. On NixOS this requires nix-ld for
+  -- downloaded Linux binaries to run.
   {
     "williamboman/mason.nvim",
-    enabled = not is_nixos,
     config = function()
       require("mason").setup()
     end
   },
   {
     "williamboman/mason-lspconfig.nvim",
-    enabled = not is_nixos,
     dependencies = { "williamboman/mason.nvim" },
     config = function()
       require("mason-lspconfig").setup({
@@ -302,7 +438,7 @@ return {
 
   {
     "taproot-wizards/bitcoin-script-hints.nvim",
-    dependencies = { "nvim-treesitter/nvim-treesitter" },
+    dependencies = { "nvim-treesitter" },
     config = function()
       require("bitcoin-script-hints").setup()
     end