nvim: edit chezmoi source files in their underlying language

dot_config/nvim/lua/autocmds.lua

@@ -5,6 +5,19 @@ end
 -- Filetype detection
 vim.filetype.add({ extension = { j2 = "jinja.html" } })
 
+-- chezmoi templates: alker0/chezmoi.vim sets a compound `<base>.chezmoitmpl`
+-- filetype and owns highlighting via merged base+go-template vim-syntax. Stop
+-- treesitter (avoids a double-highlight conflict) and silence diagnostics so the
+-- {{ }} regions aren't redlined as invalid base-language syntax.
+vim.api.nvim_create_autocmd("FileType", {
+  group = augroup("chezmoi_templates"),
+  pattern = "*chezmoitmpl*",
+  callback = function(event)
+    pcall(vim.treesitter.stop, event.buf)
+    vim.diagnostic.enable(false, { bufnr = event.buf })
+  end,
+})
+
 -- Highlight on yank
 vim.api.nvim_create_autocmd("TextYankPost", {
   group = augroup("yank_highlight"),

dot_config/nvim/lua/plugins/chezmoi.lua

@@ -0,0 +1,20 @@
+-- Editing chezmoi source files (dot_*, *.tmpl) in their *underlying* language.
+-- alker0/chezmoi.vim detects managed files under the source dir, resolves the
+-- chezmoi naming (dot_foo → .foo) and the `.tmpl` suffix, sets the base
+-- filetype, and merges go-template syntax over the {{ }} regions.
+--
+-- Pairs with:
+--   • conform `.tmpl` skip (plugins/editing.lua) — formatters never corrupt templates
+--   • the `chezmoitmpl` FileType guard (autocmds.lua) — stops treesitter highlight
+--     (the plugin's vim-syntax owns templates) and silences {{ }} diagnostics
+return {
+  {
+    "alker0/chezmoi.vim",
+    lazy = false, -- detection hooks must register before any source file opens
+    init = function()
+      -- required for reliable filetype detection under lazy.nvim
+      vim.g["chezmoi#use_tmp_buffer"] = true
+      vim.g["chezmoi#source_dir_path"] = vim.fn.expand("~/.local/share/chezmoi")
+    end,
+  },
+}

dot_config/nvim/lua/plugins/editing.lua

@@ -74,10 +74,14 @@ return {
           end,
         },
       },
-      format_on_save = {
-        timeout_ms = 2000,
-        lsp_fallback = true,
-      },
+      format_on_save = function(bufnr)
+        -- Never run formatters on chezmoi templates: stylua/prettier/taplo would
+        -- choke on the {{ }} go-template syntax and corrupt the source file.
+        if vim.api.nvim_buf_get_name(bufnr):match("%.tmpl$") then
+          return
+        end
+        return { timeout_ms = 2000, lsp_fallback = true }
+      end,
     },
   },