feat(copilot-chat): enhanced rendering of the chat window

lua/lazyvim/plugins/extras/coding/copilot-chat.lua

@@ -3,10 +3,16 @@ return {
     "CopilotC-Nvim/CopilotChat.nvim",
     branch = "canary",
     cmd = "CopilotChat",
-    opts = {
+    opts = function()
+      local user = vim.env.USER or "User"
+      user = user:sub(1, 1):upper() .. user:sub(2)
+      return {
         model = "gpt-4",
         auto_insert_mode = true,
         show_help = true,
+        question_header = "  " .. user .. " ",
+        answer_header = "  Copilot ",
+        separator = "---",
         window = {
           width = 0.4,
         },
@@ -14,7 +20,8 @@ return {
           local select = require("CopilotChat.select")
           return select.visual(source) or select.buffer(source)
         end,
-    },
+      }
+    end,
     keys = {
       {
         "<leader>aa",
@@ -53,13 +60,40 @@ return {
     end,
     config = function(_, opts)
       local chat = require("CopilotChat")
+      local ns = vim.api.nvim_create_namespace("copilot-chat-text-hl")
+
       vim.api.nvim_create_autocmd("BufEnter", {
         pattern = "copilot-chat",
-        callback = function()
+        callback = function(ev)
           vim.opt_local.relativenumber = false
           vim.opt_local.number = false
+
+          vim.api.nvim_create_autocmd({ "TextChanged", "TextChangedI" }, {
+            group = vim.api.nvim_create_augroup("copilot-chat-text-" .. ev.buf, { clear = true }),
+            buffer = ev.buf,
+            callback = function()
+              vim.api.nvim_buf_clear_namespace(ev.buf, ns, 0, -1)
+              local lines = vim.api.nvim_buf_get_lines(ev.buf, 0, -1, false)
+              for l, line in ipairs(lines) do
+                if line:match(opts.separator .. "$") then
+                  local sep = vim.fn.strwidth(line) - vim.fn.strwidth(opts.separator)
+                  vim.api.nvim_buf_set_extmark(ev.buf, ns, l - 1, sep, {
+                    virt_text_win_col = sep,
+                    virt_text = { { string.rep("─", vim.go.columns), "@punctuation.special.markdown" } },
+                    priority = 100,
+                  })
+                  vim.api.nvim_buf_set_extmark(ev.buf, ns, l - 1, 0, {
+                    end_col = sep + 1,
+                    hl_group = "@markup.heading.2.markdown",
+                    priority = 100,
+                  })
+                end
+              end
             end,
           })
+        end,
+      })
+
       chat.setup(opts)
     end,
   },