feat(ui): improve keyword highlights accuracy and performance (#1260)

Signed-off-by: Tomas Slusny <slusnucky@gmail.com>

Author: deathbeam

README.md

@@ -255,9 +255,13 @@ Types of copilot highlights:
 - `CopilotChatHeader` - Header highlight in chat buffer
 - `CopilotChatSeparator` - Separator highlight in chat buffer
 - `CopilotChatStatus` - Status and spinner in chat buffer
-- `CopilotChatHelp` - Help messages in chat buffer (help, references)
+- `CopilotChatHelp` - Help text in chat buffer
+- `CopilotChatResource` - Resource highlight in chat buffer (e.g. `#file`, `#gitdiff`)
+- `CopilotChatTool` - Tool call highlight in chat buffer (e.g. `@copilot`)
+- `CopilotChatPrompt` - Prompt highlight in chat buffer (e.g. `/Explain`, `/Review`)
+- `CopilotChatModel` - Model highlight in chat buffer (e.g. `$gpt-4.1`)
+- `CopilotChatUri` - URI highlight in chat buffer (e.g. `##https://...`)
 - `CopilotChatSelection` - Selection highlight in source buffer
-- `CopilotChatKeyword` - Keyword highlight in chat buffer (e.g. prompts, tools)
 - `CopilotChatAnnotation` - Annotation highlight in chat buffer (file headers, tool call headers, tool call body)
 
 ## Prompts

lua/CopilotChat/ui/chat.lua

@@ -340,6 +340,9 @@ function Chat:open(config)
     vim.wo[self.winnr].foldcolumn = '0'
   end
 
+  local ns = vim.api.nvim_create_namespace('copilot-chat-local-hl')
+  vim.api.nvim_set_hl(ns, '@markup.quote.markdown', {})
+  vim.api.nvim_win_set_hl_ns(self.winnr, ns)
   vim.api.nvim_win_set_buf(self.winnr, self.bufnr)
   self:render()
 end
@@ -678,22 +681,6 @@ function Chat:render()
       end
     end
 
-    -- Keywords
-    if current_message and current_message.role == 'user' then
-      -- FIXME: This is not optimal, but i cant figure out how to do it better as treesitter keeps overriding it
-      local patterns = {
-        '()#?#[^ ]+()',
-        '()@[^ ]+()',
-        '()%$[^ ]+()',
-        '()/[^ ]+()',
-      }
-      for _, pattern in ipairs(patterns) do
-        for s, e in line:gmatch(pattern) do
-          vim.api.nvim_buf_add_highlight(self.bufnr, highlight_ns, 'CopilotChatKeyword', l - 1, s - 1, e - 1)
-        end
-      end
-    end
-
     -- If last line, finish last message
     if l == #lines and current_message then
       current_message.section.end_line = l

plugin/CopilotChat.lua

@@ -16,10 +16,14 @@ local function setup_highlights()
   vim.api.nvim_set_hl(0, 'CopilotChatSeparator', { link = '@punctuation.special.markdown', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatStatus', { link = 'DiagnosticHint', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatHelp', { link = 'DiagnosticInfo', default = true })
-  vim.api.nvim_set_hl(0, 'CopilotChatKeyword', { link = 'Keyword', default = true })
+  vim.api.nvim_set_hl(0, 'CopilotChatResource', { link = 'Constant', default = true })
+  vim.api.nvim_set_hl(0, 'CopilotChatTool', { link = 'Function', default = true })
+  vim.api.nvim_set_hl(0, 'CopilotChatPrompt', { link = 'Statement', default = true })
+  vim.api.nvim_set_hl(0, 'CopilotChatModel', { link = 'Type', default = true })
+  vim.api.nvim_set_hl(0, 'CopilotChatUri', { link = 'Underlined', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatSelection', { link = 'Visual', default = true })
-  vim.api.nvim_set_hl(0, 'CopilotChatAnnotation', { link = 'ColorColumn', default = true })
 
+  vim.api.nvim_set_hl(0, 'CopilotChatAnnotation', { link = 'ColorColumn', default = true })
   local fg = vim.api.nvim_get_hl(0, { name = 'CopilotChatStatus', link = false }).fg
   local bg = vim.api.nvim_get_hl(0, { name = 'CopilotChatAnnotation', link = false }).bg
   vim.api.nvim_set_hl(0, 'CopilotChatAnnotationHeader', { fg = fg, bg = bg })
@@ -75,6 +79,18 @@ vim.api.nvim_create_user_command('CopilotChatReset', function()
   chat.reset()
 end, { force = true })
 
+vim.api.nvim_create_autocmd('FileType', {
+  pattern = 'copilot-chat',
+  group = group,
+  callback = vim.schedule_wrap(function()
+    vim.cmd.syntax('match CopilotChatResource "#\\S\\+"')
+    vim.cmd.syntax('match CopilotChatTool "@\\S\\+"')
+    vim.cmd.syntax('match CopilotChatPrompt "/\\S\\+"')
+    vim.cmd.syntax('match CopilotChatModel "\\$\\S\\+"')
+    vim.cmd.syntax('match CopilotChatUri "##\\S\\+"')
+  end),
+})
+
 local function complete_load()
   local chat = require('CopilotChat')
   local options = vim.tbl_map(function(file)