refactor: replace plenary scheduler with internal implementation

Remove dependency on plenary.async.util.scheduler() by implementing a
custom schedule_main() function that only schedules when necessary.
This allows the plugin to work without requiring plenary's scheduling
mechanism. Also fixes JSON decoding by ensuring response body is
properly converted to string.

lua/CopilotChat/config/contexts.lua

@@ -1,4 +1,3 @@
-local async = require('plenary.async')
 local context = require('CopilotChat.context')
 local utils = require('CopilotChat.utils')
 
@@ -63,7 +62,7 @@ return {
         max_files = 1000,
       })
 
-      async.util.scheduler()
+      utils.schedule_main()
       vim.ui.select(files, {
         prompt = 'Select a file> ',
       }, callback)

lua/CopilotChat/config/mappings.lua

@@ -354,7 +354,7 @@ return {
         local _, selected_agent = pcall(copilot.resolve_agent, prompt, config)
         local _, selected_model = pcall(copilot.resolve_model, prompt, config)
 
-        async.util.scheduler()
+        utils.schedule_main()
         table.insert(lines, '**Logs**: `' .. chat.config.log_path .. '`')
         table.insert(lines, '**History**: `' .. chat.config.history_path .. '`')
         table.insert(lines, '**Temp Files**: `' .. vim.fn.fnamemodify(os.tmpname(), ':h') .. '`')
@@ -429,7 +429,7 @@ return {
           table.insert(lines, '')
         end
 
-        async.util.scheduler()
+        utils.schedule_main()
         overlay:show(vim.trim(table.concat(lines, '\n')) .. '\n', chat.winnr, 'markdown')
       end)
     end,

lua/CopilotChat/context.lua

@@ -412,7 +412,7 @@ function M.files(winnr, with_content, search_options)
 
   -- Read file contents
   if with_content then
-    async.util.scheduler()
+    utils.schedule_main()
 
     files = vim.tbl_filter(
       function(file)
@@ -445,7 +445,7 @@ function M.file(filename)
     return nil
   end
 
-  async.util.scheduler()
+  utils.schedule_main()
   local ft = utils.filetype(filename)
   if not ft then
     return nil
@@ -458,7 +458,7 @@ end
 ---@param bufnr number
 ---@return CopilotChat.context.embed?
 function M.buffer(bufnr)
-  async.util.scheduler()
+  utils.schedule_main()
 
   if not utils.buf_valid(bufnr) then
     return nil
@@ -483,7 +483,7 @@ end
 ---@param buf_type string
 ---@return table<CopilotChat.context.embed>
 function M.buffers(buf_type)
-  async.util.scheduler()
+  utils.schedule_main()
 
   return vim.tbl_map(
     M.buffer,
@@ -593,7 +593,7 @@ end
 ---@param register string
 ---@return CopilotChat.context.embed?
 function M.register(register)
-  async.util.scheduler()
+  utils.schedule_main()
 
   local lines = vim.fn.getreg(register)
   if not lines or lines == '' then
@@ -610,7 +610,7 @@ end
 --- Get the content of the quickfix list
 ---@return table<CopilotChat.context.embed>
 function M.quickfix()
-  async.util.scheduler()
+  utils.schedule_main()
 
   local items = vim.fn.getqflist()
   if not items or #items == 0 then

lua/CopilotChat/init.lua

@@ -496,7 +496,7 @@ function M.complete_items(callback)
       return a.kind < b.kind
     end)
 
-    async.util.scheduler()
+    utils.schedule_main()
     callback(items)
   end)
 end
@@ -577,7 +577,7 @@ function M.select_model()
       }
     end, models)
 
-    async.util.scheduler()
+    utils.schedule_main()
     vim.ui.select(choices, {
       prompt = 'Select a model> ',
       format_item = function(item)
@@ -608,7 +608,7 @@ function M.select_agent()
       }
     end, agents)
 
-    async.util.scheduler()
+    utils.schedule_main()
     vim.ui.select(choices, {
       prompt = 'Select an agent> ',
       format_item = function(item)
@@ -714,7 +714,7 @@ function M.ask(prompt, config)
       pcall(context.filter_embeddings, prompt, selected_model, config.headless, embeddings)
 
     if not query_ok then
-      async.util.scheduler()
+      utils.schedule_main()
       log.error(filtered_embeddings)
       if not config.headless then
         show_error(filtered_embeddings, has_output)
@@ -739,7 +739,7 @@ function M.ask(prompt, config)
         end),
       })
 
-    async.util.scheduler()
+    utils.schedule_main()
 
     if not ask_ok then
       log.error(response)
@@ -776,7 +776,7 @@ function M.ask(prompt, config)
   end)
 
   if not ok then
-    async.util.scheduler()
+    utils.schedule_main()
     log.error(err)
     if not config.headless then
       show_error(err)

lua/CopilotChat/tiktoken.lua

@@ -1,4 +1,3 @@
-local async = require('plenary.async')
 local notify = require('CopilotChat.notify')
 local utils = require('CopilotChat.utils')
 local current_tokenizer = nil
@@ -11,7 +10,7 @@ end
 --- Load tiktoken data from cache or download it
 ---@param tokenizer string The tokenizer to load
 local function load_tiktoken_data(tokenizer)
-  async.util.scheduler()
+  utils.schedule_main()
 
   local tiktoken_url = 'https://openaipublic.blob.core.windows.net/encodings/'
     .. tokenizer
@@ -57,7 +56,7 @@ M.load = function(tokenizer)
   local pat_str =
     "(?i:'s|'t|'re|'ve|'m|'ll|'d)|[^\\r\\n\\p{L}\\p{N}]?\\p{L}+|\\p{N}{1,3}| ?[^\\s\\p{L}\\p{N}]+[\\r\\n]*|\\s*[\\r\\n]+|\\s+(?!\\S)|\\s+"
 
-  async.util.scheduler()
+  utils.schedule_main()
   tiktoken_core.new(path, special_tokens, pat_str)
   current_tokenizer = tokenizer
 end

lua/CopilotChat/utils.lua

@@ -344,7 +344,7 @@ M.curl_get = async.wrap(function(url, opts, callback)
       return
     end
 
-    local body, err = M.json_decode(response.body)
+    local body, err = M.json_decode(tostring(response.body))
     if err then
       callback(response, err)
     else
@@ -388,7 +388,7 @@ M.curl_post = async.wrap(function(url, opts, callback)
       return
     end
 
-    local body, err = M.json_decode(response.body)
+    local body, err = M.json_decode(tostring(response.body))
     if err then
       callback(response, err)
     else
@@ -464,6 +464,20 @@ M.system = async.wrap(function(cmd, callback)
   vim.system(cmd, { text = true }, callback)
 end, 2)
 
+--- Schedule a function only when needed (not on main thread)
+---@param callback function The callback
+M.schedule_main = async.wrap(function(callback)
+  if vim.in_fast_event() then
+    -- In a fast event, need to schedule
+    vim.schedule(function()
+      callback()
+    end)
+  else
+    -- Already on main thread, call directly
+    callback()
+  end
+end, 1)
+
 --- Get the info for a key.
 ---@param name string
 ---@param surround string|nil