feat: allow changing the Copilot model used (#373)

fixes #365

Author: AntoineGS

README.md

@@ -87,6 +87,7 @@ require('copilot').setup({
     ["."] = false,
   },
   copilot_node_command = 'node', -- Node.js version must be > 18.x
+  copilot_model = "",  -- Current LSP default is gpt-35-turbo, supports gpt-4o-copilot
   server_opts_overrides = {},
 })
 ```

lua/copilot/client.lua

@@ -234,6 +234,9 @@ local function prepare_client_config(overrides)
       end
     end,
     handlers = handlers,
+    init_options = {
+      copilotIntegrationId = "vscode-chat",
+    },
   }, overrides)
 end
 

lua/copilot/config.lua

@@ -41,6 +41,8 @@ local default_config = {
   auth_provider_url = nil,
   copilot_node_command = "node",
   server_opts_overrides = {},
+  ---@type string|nil
+  copilot_model = nil,
 }
 
 local mod = {

lua/copilot/util.lua

@@ -203,13 +203,20 @@ function M.get_editor_configuration()
     filetypes = vim.tbl_deep_extend("keep", filetypes, internal_filetypes)
   end
 
+  local copilot_model = conf.copilot_model ~= "" and conf.copilot_model or ""
+
   ---@type string[]
   local disabled_filetypes = vim.tbl_filter(function(ft)
     return filetypes[ft] == false
   end, vim.tbl_keys(filetypes))
   table.sort(disabled_filetypes)
 
   return {
+    github = {
+      copilot = {
+        selectedCompletionModel = copilot_model,
+      },
+    },
     enableAutoCompletions = not not (conf.panel.enabled or conf.suggestion.enabled),
     disabledLanguages = vim.tbl_map(function(ft)
       return { languageId = ft }