refactor: simplify HTTP headers

Remove unnecessary HTTP headers and standardize header casing across the
codebase. This simplifies the header management by:

- Removing unused machine ID and session ID tracking
- Using consistent header casing (capitalized)
- Removing redundant version headers
- Simplifying authorization header format

These changes make the code more maintainable while preserving core
functionality.

Source: https://github.com/zed-industries/zed/blob/ad43bbbf5eda59eba65309735472e0be58b4f7dd/crates/copilot/src/copilot_chat.rs#L324

Author: deathbeam

lua/CopilotChat/client.lua

@@ -214,7 +214,6 @@ local Client = class(function(self, providers)
   self.current_job = nil
   self.expires_at = nil
   self.headers = nil
-  self.machineid = utils.machine_id()
 end)
 
 --- Authenticate with GitHub and get the required headers
@@ -229,8 +228,7 @@ function Client:authenticate(provider_name)
     notify.publish(notify.STATUS, 'Authenticating to provider ' .. provider_name)
 
     local token, expires_at = provider.get_token()
-    local sessionid = utils.uuid() .. tostring(math.floor(os.time() * 1000))
-    headers = provider.get_headers(token, sessionid, self.machineid)
+    headers = provider.get_headers(token)
     self.provider_cache[provider_name].headers = headers
     self.provider_cache[provider_name].expires_at = expires_at
   end

lua/CopilotChat/config/providers.lua

@@ -17,7 +17,7 @@ local utils = require('CopilotChat.utils')
 ---@class CopilotChat.Provider
 ---@field disabled nil|boolean
 ---@field embeddings nil|string
----@field get_headers fun(token:string, sessionid:string, machineid:string):table<string, string>
+---@field get_headers fun(token:string):table<string, string>
 ---@field get_token fun():string,number?
 ---@field get_agents nil|fun(headers:table):table<CopilotChat.Provider.agent>
 ---@field get_models nil|fun(headers:table):table<CopilotChat.Provider.model>
@@ -31,16 +31,6 @@ local EDITOR_VERSION = 'Neovim/'
   .. '.'
   .. vim.version().patch
 
-local VERSION_HEADERS = {
-  ['editor-version'] = EDITOR_VERSION,
-  ['editor-plugin-version'] = 'CopilotChat.nvim/2.0.0',
-  ['user-agent'] = 'CopilotChat.nvim/2.0.0',
-  ['sec-fetch-site'] = 'none',
-  ['sec-fetch-mode'] = 'no-cors',
-  ['sec-fetch-dest'] = 'empty',
-  ['priority'] = 'u=4, i',
-}
-
 --- Get the github oauth cached token
 ---@return string|nil
 local cached_github_token = nil
@@ -92,25 +82,21 @@ local M = {}
 M.copilot = {
   embeddings = 'copilot_embeddings',
 
-  get_headers = function(token, sessionid, machineid)
-    return vim.tbl_extend('force', {
-      ['authorization'] = 'Bearer ' .. token,
-      ['x-request-id'] = utils.uuid(),
-      ['vscode-sessionid'] = sessionid,
-      ['vscode-machineid'] = machineid,
-      ['copilot-integration-id'] = 'vscode-chat',
-      ['openai-organization'] = 'github-copilot',
-      ['openai-intent'] = 'conversation-panel',
-      ['content-type'] = 'application/json',
-    }, VERSION_HEADERS)
+  get_headers = function(token)
+    return {
+      ['Authorization'] = 'Bearer ' .. token,
+      ['Editor-Version'] = EDITOR_VERSION,
+      ['Copilot-Integration-Id'] = 'vscode-chat',
+      ['Content-Type'] = 'application/json',
+    }
   end,
 
   get_token = function()
     local response, err = utils.curl_get('https://api.github.com/copilot_internal/v2/token', {
-      headers = vim.tbl_extend('force', {
-        ['authorization'] = 'token ' .. get_github_token(),
-        ['accept'] = 'application/json',
-      }, VERSION_HEADERS),
+      headers = {
+        ['Authorization'] = 'Token ' .. get_github_token(),
+        ['Accept'] = 'application/json',
+      }
     })
 
     if err then
@@ -237,8 +223,8 @@ M.github_models = {
 
   get_headers = function(token)
     return {
-      ['authorization'] = 'bearer ' .. token,
-      ['content-type'] = 'application/json',
+      ['Authorization'] = 'Bearer ' .. token,
+      ['Content-Type'] = 'application/json',
       ['x-ms-useragent'] = EDITOR_VERSION,
       ['x-ms-user-agent'] = EDITOR_VERSION,
     }