The next wave is to create lots of AI agents. So far the most successful ones are cursor and windsurf, the non-commercial part of windsurf is Codeium’s plugin for Vim, open sourced on github, let’s break it down and see if we can create such cool product too.

under the autoload folder, there is the vim file

function! codeium#command#BrowserCommand() abort
  if has('win32') && executable('rundll32')
    return 'rundll32 url.dll,FileProtocolHandler'
  elseif isdirectory('/private') && executable('/usr/bin/open')
    return '/usr/bin/open'
  elseif executable('xdg-open')
    return 'xdg-open'
  else
    return ''
  endif
endfunction

function! codeium#command#XdgConfigDir() abort
  let config_dir = $XDG_CONFIG_HOME
  if empty(config_dir)
    let config_dir = $HOME . '/.config'
  endif
  return config_dir . '/codeium'
endfunction

function! codeium#command#HomeDir() abort
  let data_dir = $XDG_DATA_HOME
  if empty(data_dir)
    let data_dir = $HOME . '/.codeium'
  else
    let data_dir = data_dir . '/.codeium'
  endif
  return data_dir
endfunction

function! codeium#command#LoadConfig(dir) abort
  let config_path = a:dir . '/config.json'
  if filereadable(config_path)
    let contents = join(readfile(config_path), '')
    if !empty(contents)
      return json_decode(contents)
    endif
  endif

  return {}
endfunction

let s:api_key = get(codeium#command#LoadConfig(codeium#command#HomeDir()), 'apiKey', '')

let s:commands = {}

function! s:commands.Auth(...) abort
  if !codeium#util#HasSupportedVersion()
    if has('nvim')
      let min_version = 'NeoVim 0.6'
    else
      let min_version = 'Vim 9.0.0185'
    endif
    echoerr 'This version of Vim is unsupported. Install ' . min_version . ' or greater to use Codeium.'
    return
  endif

  let config = get(g:, 'codeium_server_config', {})
  let portal_url = get(config, 'portal_url', 'https://www.codeium.com')

  let url = portal_url . '/profile?response_type=token&redirect_uri=vim-show-auth-token&state=a&scope=openid%20profile%20email&redirect_parameters_type=query'
  let browser = codeium#command#BrowserCommand()
  let opened_browser = v:false
  if !empty(browser)
    echomsg 'Navigating to ' . url
    try
      call system(browser . ' ' . '"' . url . '"')
      if v:shell_error is# 0
        let opened_browser = v:true
      endif
    catch
    endtry

    if !opened_browser
      echomsg 'Failed to open browser. Please go to the link above.'
    endif
  else
    echomsg 'No available browser found. Please go to ' . url
  endif

  let api_key = ''
  call inputsave()
  let auth_token = inputsecret('Paste your token here: ')
  call inputrestore()
  let tries = 0

  if has_key(config, 'api_url') && !empty(config.api_url)
    let register_user_url = config.api_url . '/exa.seat_management_pb.SeatManagementService/RegisterUser'
  else
    let register_user_url = 'https://api.codeium.com/register_user/'
  endif

  while empty(api_key) && tries < 3
    let command = 'curl -sS ' . register_user_url . ' ' .
          \ '--header "Content-Type: application/json" ' .
          \ '--data ' . shellescape(json_encode({'firebase_id_token': auth_token}))
    let response = system(command)
    let curl_ssl_error = 'The revocation function was unable to check revocation '
          \ . 'for the certificate.'
    if has('win32') && response=~curl_ssl_error
        call inputsave()
        let useNoSsl = input('For Windows systems behind a corporate proxy there '
              \ . 'may be trouble verifying the SSL certificates. '
              \ . 'Would you like to try auth without checking SSL certificate revocation? (y/n): ')
        call inputrestore()
        if useNoSsl ==? 'y'
            let command = 'curl --ssl-no-revoke -sS ' . register_user_url . ' ' .
                  \ '--header "Content-Type: application/json" ' .
                  \ '--data ' . shellescape(json_encode({'firebase_id_token': auth_token}))
            let response = system(command)
        endif
    endif
    let res = json_decode(response)
    let api_key = get(res, 'api_key', '')
    if empty(api_key)
      echomsg 'Unexpected response: ' . response
      call inputsave()
      let auth_token = inputsecret('Invalid token, please try again: ')
      call inputrestore()
    endif
    let tries = tries + 1
  endwhile

  if !empty(api_key)
    let s:api_key = api_key
    let config_dir = codeium#command#HomeDir()
    let config_path = config_dir . '/config.json'
    let config = codeium#command#LoadConfig(config_dir)
    let config.apiKey = api_key

    try
      call mkdir(config_dir, 'p')
      call writefile([json_encode(config)], config_path)
    catch
      call codeium#log#Error('Could not persist api key to config.json')
    endtry
  endif
endfunction

function s:commands.Chat(...) abort
  call codeium#Chat()
endfunction

function! s:commands.Disable(...) abort
  let g:codeium_enabled = 0
endfunction

function! s:commands.DisableBuffer(...) abort
  let b:codeium_enabled = 0
endfunction

" Run codeium server only if its not already started
function! codeium#command#StartLanguageServer() abort
  if !get(g:, 'codeium_server_started', v:false)
    call timer_start(0, function('codeium#server#Start'))
    let g:codeium_server_started = v:true
  endif
endfunction

function! s:commands.Enable(...) abort
  let g:codeium_enabled = 1
  call codeium#command#StartLanguageServer()
endfunction

function! s:commands.EnableBuffer(...) abort
  let b:codeium_enabled = 1
  call codeium#command#StartLanguageServer()
endfunction

function! s:commands.Toggle(...) abort
  if exists('g:codeium_enabled') && g:codeium_enabled == v:false
      call s:commands.Enable()
  else
      call s:commands.Disable()
  endif
endfunction

function! codeium#command#ApiKey() abort
  if s:api_key == ''
    echom 'Codeium: No API key found; maybe you need to run `:Codeium Auth`?'
  endif
  return s:api_key
endfunction

function! codeium#command#Complete(arg, lead, pos) abort
  let args = matchstr(strpart(a:lead, 0, a:pos), 'C\%[odeium][! ] *\zs.*')
  return sort(filter(keys(s:commands), { k -> strpart(k, 0, len(a:arg)) ==# a:arg }))
endfunction

function! codeium#command#Command(arg) abort
  let cmd = matchstr(a:arg, '^\%(\\.\|\S\)\+')
  let arg = matchstr(a:arg, '\s\zs\S.*')
  if !has_key(s:commands, cmd)
    return 'echoerr ' . string("Codeium: command '" . string(cmd) . "' not found")
  endif
  let res = s:commands[cmd](arg)
  if type(res) == v:t_string
    return res
  else
    return ''
  endif
endfunction

This Vim script defines several functions and commands for the Codeium plugin, which provides AI-powered code completion; sets up the core functionality for Codeium, handling authentication, configuration, and basic commands for enabling/disabling the plugin globally or per buffer.

language server architecture, where a compiled executable binary is downloaded and installed on the user’s machine2. This language server communicates with Codeium’s API at https://server.codeium.com, but the server-side code itself is not open source.

While it’s true that Codeium and similar services use various language models, including some publicly available ones like GPT-4, the real value and “secret sauce” of these code completion tools lies in several key aspects beyond just calling LLMs:

Proprietary Components

1. Context Engine: Codeium has developed a proprietary context engine that builds a deep understanding of codebases3. This engine uses advanced retrieval-augmented generation (RAG) techniques to construct highly relevant, context-rich prompts for the LLMs.
2. Custom Language Models: Codeium has trained its own proprietary language models specifically tailored for code completion tasks12.

Advanced Techniques

1. Optimized RAG Approach: The Codeium team has implemented a highly optimized RAG approach for codebase context, which has proven effective in producing high-quality suggestions with few hallucinations3.
2. Indexing and Retrieval: Codeium indexes local and remote codebases, using sophisticated retrieval methods to source relevant code snippets as users write code or ask questions3.

Integration and User Experience

1. IDE Integration: The seamless integration with various IDEs and the user-friendly interface are crucial parts of the product that go beyond just calling LLMs2.
2. Performance Optimization: These services have optimized their systems for real-time code completion, which requires careful engineering to maintain low latency and high accuracy.

The secrecy around the server code is likely due to these proprietary components and optimizations, which represent significant intellectual property and competitive advantages for companies like Codeium. While the use of public LLMs is part of their stack, the real value lies in how they process, contextualize, and deliver the results to users in an efficient and accurate manner.

for example, a crude context engine in Python. This example will demonstrate a simple approach to building context for code completion tasks:

import re
from collections import defaultdict

class SimpleContextEngine:
    def __init__(self):
        self.code_snippets = []
        self.function_index = defaultdict(list)
        self.variable_index = defaultdict(list)

    def add_code_snippet(self, snippet):
        snippet_id = len(self.code_snippets)
        self.code_snippets.append(snippet)
        
        # Index functions
        functions = re.findall(r'def\s+(\w+)', snippet)
        for func in functions:
            self.function_index[func].append(snippet_id)
        
        # Index variables
        variables = re.findall(r'\b(\w+)\s*=', snippet)
        for var in variables:
            self.variable_index[var].append(snippet_id)

    def get_context(self, current_code, max_snippets=3):
        context = []
        
        # Find relevant functions
        functions = re.findall(r'\b(\w+)\(', current_code)
        for func in functions:
            for snippet_id in self.function_index[func][:max_snippets]:
                context.append(self.code_snippets[snippet_id])
        
        # Find relevant variables
        variables = re.findall(r'\b(\w+)\b', current_code)
        for var in variables:
            for snippet_id in self.variable_index[var][:max_snippets]:
                if self.code_snippets[snippet_id] not in context:
                    context.append(self.code_snippets[snippet_id])
        
        return "\n".join(context[:max_snippets])

# Example usage
engine = SimpleContextEngine()

# Add some code snippets to the engine
engine.add_code_snippet("""
def calculate_area(radius):
    return 3.14 * radius ** 2
""")

engine.add_code_snippet("""
def greet(name):
    return f"Hello, {name}!"
""")

engine.add_code_snippet("""
user_name = "Alice"
greeting = greet(user_name)
print(greeting)
""")

# Get context for a current code snippet
current_code = "radius = 5\narea = calculate_area(radius)"
context = engine.get_context(current_code)
print("Context:")
print(context)

# Use this context with an LLM for code completion
# (LLM integration not included in this example)