AI Module

protocol LLMClient: Sendable {
    func streamResponse(
        messages: [LLMMessage],
        model: String?,
        temperature: Double?
    ) -> AsyncThrowingStream<String, Error>
}

// Environment-gated client selection
private func createLLMClient(httpClient: HTTPClient) -> LLMClient {
    let env = ProcessInfo.processInfo.environment
    let proxyBaseURL = env["PROXY_BASE_URL"]
    
    // If no proxy URL → use Echo client (testing)
    guard let baseURLString = proxyBaseURL,
          let baseURL = URL(string: baseURLString) else {
        AppLogger.info("LLM provider: EchoLLMClient", category: AppLogger.ai)
        return EchoLLMClient()
    }
    
    // Parse configuration
    let proxyPath = env["PROXY_PATH"] ?? "/v1/chat/stream"
    
    // Create production proxy client
    let proxyClient = ProxyLLMClient(
        baseURL: baseURL,
        httpClient: httpClient,  // Uses AuthInterceptor automatically
        path: proxyPath,
        defaultHeaders: [:]
    )
    
    AppLogger.info("LLM provider: ProxyLLMClient", category: AppLogger.ai)
    return proxyClient
}

// Usage in composition
self.llmClient = createLLMClient(httpClient: httpClient)

// In ViewModel
for try await chunk in llmClient.streamResponse(messages: messages) {
    // Update UI with each token
    currentResponse += chunk
}

// supabase/functions/ai/index.ts
Deno.serve(async (req) => {
  // 1. Verify user auth
  // 2. Extract messages from request
  // 3. Call OpenRouter with server-side key
  // 4. Stream response back to client
})

supabase secrets set OPENROUTER_API_KEY=sk-or-v1-YOUR_KEY
supabase functions deploy ai

// In ChatViewModel or per-conversation
let stream = llmClient.streamResponse(
    messages: messages,
    model: "anthropic/claude-3-5-sonnet",  // Change model
    temperature: 0.7
)

// Add persona to conversation
let systemMessage = LLMMessage(
    role: .system,
    content: """
    You are a professional Swift developer.
    Provide clear, concise answers with code examples.
    """
)

let messages = [systemMessage] + conversationHistory + [userMessage]

// Want to call OpenAI directly?
class OpenAIClient: LLMClient {
    func streamResponse(messages: [LLMMessage]) 
        -> AsyncThrowingStream<String, Error> 
    {
        // Direct OpenAI API integration
        // No proxy needed
    }
}

// Update CompositionRoot
self.llmClient = OpenAIClient(apiKey: ...)