# Task ID: 31

**Title:** Add DeepSeek API LLM provider

**Status:** done

**Dependencies:** 25 ✓

**Priority:** medium

**Description:** Implement DeepSeek API provider as a cheap cloud-based fallback when local LLMs are unavailable.

**Details:**

1. Create `src/mcplocal/src/providers/deepseek.ts`:
   ```typescript
   export class DeepSeekProvider implements LlmProvider {
     readonly name = 'deepseek';
     private apiKey: string;
     private baseUrl = 'https://api.deepseek.com/v1';
     
     constructor(config: DeepSeekConfig) {
       this.apiKey = config.apiKey || process.env.DEEPSEEK_API_KEY;
     }
     
     async isAvailable(): Promise<boolean> {
       return !!this.apiKey;
     }
     
     async complete(options: CompletionOptions): Promise<CompletionResult> {
       // DeepSeek uses OpenAI-compatible API
       const response = await fetch(`${this.baseUrl}/chat/completions`, {
         method: 'POST',
         headers: {
           'Authorization': `Bearer ${this.apiKey}`,
           'Content-Type': 'application/json'
         },
         body: JSON.stringify({
           model: 'deepseek-chat',
           messages: [{ role: 'user', content: options.userPrompt }]
         })
       });
       // Parse and return
     }
   }
   ```
2. Add DEEPSEEK_API_KEY to configuration
3. Register in provider registry with medium priority
4. Support both deepseek-chat and deepseek-coder models
5. Add rate limiting handling

**Test Strategy:**

1. Unit test: Provider correctly checks API key availability
2. Unit test: Request formatting matches DeepSeek API spec
3. Unit test: Response parsing handles all fields
4. Integration test: Full completion with actual API (with valid key)
5. Test error handling for rate limits
6. Test error handling for invalid API key