# Issue #122: Create LLM Provider Interface

## Objective

Define the abstract contract that all LLM providers (Ollama, Claude, OpenAI) must implement to enable multi-provider support.

## Approach

### Current State

- `LlmService` is hardcoded to Ollama
- Direct coupling to `ollama` npm package
- Methods: `chat()`, `chatStream()`, `embed()`, `listModels()`, `checkHealth()`

### Target Architecture

```
LlmProviderInterface (abstract)
  ├── OllamaProvider (implements)
  ├── ClaudeProvider (implements)
  └── OpenAIProvider (implements)

LlmManagerService
  └── manages provider instances
  └── routes requests to appropriate provider
```

### Interface Methods (from current LlmService)

1. `chat(request)` - Synchronous chat completion
2. `chatStream(request)` - Streaming chat completion (async generator)
3. `embed(request)` - Generate embeddings
4. `listModels()` - List available models
5. `checkHealth()` - Health check

### Provider Configuration

Each provider needs different config:

- Ollama: `{ host, timeout }`
- Claude: `{ apiKey, baseUrl?, timeout? }`
- OpenAI: `{ apiKey, baseUrl?, organization?, timeout? }`

Need generic config interface that providers can extend.

## Progress

- [x] Write interface tests (TDD - RED)
- [x] Create base types and DTOs
- [x] Implement LlmProviderInterface
- [x] Implement LlmProviderConfig interface
- [x] Add JSDoc documentation
- [x] Run tests (TDD - GREEN) - All 13 tests passed
- [x] Type checking passed
- [x] Refactor if needed (TDD - REFACTOR) - No refactoring needed

## Testing

Created a mock provider implementation to test interface contract.

**Test Results:**

```
✓ src/llm/providers/llm-provider.interface.spec.ts (13 tests) 7ms
  - initialization (2 tests)
  - checkHealth (2 tests)
  - listModels (2 tests)
  - chat (2 tests)
  - chatStream (1 test)
  - embed (2 tests)
  - getConfig (2 tests)
```

**Type Check:** ✅ Passed

## Notes

- Interface should be provider-agnostic
- Use existing DTOs from current LlmService
- Consider async initialization for providers
- Health check should return standardized status