Adds backend/engine/runner.py with run_single() that iterates pipeline stages,
renders Jinja2 prompt templates with stage history context, checks/stores response
cache, calls LLM adapters, runs configured scorers, creates StageResult and Score
records, and publishes progress events via Redis pub/sub or in-process EventBus.
Includes 21 passing tests covering all execution paths.
Add OpenAICompatAdapter that works with any OpenAI-compatible API endpoint
(OpenWebUI, vLLM, Ollama, OpenAI, Anthropic via proxy). Features:
- Async HTTP calls via httpx with configurable timeout
- Chat completions format with system + user messages
- Token usage parsing from responses
- Exponential backoff retries (configurable, default 3 attempts)
- Both streaming (SSE) and non-streaming modes
- Model listing and connection testing
- 21 tests covering construction, request building, response parsing,
retry logic, and error handling
Define the LLM adapter interface in backend/engine/adapters/base.py with
async methods complete(), list_models(), and test_connection(). The
AdapterResponse dataclass holds response text, token counts, latency,
model name, and raw metadata. Includes 11 tests covering instantiation
guards, concrete subclass behavior, and dataclass semantics.
