feat: add initial Hold Slayer AI telephony gateway implementation

Complete project scaffolding and core implementation of an AI-powered telephony system that calls companies, navigates IVR menus, waits on hold, and transfers to the user when a human answers. Key components: - FastAPI server with REST API, WebSocket, and MCP (SSE) interfaces - SIP/VoIP call management via PJSUA2 with RTP audio streaming - LLM-powered IVR navigation using OpenAI/Anthropic with tool calling - Hold detection service combining audio analysis and silence detection - Real-time STT (Whisper/Deepgram) and TTS (OpenAI/Piper) pipelines - Call recording with per-channel and mixed audio capture - Event bus (asyncio pub/sub) for real-time client updates - Web dashboard with live call monitoring - SQLite persistence via SQLAlchemy with call history and analytics - Notification support (email, SMS, webhook, desktop) - Docker Compose deployment with Opal VoIP and Opal Media containers - Comprehensive test suite with unit, integration, and E2E tests - Simplified .gitignore and full project documentation in README
2026-03-21 19:23:26 +00:00
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+# Development
+
+## Setup
+
+### Prerequisites
+
+- Python 3.13+
+- Ollama (or any OpenAI-compatible LLM) — for IVR menu analysis
+- Speaches or Whisper API — for speech-to-text (optional for dev)
+- A SIP trunk account — for making real calls (optional for dev)
+
+### Install
+
+```bash
+git clone <repo-url>
+cd hold-slayer
+python -m venv .venv
+source .venv/bin/activate
+pip install -e ".[dev]"
+```
+
+### Dev Dependencies
+
+The `[dev]` extras include:
+
+- `pytest` — test runner
+- `pytest-asyncio` — async test support
+- `pytest-cov` — coverage reporting
+
+## Testing
+
+### Run All Tests
+
+```bash
+pytest tests/ -v
+```
+
+### Run Specific Test Files
+
+```bash
+pytest tests/test_audio_classifier.py -v   # 18 tests — waveform analysis
+pytest tests/test_call_flows.py -v          # 10 tests — call flow models
+pytest tests/test_hold_slayer.py -v         # 20 tests — IVR nav, EventBus, CallManager
+pytest tests/test_services.py -v            # 27 tests — LLM, notifications, recording,
+                                            #             analytics, learner, EventBus
+```
+
+### Run with Coverage
+
+```bash
+pytest tests/ --cov=. --cov-report=term-missing
+```
+
+### Test Architecture
+
+Tests are organized by component:
+
+| File | Tests | What's Covered |
+|------|-------|----------------|
+| `test_audio_classifier.py` | 18 | Silence, tone, DTMF, music, speech detection; feature extraction; classification history |
+| `test_call_flows.py` | 10 | CallFlowStep types, CallFlow navigation, serialization roundtrip, create/summary models |
+| `test_hold_slayer.py` | 20 | IVR menu navigation (6 intent scenarios), EventBus pub/sub, CallManager lifecycle, MockSIPEngine |
+| `test_services.py` | 27 | LLMClient init/stats/chat/JSON/errors/IVR analysis, NotificationService event mapping, RecordingService paths, CallAnalytics summaries, CallFlowLearner build/merge, EventBus integration |
+
+### Known Test Issues
+
+`test_complex_tone_as_music` — A synthetic multi-harmonic tone is classified as `LIVE_HUMAN` instead of `MUSIC`. This is a known edge case. Real hold music has different spectral characteristics than synthetic test signals. This test documents the limitation rather than a bug.
+
+### Writing Tests
+
+All tests use `pytest-asyncio` for async support. The test configuration in `pyproject.toml`:
+
+```toml
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+```
+
+This means all `async def test_*` functions automatically run in an asyncio event loop.
+
+**Pattern for testing services:**
+
+```python
+import pytest
+from services.llm_client import LLMClient
+
+class TestLLMClient:
+    def test_init(self):
+        client = LLMClient(base_url="http://localhost:11434/v1", model="llama3")
+        assert client._model == "llama3"
+
+    @pytest.mark.asyncio
+    async def test_chat(self):
+        # Mock httpx for unit tests
+        ...
+```
+
+**Pattern for testing EventBus:**
+
+```python
+import asyncio
+from core.event_bus import EventBus
+from models.events import EventType, GatewayEvent
+
+async def test_publish_receive():
+    bus = EventBus()
+    sub = bus.subscribe()
+    
+    event = GatewayEvent(type=EventType.CALL_STARTED, call_id="test", data={})
+    await bus.publish(event)
+    
+    received = await asyncio.wait_for(sub.get(), timeout=1.0)
+    assert received.type == EventType.CALL_STARTED
+```
+
+## Project Conventions
+
+### Code Style
+
+- **Type hints everywhere** — All function signatures have type annotations
+- **Pydantic models** — All data structures are Pydantic BaseModel or dataclass
+- **Async by default** — All I/O operations are async
+- **Logging** — Every module uses `logging.getLogger(__name__)`
+- **Docstrings** — Module-level docstrings explain purpose and usage
+
+### File Organization
+
+```
+module.py
+├── Module docstring (purpose, usage examples)
+├── Imports (stdlib → third-party → local)
+├── Constants
+├── Classes
+│   ├── Class docstring
+│   ├── __init__
+│   ├── Public methods (async)
+│   └── Private methods (_prefixed)
+└── Module-level functions (if any)
+```
+
+### Error Handling
+
+- **Services never crash the call** — All service errors are caught, logged, and return sensible defaults
+- **LLM failures** return empty string/dict — the Hold Slayer falls back to waiting
+- **SIP errors** publish `CALL_FAILED` events — the user is notified
+- **HTTP errors** in the API return structured error responses
+
+### Event-Driven Architecture
+
+All components communicate through the EventBus:
+
+1. **Publishers** — SIP engine, Hold Slayer, classifier, services
+2. **Subscribers** — WebSocket handler, MCP server, notification service, analytics
+
+This decouples components and makes the system extensible. Adding a new feature (e.g., Slack notifications) means subscribing to events — no changes to existing code.
+
+### Dependency Injection
+
+The `AIPSTNGateway` owns all services and is injected into FastAPI routes via `api/deps.py`:
+
+```python
+# api/deps.py
+async def get_gateway() -> AIPSTNGateway:
+    return app.state.gateway
+
+# api/calls.py
+@router.post("/outbound")
+async def make_call(request: CallRequest, gateway: AIPSTNGateway = Depends(get_gateway)):
+    ...
+```
+
+This makes testing easy — swap the gateway for a mock in tests.
+
+## Contributing
+
+1. Create a feature branch
+2. Write tests for new functionality
+3. Ensure all tests pass: `pytest tests/ -v`
+4. Follow existing code conventions
+5. Update documentation in `/docs` if adding new features
+6. Submit a pull request