# Market Data Service (SenpAI)

Real-time market data collection and normalization for the SenpAI/Gordon trading agent.

## Quick Start

### 1. Install

```bash
cd services/market-data-service
pip install -r requirements.txt
```

### 2. Copy config

```bash
cp .env.example .env
```

### 3. Run (Binance — no keys needed)

```bash
python -m app run --provider binance --symbols BTCUSDT,ETHUSDT
```

### 4. Run (Alpaca — paper trading)

First, get free paper-trading API keys:
1. Sign up at https://app.alpaca.markets
2. Switch to **Paper Trading** in the dashboard
3. Go to API Keys → Generate New Key
4. Add to `.env`:
   ```
   ALPACA_KEY=your_key_here
   ALPACA_SECRET=your_secret_here
   ALPACA_DRY_RUN=false
   ```
5. Run:
   ```bash
   python -m app run --provider alpaca --symbols AAPL,TSLA
   ```

Without keys, Alpaca runs in **dry-run mode** (heartbeats only).

### 5. Run (Bybit — backup crypto, no keys needed)

```bash
python -m app run --provider bybit --symbols BTCUSDT,ETHUSDT
```

### 6. Run all providers

```bash
python -m app run --provider all --symbols BTCUSDT,ETHUSDT,AAPL,TSLA
```

## Docker

### Build & run standalone

```bash
docker build -t market-data-service .
docker run --rm -v mds-data:/data market-data-service run --provider binance --symbols BTCUSDT,ETHUSDT
```

### As part of NODE1 stack

The service is included in `docker-compose.node1.yml`:

```bash
docker-compose -f docker-compose.node1.yml up -d market-data-service
```

Default config: Binance+Bybit on BTCUSDT,ETHUSDT with NATS output enabled.

## HTTP Endpoints

Once running, the service exposes:

| Endpoint | Description |
|---|---|
| `GET /health` | Service health check |
| `GET /metrics` | Prometheus metrics |
| `GET /latest?symbol=BTCUSDT` | Latest trade + quote from SQLite |
| `GET /bus-stats` | Queue size, fill percent, backpressure status |

Default port: `8891` (configurable via `HTTP_PORT`).

## SenpAI Integration (NATS)

Enable NATS output to push events directly to SenpAI:

```env
NATS_URL=nats://localhost:4222
NATS_ENABLED=true
NATS_SUBJECT_PREFIX=md.events
```

Subject schema:
- `md.events.trade.BTCUSDT` — trade events
- `md.events.quote.AAPL` — quote events
- `md.events.heartbeat.__system__` — heartbeats
- `md.events.>` — subscribe to all events

## Backpressure & Reliability

- **Backpressure**: Smart drop policy when queue fills up
  - 80%+ → drop heartbeat events
  - 90%+ → drop quotes (trades are preserved)
  - 100% → drop oldest event
- **Heartbeat monitor**: Emits synthetic heartbeat if provider goes silent
- **Auto-reconnect**: Exponential backoff with resubscribe
- **Failover**: Bybit as backup for Binance with health-based switching

## View Data

### SQLite
```bash
sqlite3 market_data.db "SELECT * FROM trades ORDER BY ts_recv DESC LIMIT 5;"
```

### JSONL Event Log
```bash
tail -5 events.jsonl | python -m json.tool
```

### Prometheus Metrics
```bash
curl http://localhost:8891/metrics
```

Key metrics:
- `market_events_total` — events by provider/type/symbol
- `market_exchange_latency_ms` — exchange-to-receive latency
- `market_events_per_second` — throughput gauge
- `market_gaps_total` — detected gaps per provider

## Architecture

```
Provider (Binance/Bybit/Alpaca)
    │ raw WebSocket messages
    ▼
Adapter (_parse → domain Event)
    │ TradeEvent / QuoteEvent / BookL2Event
    ▼
EventBus (asyncio.Queue fan-out + backpressure + heartbeat)
    ├─▶ StorageConsumer  → SQLite + JSONL
    ├─▶ MetricsConsumer  → Prometheus counters/histograms
    ├─▶ PrintConsumer    → structured log (sampled 1/N)
    └─▶ NatsConsumer     → NATS PubSub (for SenpAI)
    
FailoverManager
    monitors provider health → switches source on degradation
```

## Adding a New Provider

1. Create `app/providers/your_provider.py`
2. Subclass `MarketDataProvider`:

```python
from app.providers import MarketDataProvider
from app.domain.events import Event, TradeEvent

class YourProvider(MarketDataProvider):
    name = "your_provider"

    async def connect(self) -> None: ...
    async def subscribe(self, symbols: list[str]) -> None: ...
    async def stream(self) -> AsyncIterator[Event]:
        while True:
            raw = await self._receive()
            yield self._parse(raw)
    async def close(self) -> None: ...
```

3. Register in `app/providers/__init__.py`:
```python
from app.providers.your_provider import YourProvider
registry["your_provider"] = YourProvider
```

4. Add config to `app/config.py` if needed
5. Run: `python -m app run --provider your_provider --symbols ...`

## Tests

```bash
pytest tests/ -v
```

36 tests covering:
- Binance message parsing (7 tests)
- Alpaca message parsing (8 tests)
- Bybit message parsing (9 tests)
- Event bus: fanout, backpressure, heartbeat (7 tests)
- Failover manager (5 tests)

## CI

Included in `.github/workflows/python-services-ci.yml`:
- `ruff check` — lint
- `pytest` — unit tests
- `compileall` — syntax check

## Troubleshooting

### Port 8891 already in use
```bash
lsof -ti:8891 | xargs kill -9
```

### NATS connection refused
If `NATS_ENABLED=true` but NATS is not running, the service starts normally — NATS output is skipped with a warning log. To run without NATS:
```env
NATS_ENABLED=false
```

### SQLite "database is locked"
Normal under heavy load — SQLite does not support concurrent writers. The service uses a single async writer. If you see this in external tools (`sqlite3` CLI), wait for the service to stop or use the `/latest` HTTP endpoint instead.

### Binance WebSocket disconnects
Auto-reconnect is built in with exponential backoff (1s → 60s max). Check logs for `binance.reconnecting`. If persistent, verify DNS/firewall access to `stream.binance.com:9443`.

### Bybit "subscribe_failed"
Verify symbol names match Bybit spot conventions (e.g. `BTCUSDT`, not `BTC-USDT`). Check `bybit.subscribe_failed` in logs.

### No data for Alpaca symbols
Without API keys, Alpaca runs in **dry-run mode** (heartbeats only). Set `ALPACA_KEY`, `ALPACA_SECRET` and `ALPACA_DRY_RUN=false` in `.env`.

### JetStream not available
If `USE_JETSTREAM=true` but NATS was started without `--js`, you'll see a connection error. Start NATS with JetStream:
```bash
docker run -d -p 4222:4222 nats:2.10-alpine --js
```

## TODO: Future Providers

- [ ] CoinAPI (REST + WebSocket, paid tier)
- [ ] IQFeed (US equities, DTN subscription)
- [ ] Polygon.io (real-time + historical)
- [ ] Interactive Brokers TWS API
- [ ] Coinbase WebSocket (backup crypto #2)