Exchanges

dccd supports 7 exchanges. Each adapter declares its Capability per data type and transport, and the engine honours them — an unsupported request is rejected early rather than silently returning wrong or partial data.

Capabilities

Exchange	OHLC REST	Trades REST	Book REST	WebSocket (live)
Binance	✅ full	✅ full	✅	OHLC · trades · book
Coinbase	✅ full (300/req)	⚠️ recent only	✅	trades
Kraken	⚠️ 720 recent	✅ full	✅	OHLC · trades · book
Bybit	✅ full	❌ no spot history	✅	OHLC · trades · book
OKX	✅ full	✅ full	✅	OHLC · trades · book
Bitfinex	✅ full	✅ full	✅	OHLC · trades
BitMEX	✅ full (4 spans)	✅ full	✅	OHLC · trades · book

Note

Trades REST is cursor-paginated — a backfill drains the full requested window, not just the first capped page. ⚠️ recent only means the exchange exposes no deep trade history through the public JSON API (a deep request is rejected early, not silently truncated). The WebSocket column lists only channels with a real implementation; undeclared channels raise NoCapability.

OHLC field fidelity

Not every exchange returns every OHLC field natively. Missing fields are stored as null — never fabricated.

Exchange	quote_volume	trades (count)
Binance	✅ native	✅ native
Bybit / OKX	✅ native	— null
Kraken	✅ vwap × volume (exact)	✅ native
Coinbase / Bitfinex / BitMEX	— null	— null

Per-exchange notes

• Binance — full history (klines, aggTrades, depth 5000); the reference implementation for cursor pagination.

• Coinbase — 300 candles/request (windowed automatically); trades are recent only (header cursors are not exposed by the JSON transport).

• Kraken — OHLC REST serves the 720 most recent bars (history="recent"): a deep request is clamped to that window with a warning. Trades are full history via the since cursor.

• Bybit — full OHLC; spot has no trade history (WS only) → declared as NoCapability for trades backfill.

• OKX — deep history via history-candles / history-trades.

• Bitfinex — up to 10 000 items/request. Tether is labelled UST, so BTC/USDT maps to tBTCUST automatically.

• BitMEX — bucketed OHLC (1m/5m/1h/1d only); full trade history.

Adding an exchange

Add an adapter under dccd/sources/ implementing the relevant Source protocol mixins and a capabilities() declaration, then register it in dccd.application.service_factory.build_registry.