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Public Channels

Public channels are unauthenticated and keyed by numeric marketId. Book levels are [price, qty] string pairs in micro-units ("1000000" = 1.0), so they survive JavaScript number limits.

The direct institutional endpoints expose the identical frame contract at wss://md.sentico-labs.xyz:9002/api/v1/ws/public and port 9003. They require SC-HMAC-V2 upgrade headers from an active machine credential with read scope; an anonymous upgrade receives HTTP 401. Sign GET, the exact path and query, and an empty body as described in Authentication. Ports 9002 and 9003 terminate in separate listener processes and can be used as independent network paths. They do not change the event timestamp semantics or sequence contract described below.

Channels​

ChannelScopePayload
marketSnapshotMarketThe full public snapshot: book (yes/no for outcome markets, spot for spot markets), mids, last prices, 24 h volume and reference prices, recent trades, topOfBookChecksum
l2BookMarket{ marketId, seq, prevSeq, stateVersion, topOfBookChecksum, book } — the same book object, without the surrounding statistics
tradesMarket{ marketId, seq, prevSeq, stateVersion, topOfBookChecksum, trades[] } — public trade tape without account fields
bboMarket{ marketId, seq, prevSeq, stateVersion, topOfBookChecksum, spot: { bid, ask } } for spot markets, yes/no best levels for outcome markets
activeAssetCtxMarketPer-market context (mids, last, 24 h reference); the compact companion to marketSnapshot

Private fields are stripped before public frames leave the server; the topOfBookChecksum lets you verify that your local top of book matches the server after applying a frame.

Subscribe​

{ "id": "sub-1", "method": "subscribe", "subscription": { "type": "l2Book", "marketId": 3, "depth": 20 } }
{ "id": "sub-2", "method": "subscribe", "subscription": { "type": "trades", "marketId": 3, "limit": 50 } }
{ "id": "sub-3", "method": "subscribe", "subscription": { "type": "bbo", "marketId": 14 } }

The server first completes the durable replay or snapshot bootstrap. It then sends an acknowledgement that echoes the subscription and states snapshotSeq and liveFromSeq, followed by snapshot_end; only then does live delivery begin. A new typed-V2 stream can bootstrap at snapshotSeq: 0; in that case liveFromSeq is 1 and the first delta carries prev_seq: 0.

Orderbook pattern​

  1. Subscribe to l2Book for the market.
  2. Apply the snapshot the server sends after the ack (or fetch GET /api/v1/public/markets/{marketId}/orderbook?depth=N&book=SPOT|YES|NO and drop frames with seq <= snapshot seq). The REST levels are { "price_micros": 100000, "total_qty": "1000" } objects; total_qty is the base-asset quantity in micro-units (the same scale as the trade tape's qty), always a multiple of the market's lotSizeMicro. There is no /book route.
  3. Apply deltas only while prev_seq equals the last seq you applied.
  4. Compare topOfBookChecksum after each frame; on a mismatch or a gap, resubscribe with fromSeq set to the last good sequence, and if the server answers resume_required, rebuild from REST.

Placement status on the recoverable market feed​

The snapshot-and-delta endpoints at /api/v1/feed/public, /api/v1/feed/public/a, and /api/v1/feed/public/b send a global status frame right after the connection's session frame and whenever order placement readiness changes:

{
  "type": "status",
  "sessionState": "cancel_only",
  "placementReady": false,
  "cancelOnlyAvailable": true,
  "reason": "execution persistence degraded (1 unrecovered job(s))",
  "tsMs": 1786259008273
}

This is connection state rather than sequenced market data. It has no seq, prev_seq, marketId, or channel, is not replayed, and must not take part in gap detection. Stop new placement when placementReady is false; cancelOnlyAvailable says whether cancellation still works. GET /api/v1/status remains available as a fallback after reconnects.

What the top-level ts measures​

On /api/v1/ws/public, the server sets ts when it constructs the outgoing JSON envelope in senticore_ws_frame. Engine apply, durable projection and any SQL replay lookup have already happened by then. The remaining path is JSON serialization, the frame cache, async task scheduling, the awaited WebSocket send, the host TCP stack, edge proxy/CDN and the client receive loop.

Frames served from the serialization cache keep the timestamp from the first encoding of that exact frame. Treat client_receive_time - ts as an approximate gateway-to-client age, not as engine-to-client latency. The server's internal apply_to_socket_write timing ends after the awaited socket send and does not prove that the client received the bytes. These two measurements have different start and end points and must not be added as if they were adjacent stages.

Limits​

The session frame carries maxSubscriptionsPerConnection and publicMaxMarketsPerConnection. Exceeding either sends an error frame with code 1008 and the rejected request id, then closes the connection with code 4409. Market makers that need many markets should open several connections. The redundant /feed/public/a + /b feed uses one market and one channel per connection and is intended for latency-sensitive consumers.

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