Stacked Marquee Observability Layer

Observability Without Blocking Render

The memoirs homepage is an ambient experience: generative audio, glass typography, and motion layers run continuously. Injecting live trading data into that stack required a design where no single upstream API can freeze the UI.

The banner solves this with three principles:

1. Feed isolation: Crypto uses a Coinbase WebSocket; equities and yields poll /memoirs/api/market; sports polls dedicated API routes. A dead Polymarket call cannot blank BTC prices. 2. Placeholder-first paint: Every band boots with LOADING... tokens, then merges real payloads as they arrive. 3. Last-good-state retention: Failed polls keep the previous marquee text instead of flashing empty error states.

Sports stats and MLB odds are grouped at the start of the sports ticker, followed by up to five upcoming moneyline lines sorted by gameStartTime.