Two things kept the chart quieter than the feed.
Higher timeframes only moved once a minute. Tick bars are 1m and the socket
filters bar events by the subscriber's timeframe, so on the hourly chart every
tick was discarded and only a closed minute passing through the aggregator
showed up. They cannot simply be fed to the aggregator — it accumulates with
current.v += incoming.v, so the same forming minute re-sent on each tick would
add its volume to every higher timeframe again and again. provisional_higher
combines the aggregator's committed state with the live minute instead, without
mutating it; the next closed minute goes through normally and replaces the
result, because the store keys on the bucket timestamp. A test pins the
behaviour: five ticks in one minute leave the hour's volume at closed plus live,
counted exactly once.
Trades known only by their volume were skipped. Level 1 resends only changed
fields, so some trades carry a trade stamp and a moved TOTAL_VOLUME with neither
LAST_PRICE nor LAST_SIZE. Those now count, with size left at zero rather than
guessed from the volume delta — CHART_FUTURES replaces the minute's volume with
the exchange's own figure moments later, and two ways of counting the same
trades is how double counting starts. Measured: 66 to 74 updates per 90s.
The tick throttle drops to 0.25s, which no longer binds. Measured in regular
hours the gaps between updates are whole multiples of 1.005s — 2.01, 3.02,
4.03 — which is Schwab conflating LEVEL_ONE_FUTURES to one update per second
per symbol. One per second is the source's ceiling, not ours; the longer gaps
are seconds in which their feed carried no trade.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Chris Amow
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