feature

Event count

Counts how often a definition fired and lists each event’s time + payload fields.

What it studies

Frequency of bull-bar events — a metric total and a row table.

Key decisions

Piece	Why it matters
`flows.declare({ slug, as })`	Binds Collect data; `as` is the `ctx.event.flow` name.
`ctx.collect` in `onEvent` only	Scratch buckets — not the same as `results.declare` ids.
`ctx.publish` in `onFinish` only	Aggregates after every event has been seen.
Guard `ctx.event.flow !== "bull"`	Ignore other flows if the run attaches more than one.

Full script

meta({ name: "Bull bar count", kind: "study" });

flows.declare({
  slug: "bull-bar",
  as: "bull",
});

results.declare({
  id: "summary",
  kind: "metric",
  title: "Event count",
});

results.declare({
  id: "rows",
  kind: "table",
  title: "Events",
});

export function onEvent(ctx) {
  if (ctx.event.flow !== "bull") return;
  ctx.collect("n", 1);
  ctx.collect("rows", {
    time: ctx.event.time,
    range: ctx.event.payload.range,
  });
}

export function onFinish(ctx) {
  const n = ctx.collected("n").length;
  ctx.publish("summary", { value: n, label: "Events" });
  ctx.publish("rows", ctx.collected("rows"));
}

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