Overview

A definition is a script that marks every bar where a setup appears. Run it over history and each mark becomes an event you can browse and study.

In the app the noun is always definition. In code the API word is flow: meta({ kind: "flow" }), FlowCtx, and tool names such as lint_flow. A definition runs through the same runtime as an indicator, so bars, inputs, drawing, dependencies and timeframes all work the same way. This section covers what only definitions have: events, ctx.emit, and multi-file packages.

Definitions library — Tools → Definitions: named setups ready to run over history and study.

Covered in Shared runtime

Topic	Page
`outputs.declare` with `ctx.plot`, `mark`, `hline`, `range`, `note`, `trendline`	Drawing on the chart
`indicators.declare`	Declaring indicator dependencies
`input.*`, `dialog`, `layout`	Settings inputs and dialog
`ctx.accum` and `warmup`	Remembering values across bars
`ctx.session(opts)`	Sessions
`timeframe(...)` handles and `runOn`	Timeframe handles and runOn

Unique to definitions

Page	Covers
Meta	`kind: "flow"`, `slug`, `window`, settings and profiles
Events and snapshots	`events.declare`, payload schema, `paint`, `oncePer`, `snapshots.declare`
Emit and labels	`ctx.emit` and its options, the required `label`
onBar	How `onBar` runs on the chart and over history
Multi-file packages and imports	Relative ESM, entry rules, `imports.use`
Examples	Bull bar, EMA cross, OR break

Minimal definition

meta({ name: "Tick Signal", kind: "flow", slug: "tick-signal" });

events.declare({
  id: "tick",
  intent: "alert",
  payload: { reason: { type: "string", description: "Why this fired" } },
  paint: "pin",
});

outputs.declare({ id: "close_line", kind: "line", name: "Close" });

export function onBar(ctx) {
  ctx.plot("close_line", ctx.close);
  if (ctx.close > ctx.open) {
    ctx.emit("tick", { reason: "bullish_bar" }, {
      label: "Bull bar",
      price: ctx.close,
    });
  }
}

Three parts make an event: the id is declared with events.declare, onBar calls ctx.emit with that id, and the call carries a label. Miss any one and the event is dropped.

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