@tidal-ts/terminal

For apps where users build their own charts. The terminal package is a state machine (XState v5) that holds the chart's setup: which rows exist, which series and studies sit on each, which axis each one uses, and up to five saved presets. It never fetches, stores or draws data. Peers: React, xstate and @xstate/react.

Its output is the rows that prepareChart takes, so the machine and the chart meet at one shape.

Setting it up

<TerminalProvider initialRows={rows} catalog={metrics} storage={presetStorage} palette={colours}>
  <YourChartAndControls />
</TerminalProvider>

What the host supplies:

Prop	Purpose
initialRows	The starting layout, as RowState rows (an id, a height, configs).
catalog	The metrics a user can add: id, label, colour, unit, source, style, axis.
storage	Where presets live: four functions to load and save presets and the active slot.
palette	Colour keys handed to new series, in order.
spreadColor	A colour reserved for spreads between two series, if you keep one.
inspect	An XState inspector, if you want to watch the machine.

Reading and changing it

Hooks read state (useRows, useSelectedSeries, useAxisRanges, …) and send one kind of change each (useAddSeries, useAddStudy, useSetStudyParam, useMoveToAxis, useSavePreset, …). Every change goes through the machine's rules, so a study is only offered on data that has the columns it reads, removing a series also removes the studies built on it, and an axis move that would mix units is refused.

The same rules are exported as plain functions (allowedAxes, canAddUnit, studyOfferable, …) so your menus can grey out what the machine would refuse.