Field types

The 11 field types available on an input step, and the modifiers any field can take.

Defined in platform/contracts/src/authoring-fields.ts.

The types

Type	Stores	Notes
`bool`	boolean	Checkbox.
`string`	string	Single line.
`string-multiline`	string	Textarea.
`number`	number
`decimal_string`	string	Decimal held as a string to avoid float loss. Use for token amounts.
`datetime`	string
`dropdown`	string	Requires `values[]`, or `choices.recipe` for a list computed from the current instant (see choice lists).
`file-single`	file ref	`ProcessFileRef`; the file itself lives under `PROCESS_FILES_ROOT`.
`file-multiple`	file refs
`item_list`	array of rows	Repeating group. Requires `subInputs[]`. Nesting is allowed.
`header`	nothing	Display only — never written to context.

header takes headerLevel (section by default, or subsection) and may use defaultValue as subtitle HTML.

Modifiers

Any field may carry these.

Modifier	Effect
`title`	Label. Required.
`mandatory`	Blocks Continue until populated. Hidden and read-only fields are not enforced.
`hint`	Tooltip beside the label.
`placeholder`	`string`, `string-multiline`, `number`, `decimal_string` only.
`visibleExpression`	Show/hide. A hidden mandatory field does not block.
`values[]`	Options for `dropdown`. Changing them is a template change.
`choices`	`dropdown` only, instead of `values[]`: `{ recipe }`, an expression over the current instant alone that returns the options. Checked again on the server whenever a value is written. See choice lists.
`permissions[]`	Per-field editability (OR). Users without a match see it read-only. Empty or omitted means anyone who can act on the step. Same matching rules as step-level permissions.
`readOnly`	Renders as resolved text from `defaultValue`. This is how view-control fields are built.
`defaultValue`	Read-only: the template to resolve. Editable: the initial value. Both support `${path}` and `{{ expression }}`.
`downloadFilename`	Read-only fields only. Adds a download button saving resolved `defaultValue` under this name. Supports `{{ expression }}` — e.g. `payload-{{ todayIsoDate() }}.json`. Use for generated payloads instead of copy-paste.
`subInputs[]`	`item_list` only. The fields making up one row.

Subroutines

An input step's inputs[] accepts either a leaf field or a subroutine reference (TemplateStepInputSubroutine, domain/shared/src/authoring.ts):

{ type: "subroutine", key: "curve_verify", subroutineId: "safe_ui_verification", params: {…} }

A subroutine is a reusable group of fields defined in TypeScript under the Domain library, expanded into generic leaf fields at authoring/compilation by expandTemplateInputSubroutines().

params typically carries prefix, URLs, titles, fieldHints, and mandatoryKeys.

Compare like-for-like compiled presentations or normalized source. Public Process views already contain generic expanded fields; the browser must not re-run domain macro expansion.

Where values land

An input step writes to context[stepKey], keyed by field key:

context.s01_deal_registration = {
  _dealName: "Acme",
  _prime: "Spark",
}

Every write appends a StepContextAuditEntry. Fields the caller lacks permission for are filtered out before the merge — a rejected field write is silently dropped, not an error.