# MultiCombobox

> Multi-select combobox with inline chips, type-to-filter dropdown, label, error, and helper text.

- Status: stable
- Group: form
- Page: https://www.digitaltableteur.com/design-system/components/multi-combobox
- Contract: https://www.digitaltableteur.com/contracts/v1/MultiCombobox.contract.json

## When to use

MultiCombobox picks several options from a list: chosen values render as removable Badge chips on one line inside the field (the ones that do not fit fold into a "+N" Badge), and the inline input filters the dropdown as you type. It is controlled (value: string[], onValueChange) and owns its label/error/helperText chrome. It shares field styling and dropdown mechanics with Combobox.

## When not to use

- Do not use for single-select; use `Combobox` instead.
- Do not use it for exactly-one choice; Combobox and Select stay clearer and cheaper.

## Look-alikes

- Combobox: Do not use for single-select; use `Combobox` instead.
- FilterChip: Do not use FilterChip for multi-select token input; use MultiCombobox.

## Props

| Prop | Type | Default | Description | Required |
| --- | --- | --- | --- | --- |
| `label` | `string` | none | Field label; associates the input. | Yes |
| `options` | `MultiComboboxOption[]` | none | Selectable options. | Yes |
| `value` | `string[]` | none | Selected values (controlled) | Yes |
| `onValueChange` | `(value: string[]) => void` | none | Called with the next selected values. | Yes |
| `id` | `string` | none | Explicit control id (wires the label); auto-generated when omitted. | No |
| `placeholder` | `string` | none | Shown when nothing is selected. | No |
| `helperText` | `string` | none | Assistive text below the field. | No |
| `error` | `string` | none | Error message; renders above the helper line and sets aria-invalid. | No |
| `status` | `FieldStatus` | none | Semantic state: colours the border and styles statusMessage. `error` overrides it. | No |
| `statusMessage` | `string` | none | Message under the field for `status`, above the helper line. | No |
| `actions` | `FieldAction[]` | none | Icon buttons at the end of the label row: each runs an operation or opens a menu. | No |
| `required` | `boolean` | `false` | Marks the field required. | No |
| `disabled` | `boolean` | `false` | Disables the control. | No |
| `className` | `string` | none | Classes on the field wrapper. | No |

## Variants

No variant dimensions and no props with a fixed set of values.

## Invalid combinations

The contract records no invalid combinations.

## Keyboard

| Key | Behaviour |
| --- | --- |
| Tab | Moves between the filter input and the toggle button; leaving the field closes an open list. Options are never Tab stops. |
| Enter | Activates the focused control. (standard) |
| Escape | Closes or dismisses the open layer. (standard) |
| ArrowDown | Opens the list, then moves the highlight to the next enabled option with wrap-around. Disabled options are skipped. |
| ArrowUp | Opens the list, then moves the highlight to the previous enabled option with wrap-around. Disabled options are skipped. |
| Backspace | Named in the contract without a description. |

Rows marked (standard) name a key the contract lists without a description; the behaviour shown is the usual one for that key.

## Rules

Every item under When not to use is a MUST NOT. MUST and SHOULD follow RFC 2119.

| Level | Rule | How it is checked |
| --- | --- | --- |
| MUST | ARIA: Input role=combobox with aria-autocomplete=list, aria-expanded, aria-controls, aria-activedescendant. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Labelled via aria-labelledby. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Listbox role=listbox + aria-multiselectable + aria-label. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Options role=option with aria-selected. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Visible selected values are removable Badge chips; overflow folds into a +N Badge announced as "N more selected: <labels>"; Backspace on an empty filter removes the last value. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Error sets aria-invalid + aria-describedby. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | Required stories produce no axe violations at the configured severity. | Automated by `npm run test:stories:matrix:ci`. WCAG 2.5.8. |
| MUST | The accessibility tree (role, name, state) matches the committed snapshot for every required story. | Automated by `npm run test:stories:matrix:ci`. WCAG 1.3.1, 4.1.2. |
| MUST | The component remains legible and operable under a real browser forced-colors: active pass. | Automated by `npm run test:stories:hc`. |
| MUST | Every documented keyboard interaction works as specified. | Not yet verified: no evidence record. WCAG 2.1.1, 2.1.2. |
| MUST | A human completed an end-to-end accessibility review of this component. | Manual review, last on 2026-11-04. |
| SHOULD | Always control it: keep the selected values in state and hand back the full next array from onValueChange. | Not stated in the contract. |
| SHOULD | Keep option labels short; chips stay on one line, so long labels push more selections into the +N badge and a lone chip wider than the field truncates. | Not stated in the contract. |
| SHOULD | Tell users about Backspace-to-remove in helperText for keyboard-heavy audiences; it deletes the last chip when the filter is empty. | Not stated in the contract. |
| SHOULD | Cap the practical number of selections in your form validation and say so in helperText; selections that do not fit on one line are only summarised in the +N badge. | Not stated in the contract. |
| SHOULD NOT | Do not repurpose the chips as free-form tag creation; values must exist in options (no create-on-enter). | Not stated in the contract. |

## Install and import

- Install: `npm install @digitaltableteur/react` (version 0.9.1, restricted access on npm).
- Import: `import { MultiCombobox } from "@digitaltableteur/react";`
- Entry point: `@digitaltableteur/react/forms` exports it too.
- Styles: import `@digitaltableteur/react/style.css` once at the app boundary.
- Also available as the custom element `<dt-multi-combobox>`; see the custom elements manifest.

## Links

- Machine-readable contract (Design System Contract 1.0): https://www.digitaltableteur.com/contracts/v1/MultiCombobox.contract.json
- Markdown version of this page: https://www.digitaltableteur.com/design-system/components/multi-combobox.md
- Component index as JSON: https://www.digitaltableteur.com/design-system/components.json
- All components: https://www.digitaltableteur.com/design-system/components
- Source: The implementation lives in a private repository. This page, its Markdown twin and the contract are generated from it at build time and are the public source of truth.