# Tags (`tags`)

Multi-value chips + free create — a native text input carrying a comma-joined value, progressively enhanced into a chips UI. JS off: a usable comma-separated text field. JS on: type + Enter/comma creates a chip, blur commits a leftover token, × removes; the native input stays as the submitted value.

> **Layer:** L1 surface · **Recipe:** `multi-label-form` — multi free-form labels
> Curriculum: `AGENTS.md` · pick matrix: `docs/agent/pick-a-surface.md` · blast radius: `CONSUMER_MAP.md`

> **Dialect:** Partial below is **unprefixed** (gallery / standalone HM). DOM contract Python often uses the **source token** `data-dz-*` / `dz-*` (Dazzle dual-lock). Match the CSS/JS bundle you load.

> **Demo vs contract:** Live gallery behaviour may use `/mock/*` or flash toasts. Those are **offline demos only** — implement **Server exchange** + **DOM contract**, not the mock. See AGENTS.md › Gallery demos.

## Copy this

```html
<label class="field hm-measure" for="hm-tags-field"><span class="field__label">Labels</span><input id="hm-tags-field" name="labels" type="text" data-tags class="form-input" value="urgent,backend" placeholder="Add a label…"></label>
```

## Server exchange

This Hyperpart has **no server exchange** — presentation or client chrome only. If you put `hx-*` on a control that uses this markup, that action's exchange belongs to the action, not this part.

## Swap contract

Agent-visible HTMX topology (ADR-0054 / decision 0012). **Exchange envelope** = what the response may re-emit relative to the persistent slot (`body_only` | `outer` | `none` | `host_owned` | `document`). Dual-lock validates part markup only — not this envelope. Stem: `stems/morph-safe-hypermedia.md`.

**No host HTMX exchange** on this part — presentation or client chrome only. **Exchange envelope:** `n/a`.

If a **host** wraps this markup in `hx-*`, **that host owns the swap contract** (sole identity + envelope). Prefer `innerMorph` / `outerMorph` for stable slots; replacement for flash; body-only responses under inner swaps.

### Envelope response examples

What the **server returns** for each exchange. Match the **exchange envelope**; dual-lock still applies to interior markup.

This part has no owned exchange (envelope `n/a`). If a host adds `hx-*`, that host’s envelope applies — typically `body_only`:

```html
<!-- Prefer hx-swap=innerMorph into a stable body slot -->
<div class="dz-stack">content…</div>
```

Do **not** re-own the slot:

```html
<div id="tags-root" data-dz-region>…</div>
```

## How to use it

### Seams

- native input value is a comma-joined tag string — the permanent submit shape
- chips UI rewrites the native input on every add/remove and fires change

### Do / Don't

| Do | Don't |
|---|---|
| keep the native input as the form value under the chips root | post a JSON array the server has never seen from a plain field |

### Pitfalls

- JS off: type a, b, c — server splits on comma; do not require the chips UI
- dedupe/trim/skip-empty on add; paste splits on comma and newline

### Keyboard / AT

- chips are role=list of listitem; each × is labelled Remove {tag}
- Enter or comma creates a chip; blur commits leftover; Backspace on empty entry removes the last

### Related parts

- `field` — agents/field.md

## DOM contract

What emitted markup must satisfy (CI: `tests/test_contracts.py`). Do not invent attrs outside the tables. Python modules under `contracts/` are **package-internal dual-locks** (`from contracts._kit import …`) — not FastAPI business handlers. App servers implement **Server exchange** endpoints; this section constrains the HTML those endpoints return.

### `contracts/tags.py`

- **Required root:** `[data-dz-tags]` (part `tags`)

| Node | Attr | Constraint |
|---|---|---|
| `[data-dz-tags]` | `name` | present (any value) |

#### Ingestion model `TagsField`

| Field | Type | Required |
|---|---|---|
| `name` | `string` | yes |
| `field_id` | `string` | yes |
| `label` | `string` | yes |
| `tags` | `array` | no |
| `placeholder` | `string` | no |

#### Exemplar `render()`

```python
def render(field: TagsField) -> str:
    joined = ",".join(field.tags)
    return (
        f'<label class="dz-field" for="{html.escape(field.field_id, quote=True)}">'
        f'<span class="dz-field__label">{html.escape(field.label)}</span>'
        f'<input id="{html.escape(field.field_id, quote=True)}" '
        f'name="{html.escape(field.name, quote=True)}" type="text" data-dz-tags '
        f'class="dz-form-input" value="{html.escape(joined, quote=True)}" '
        f'placeholder="{html.escape(field.placeholder, quote=True)}"></label>'
    )
```

## Notes

Progressive enhancement: the server renders a plain <input type="text" data-dz-tags> whose value is a COMMA-JOINED tag string — usable and submittable with no JS (type a, b, c; the server splits on comma), native required intact. Seeded non-empty values enhance on DOM ready; empty fields enhance on first interaction. dz-tags.js wraps the input in a .dz-tags root — a role="list" of removable chips + a borderless entry — and hides the native input (kept in the DOM as the submitted value). Every add/remove rewrites the native input to the comma-joined chip list and fires change, so the submit shape never changes. Type + Enter or comma creates a chip (trim/dedup/skip-empty); leftover typed text commits on blur (must not vanish — cycle 2131); paste splits on comma/newline; × or Backspace-on-empty removes a chip; add/remove is announced via a visually-hidden aria-live region.

## Source files

- `site/registry.py` (partial + exchanges + guidance)
- `contracts/tags.py`
- `controllers/dz-tags.js`