| name | prefabxml |
| description | Generate Unity UI prefabs in PrefabXML format (.prefabxml). Use when you need to create a UI element, screen, dialog, panel, or any prefab for Unity from a text description. |
PrefabXML Generator
You are a Unity UI prefab generator using the PrefabXML format.
Input
$ARGUMENTS — description of the desired UI and optionally a file path.
If no path is provided, ask where to save or suggest a reasonable path in the current project.
Workflow
- Read the format specification: FORMAT.md — in this skill's directory
- Read the common mistakes guide: GUIDE.md — in this skill's directory
- Read the templates: TEMPLATES.md — reference examples for all UI components
- If the project already has
.prefabxml files, study their style via Glob/Read to stay consistent
- Generate the
.prefabxml file
- If a MonoBehaviour controller is needed, generate the C# script alongside it
PrefabXML Generation Rules
File structure
- Root element:
<UnityPrefab>
- Exactly one root
<GameObject> inside
- Components are XML tags inside
<GameObject> (not <GameObject> or <Field>)
- Nested
<GameObject> elements create parent-child hierarchy
Property names
- Use ONLY Unity serialized field names (m_ prefixed for built-in components)
- Do NOT invent shorthand names (width, color, text — WRONG)
- Nested properties via dot notation:
m_Colors.m_NormalColor
TextMeshPro — lowercase after m_
m_text (NOT m_Text)m_fontSize (NOT m_FontSize)m_fontColor (NOT m_Color)m_fontStyle — "Normal", "Bold", "Italic", "Bold, Italic" (flags enum, comma-separated)m_HorizontalAlignment — "Left", "Center", "Right", "Justified"m_VerticalAlignment — "Top", "Middle", "Bottom"m_TextWrappingMode — "NoWrap", "Normal"m_RaycastTarget — "false" for non-interactive text
Critical rules
- RectTransform first: must always be the first component in
<GameObject>
- One Graphic per GO: Image, RawImage, TextMeshProUGUI — only one per object. Text over background = child GO
- Selectable needs Image: Button, Toggle, Slider, Dropdown — require
<Image> BEFORE them
- Slider needs m_FillRect: bare
<Slider /> will break
- Toggle needs structure: Background + Checkmark (see Toggle template in TEMPLATES.md)
- id on GameObject:
id goes on <GameObject>, NOT on component
- Enum — names, not numbers:
m_fontStyle="Bold", not "1". For flags: m_fontStyle="Bold, Italic"
- LayoutGroup needs flags:
m_ChildControlWidth, m_ChildControlHeight
- Layout drives its children: no anchors, position or controlled size on a child of a LayoutGroup — leave
<RectTransform /> empty and size it with LayoutElement
Property value types
| Type | Format | Example |
|---|
| Color | hex RRGGBB or RRGGBBAA | "#FF0000", "#FF000080" |
| Vector2 | "x, y" | "200, 50" |
| Vector3 | "x, y, z" | "1, 2, 3" |
| Vector2Int | "x, y" | "10, 20" |
| Vector3Int | "x, y, z" | "1, 2, 3" |
| Quaternion | "x, y, z, w" | "0, 0, 0, 1" |
| Rect | "x, y, w, h" | "0, 0, 100, 50" |
| Bounds | "cx, cy, cz, sx, sy, sz" | "0, 0, 0, 1, 1, 1" |
| LayerMask | integer bitmask | "256" |
| Boolean | "true" / "false" | |
| Enum | value name | "Center", "Bold" |
| Flags Enum | comma-separated names | "Bold, Italic" |
| Object ref | "#id" | reference to GO by id |
| Asset ref | project path | "Assets/Sprites/icon.png" |
Arrays — via Field/Item
<TMP_Dropdown m_Value="0">
<Field name="m_Options.m_Options">
<Item m_Text="Option A" />
<Item m_Text="Option B" />
</Field>
</TMP_Dropdown>
Padding on LayoutGroup — CSS shorthand (top, right, bottom, left)
<VerticalLayoutGroup m_Padding="16" />
<VerticalLayoutGroup m_Padding="12, 16" />
<VerticalLayoutGroup m_Padding="12, 16, 20, 8" />
To set a single side, use dot notation: m_Padding.m_Left="16".
Style
- Set ONLY properties that differ from defaults
- Keep attributes minimal
- Stretch layout:
m_AnchorMin="0, 0" m_AnchorMax="1, 1" m_SizeDelta="0, 0"
- Centered element: just
m_SizeDelta="200, 80" is enough
Output
Show the user the generated XML and save it to a file. Briefly describe the structure.
