prefabxml

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

1. Read the format specification: FORMAT.md — in this skill's directory
2. Read the common mistakes guide: GUIDE.md — in this skill's directory
3. Read the templates: TEMPLATES.md — reference examples for all UI components
4. If the project already has .prefabxml files, study their style via Glob/Read to stay consistent
5. Generate the .prefabxml file
6. 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.