JSON Render UI Skill for Claude

JSON Render UI

Overview

Transform natural language UI requests into working dashboards and applications. Claude acts as the translation layer (prompt → JSON), the skill provides the rendering runtime (JSON → UI).

Architecture:

User prompt → Claude (constrained by catalog) → UITree JSON → Preact renderer → UI

Output Format

Claude emits a UITree structure:

{
  "root": "main",
  "elements": {
    "main": {
      "key": "main",
      "type": "Grid",
      "props": { "columns": 2, "gap": "md" },
      "children": ["metric1", "metric2"]
    },
    "metric1": {
      "key": "metric1",
      "type": "Metric",
      "props": {
        "label": "Revenue",
        "valuePath": "/revenue",
        "format": "currency"
      }
    },
    "metric2": {
      "key": "metric2",
      "type": "Metric",
      "props": {
        "label": "Growth",
        "valuePath": "/growth",
        "format": "percent"
      }
    }
  },
  "data": {
    "revenue": 125000,
    "growth": 0.15
  }
}

Component Catalog

Claude can ONLY use these components. This is the guardrail.

Layout Components

| Component | Props | Children | Description |

|-----------|-------|----------|-------------|

| Card | title?, description?, padding?: sm\|md\|lg | Yes | Container with optional header |

| Grid | columns?: 1-4, gap?: sm\|md\|lg | Yes | CSS grid layout |

| Stack | direction?: horizontal\|vertical, gap?: sm\|md\|lg, align?: start\|center\|end\|stretch | Yes | Flexbox stack |

Data Display

| Component | Props | Children | Description |

|-----------|-------|----------|-------------|

| Metric | label, valuePath, format?: number\|currency\|percent, trend?: up\|down\|neutral, trendValue? | No | Single KPI display |

| Chart | type: bar\|line\|pie\|area, dataPath, title?, height? | No | Data visualization |

| Table | dataPath, columns: [{key, label, format?: text\|currency\|date\|badge}] | No | Tabular data |

| List | dataPath, emptyMessage? | Yes | Rendered list from array |

Interactive

| Component | Props | Children | Description |

|-----------|-------|----------|-------------|

| Button | label, action, variant?: primary\|secondary\|danger\|ghost, size?: sm\|md\|lg, disabled? | No | Clickable action |

| Select | label?, bindPath, options: [{value, label}], placeholder? | No | Dropdown select |

| DatePicker | label?, bindPath, placeholder? | No | Date input |

Typography

| Component | Props | Children | Description |

|-----------|-------|----------|-------------|

| Heading | text, level?: h1\|h2\|h3\|h4 | No | Section heading |

| Text | content, variant?: body\|caption\|label, color?: default\|muted\|success\|warning\|danger | No | Text paragraph |

Status

| Component | Props | Children | Description |

|-----------|-------|----------|-------------|

| Badge | text, variant?: default\|success\|warning\|danger\|info | No | Status indicator |

| Alert | type: info\|success\|warning\|error, title, message?, dismissible? | No | Notification banner |

Special

| Component | Props | Children | Description |

|-----------|-------|----------|-------------|

| Divider | label? | No | Visual separator |

| Empty | title, description?, action?, actionLabel? | No | Empty state |

Data Binding

Props ending in Path (e.g., valuePath, dataPath, bindPath) reference the data model using JSON Pointer syntax:

• /revenue → data.revenue
• /users/0/name → data.users[0].name
• /filters/dateRange → data.filters.dateRange

Visibility Conditions

Any element can have a visible property:

{
  "type": "Alert",
  "props": { "type": "error", "title": "Error" },
  "visible": { "path": "/hasError" }
}

Visibility expressions:

• true / false — Static
• { "path": "/some/path" } — Truthy check
• { "and": [...] } — All conditions true
• { "or": [...] } — Any condition true
• { "not": {...} } — Negation
• { "eq": [a, b] } — Equality

Generating Output

Step 1: Emit UITree JSON

Analyze the user's request and emit a UITree structure. Include sample data that matches the schema.

Step 2: Create Artifact

Create an HTML artifact that:

• Embeds the UITree JSON
• Renders the UI

Start from assets/template.html, which already carries the embedded renderer —

there is no separate renderer.js to inline.

Constraints

DO:

• Use only catalog components
• Provide realistic sample data
• Use semantic component choices (Metric for KPIs, Table for tabular data)
• Keep trees flat (no deep nesting beyond 3 levels)

DO NOT:

• Invent new component types
• Use arbitrary HTML/CSS
• Omit required props
• Create deeply nested structures

Example

User: "Create a sales dashboard with revenue, orders, and a chart showing monthly trends"

Claude outputs:

{
  "root": "dashboard",
  "elements": {
    "dashboard": {
      "key": "dashboard",
      "type": "Stack",
      "props": { "direction": "vertical", "gap": "lg" },
      "children": ["header", "metrics", "chartCard"]
    },
    "header": {
      "key": "header",
      "type": "Heading",
      "props": { "text": "Sales Dashboard", "level": "h1" }
    },
    "metrics": {
      "key": "metrics",
      "type": "Grid",
      "props": { "columns": 3, "gap": "md" },
      "children": ["revenue", "orders", "avgOrder"]
    },
    "revenue": {
      "key": "revenue",
      "type": "Card",
      "props": { "padding": "md" },
      "children": ["revenueMetric"]
    },
    "revenueMetric": {
      "key": "revenueMetric",
      "type": "Metric",
      "props": {
        "label": "Total Revenue",
        "valuePath": "/revenue",
        "format": "currency",
        "trend": "up",
        "trendValue": "12%"
      }
    },
    "orders": {
      "key": "orders",
      "type": "Card",
      "props": { "padding": "md" },
      "children": ["ordersMetric"]
    },
    "ordersMetric": {
      "key": "ordersMetric",
      "type": "Metric",
      "props": {
        "label": "Orders",
        "valuePath": "/orders",
        "format": "number"
      }
    },
    "avgOrder": {
      "key": "avgOrder",
      "type": "Card",
      "props": { "padding": "md" },
      "children": ["avgMetric"]
    },
    "avgMetric": {
      "key": "avgMetric",
      "type": "Metric",
      "props": {
        "label": "Avg Order Value",
        "valuePath": "/avgOrderValue",
        "format": "currency"
      }
    },
    "chartCard": {
      "key": "chartCard",
      "type": "Card",
      "props": { "title": "Monthly Trends", "padding": "md" },
      "children": ["chart"]
    },
    "chart": {
      "key": "chart",
      "type": "Chart",
      "props": {
        "type": "line",
        "dataPath": "/monthlyData",
        "height": 300
      }
    }
  },
  "data": {
    "revenue": 284500,
    "orders": 1247,
    "avgOrderValue": 228,
    "monthlyData": [
      { "month": "Jan", "value": 18000 },
      { "month": "Feb", "value": 22000 },
      { "month": "Mar", "value": 28000 },
      { "month": "Apr", "value": 24000 },
      { "month": "May", "value": 32000 }
    ]
  }
}

Then wrap in the artifact template from assets/template.html.

Files

• assets/template.html — Complete artifact template with embedded renderer
• assets/catalog.json — Machine-readable component schemas
• references/uitree-format.md — Detailed UITree specification