storefront_next_site_theming

Guides theming changes (colors, fonts, visual styling) for Storefront Next and validates color combinations for WCAG accessibility. Call this tool first when the user wants to apply brand colors or change the site theme.

Overview

The storefront_next_site_theming tool provides a structured workflow for applying theming to Storefront Next sites:

1. Guidelines - Layout preservation rules, specification compliance, and accessibility requirements
2. Guided Questions - Collects user preferences (colors, fonts, mappings) one at a time
3. WCAG Validation - Automatically validates color contrast when colorMapping is provided

The tool enforces a mandatory workflow: ask questions → validate colors → present findings → wait for confirmation → implement. Never implement theming changes without calling this tool first.

Authentication

No authentication required. This tool operates on local content and returns guidance text.

Requirements:

• --allow-non-ga-tools flag (preview release)
• Storefront Next project (for implementation; tool itself works without project)

Parameters

Parameter	Type	Required	Description
fileKeys	string[]	No	File keys to add to the default set. Custom keys are merged with defaults: theming-questions, theming-validation, theming-accessibility.
conversationContext	object	No	Context from previous rounds. Omit to list available files. See Conversation Context for details.

Conversation Context

When using the tool across multiple turns, provide conversationContext with the following structure:

Field	Type	Description
currentStep	"updating-information" | "validation"	Current step in the workflow
collectedAnswers	object	Previously collected answers. Include colorMapping to trigger automatic WCAG validation.
questionsAsked	string[]	List of question IDs already asked

collectedAnswers can include:

Field	Type	Description
colors	object[]	Extracted colors with hex and optional type
fonts	object[]	Extracted fonts with name and optional type
colorMapping	object	Maps color keys to hex values (for example, lightText, lightBackground, buttonText, buttonBackground). Providing this triggers automatic WCAG contrast validation.

Operation Modes

List Available Files

Call the tool without conversationContext (and without fileKeys) to list loaded theming file keys:

{}

Returns the list of available keys. Default files are always used when conversationContext is provided.

Theming Workflow

When conversationContext is provided, the tool returns guidelines and questions, or validation results when colorMapping is included.

Workflow

Phase 1: Information Gathering

1. First call - Call the tool with conversationContext.collectedAnswers (can be empty {colors: [], fonts: []})
2. Extract - If the user provided colors/fonts in their message, extract and include in collectedAnswers
3. Ask questions - Tool returns questions; ask the user one at a time and collect answers
4. Update - Call the tool again with updated collectedAnswers after each user response

Phase 2: Validation (Mandatory)

1. Construct colorMapping - Map each color to its usage (text, buttons, links, accents) based on user answers
2. Validation call - Call the tool with collectedAnswers.colorMapping to trigger automatic WCAG validation
3. Present findings - Show contrast ratios, WCAG status (AA/AAA/FAIL), and recommendations to the user
4. Wait for confirmation - Do not implement until the user explicitly confirms

Phase 3: Implementation

Only after completing Phases 1 and 2 may you apply theme changes to app.css (or project theme files).

Usage Examples

Example Prompts (Natural Language)

Try these prompts to get started:

Goal	Example prompt
Start theming from scratch	"I want to apply my brand colors to my Storefront Next site. Use the MCP tool to help me."
Validate before implementing	"I have a color scheme ready. Use the MCP tool to validate my colors for accessibility before I implement."
Colors + fonts upfront	"Use these colors: #635BFF (accent), #0A2540 (dark). Font: Inter. Use the MCP tool to guide me through theming."
Check accessibility only	"Use the MCP tool to validate these color combinations for WCAG: light text #333 on background #FFF, button #0A2540 with white text."
Change existing theme	"I want to change my site theme. Use the MCP tool to walk me through the process."
List available content	"What theming files does the MCP tool have? Use the tool to list them."

First Call - Get Guidelines and Questions

I want to apply my brand colors to my Storefront Next site. Use the MCP tool to help me.

Example arguments:

{
  "conversationContext": {
    "collectedAnswers": {"colors": [], "fonts": []}
  }
}

Validation Call - After Constructing colorMapping

After collecting user answers, construct the color mapping and call the tool to validate.

Minimal colorMapping (light theme only):

{
  "conversationContext": {
    "collectedAnswers": {
      "colorMapping": {
        "lightText": "#000000",
        "lightBackground": "#FFFFFF",
        "buttonText": "#FFFFFF",
        "buttonBackground": "#0A2540"
      }
    }
  }
}

Full colorMapping (light + dark theme):

{
  "conversationContext": {
    "collectedAnswers": {
      "colorMapping": {
        "lightText": "#171717",
        "lightBackground": "#FFFFFF",
        "darkText": "#FAFAFA",
        "darkBackground": "#0A0A0A",
        "buttonText": "#FFFFFF",
        "buttonBackground": "#0A2540",
        "linkColor": "#2563EB",
        "accent": "#635BFF"
      }
    }
  }
}

With Pre-Provided Colors

When the user provides colors upfront, extract and include them:

Use these colors: #635BFF (accent), #0A2540 (dark), #F6F9FC (brand), #FFFFFF (light). Use the MCP tool to guide me through theming.

Example arguments:

{
  "conversationContext": {
    "collectedAnswers": {
      "colors": [
        {"hex": "#635BFF", "type": "accent"},
        {"hex": "#0A2540", "type": "dark"},
        {"hex": "#F6F9FC", "type": "brand"},
        {"hex": "#FFFFFF", "type": "light"}
      ]
    }
  }
}

With Pre-Provided Fonts

When the user specifies fonts:

I want to use Inter for body text and Playfair Display for headings. Use the MCP tool to help me theme my site.

Example arguments:

{
  "conversationContext": {
    "collectedAnswers": {
      "colors": [],
      "fonts": [
        {"name": "Inter", "type": "body"},
        {"name": "Playfair Display", "type": "heading"}
      ]
    }
  }
}

Mid-Conversation Update

When the user answers a question and provides new information, merge it into collectedAnswers and call again:

{
  "conversationContext": {
    "collectedAnswers": {
      "colors": [{"hex": "#635BFF", "type": "accent"}],
      "fonts": [],
      "color-1": "primary action buttons",
      "color-2": "links and hover states"
    },
    "questionsAsked": ["color-1", "color-2"]
  }
}

List Available Files (No Context)

Call with empty arguments to list loaded theming file keys:

{}

Returns available keys such as theming-questions, theming-validation, theming-accessibility.

Custom Theming Files

You can add custom theming files via fileKeys or the THEMING_FILES environment variable. Custom files must follow a specific Markdown format so the parser can extract guidelines, questions, and validation rules.

Required heading patterns (use these exact patterns for content to be parsed):

• ## 🔄 WORKFLOW - Workflow steps (numbered 1. Step text)
• ### 📝 EXTRACTION - Extraction instructions
• ### ✅ PRE-IMPLEMENTATION - Pre-implementation checklist
• ## ✅ VALIDATION - Validation rules (with ### A. Color, ### B. Font, ### C. General, ### IMPORTANT)
• ## ⚠️ CRITICAL: Title - Critical guidelines
• ## 📋 Title - Specification rules
• ### What TO Change: / ### What NOT to Change: - DO/DON'T rules (list items with -)

Questions: Lines ending with ? (length > 10) from bullet or numbered lists are extracted. Reference the built-in files in content/site-theming/ for examples.

Rules and Constraints

• colorMapping triggers automatic WCAG validation; colors and fonts arrays are optional when colorMapping is provided
• fileKeys add to the default files; they do not replace them
• Call the tool first before implementing any theming changes; never skip the question-answer or validation workflow
• Theme changes apply to app.css (standalone: src/app.css; monorepo: packages/template-retail-rsc-app/src/app.css)

Output

The tool returns text content that includes:

• Internal instructions - Workflow steps, critical rules, validation requirements
• User-facing response - What to say to the user, questions to ask
• Validation results (when colorMapping provided) - Contrast ratios, WCAG compliance status, recommendations for failing combinations

Requirements

• --allow-non-ga-tools flag (preview release)
• Storefront Next project (for applying theme changes to app.css)

Features

• Mandatory workflow - Ensures questions are asked and validation is performed before implementation
• Automatic WCAG validation - Validates color contrast when colorMapping is provided
• Content-driven - Loads guidance from markdown files (theming-questions, theming-validation, theming-accessibility)
• Layout preservation - Guidelines enforce that only colors, typography, and visual styling change—never layout or positioning

Related Tools

• Part of the STOREFRONTNEXT toolset
• Auto-enabled for Storefront Next projects (with --allow-non-ga-tools)
• Related: storefront_next_development_guidelines - Architecture and coding guidelines

See Also

• STOREFRONTNEXT Toolset - Overview of Storefront Next development tools
• Storefront Next Guide - Storefront Next development guide
• Configuration - Configure project directory