Research and create a Shopify theme development rule

You are researching Shopify Liquid patterns to produce a well-documented rule for AI consumption. The topic is: $ARGUMENTS

Read the reference files in this skill's directory before starting:

• references/existing-coverage.md -- what Shopify's cursor rules already cover (avoid duplicating)
• references/theme-guide.md -- recommended themes and how to search them
• references/rule-template.md -- the format every rule must follow

Phase 1 -- Scope

1. Identify the core topic from $ARGUMENTS. Break it down: what Liquid objects, filters, tags, or Shopify features are involved?
2. Check for overlap using the three-level approach:
   • Read references/existing-coverage.md for a summary of what Horizon's cursor rules cover. If the topic overlaps, note what the existing rules cover and focus on what they do NOT cover (advanced patterns, workarounds, edge cases).
   • Check rules/INDEX.md for rules already written in this repo.
   • If shopify-themes/horizon/ is present, scan its .cursor/rules/ directory for the latest coverage. This takes priority over the static summary in existing-coverage.md.
3. Search rules/ for existing rules on the topic. If a related rule exists, determine whether to extend it or create a new one.
4. Present your scope assessment to the user before proceeding.

Phase 2 -- Research

Search for patterns across the themes in shopify-themes/. Use Explore agents to parallelize the search.

If shopify-themes/ is empty or has few themes, expand web research. The skill can still produce valuable rules from Shopify documentation alone, though cross-theme comparisons will be limited. Suggest the user adds themes for richer research -- see references/theme-guide.md for recommendations.

What to search for

• Snippet files related to the topic (search by filename and content in snippets/ folders)
• Section files that implement related functionality (in sections/ folders)
• Liquid patterns using relevant filters, tags, and objects
• Comments mentioning workarounds, tricks, or explanations (search for terms like "workaround", "hack", "trick", "note:", "important:", "TODO")
• Schema patterns in section {% schema %} blocks that relate to the topic

Where to search

Search all themes in shopify-themes/. See references/theme-guide.md for details on recommended themes and search strategies.

Web research (when appropriate)

By default, focus on local theme research when themes are available. Expand to web research when:

• The user explicitly asks for it or shares links
• The user's topic involves a Shopify feature where official docs would add clarity
• Local themes don't have sufficient examples
• shopify-themes/ is empty

Recommended web sources:

• Shopify Dev Docs -- use the Shopify Dev MCP tool if available, otherwise shopify.dev
• Shopify Community forums at community.shopify.dev
• Links the user provides as additional context

Research output

For each pattern found, record:

• Source: theme name and file path
• Code: the relevant Liquid snippet
• Context: what problem it solves, how it's used in the theme
• Quality: is it clean, hacky, well-commented, production-tested?

Phase 3 -- Analysis

1. Catalog all discovered patterns with source references
2. Compare approaches across themes -- what's common, what varies, what's unique?
3. Rank patterns by:
   • Correctness (does it handle edge cases?)
   • Elegance (is it readable and maintainable?)
   • AI-reproducibility (can an AI agent reliably generate this from a description?)
4. Identify the recommended pattern(s) and note why alternatives are weaker
5. Document edge cases, gotchas, and Liquid quirks relevant to this topic

Present a structured summary of findings to the user. Include code snippets from the most interesting patterns.

Phase 4 -- Draft

Discuss with the user:

• Should this be one rule or multiple rules?
• Should it extend an existing rule?
• What category does it belong in?

Then draft the rule following the template in references/rule-template.md. Key principles:

• Write for AI agents: the rule should help an AI turn a high-level requirement into correct Liquid code. Explain the why behind each line, not just the what.
• Include complete, working examples: don't just describe patterns, show them with full context.
• Document the non-obvious: focus on things an AI wouldn't know from Liquid docs alone -- workarounds, quirks, community conventions.
• Be precise about Liquid limitations: if a pattern exists because Liquid can't do something natively, say so explicitly.
• Reference source themes: include where the pattern was found so the user can verify.

Present the draft to the user for review. Iterate based on feedback.

Phase 5 -- Finalize

1. Write the rule file(s) to rules/<category>/<rule-name>.md
   • Use kebab-case for filenames
   • Choose the most appropriate category from the recommended categories (see README or references/rule-template.md)
   • Create the category folder if it doesn't exist yet
2. Update rules/INDEX.md:
   • Add the new rule under the appropriate category heading in the Rules section
   • Format: - [Rule Title](category/rule-name.md) -- one-line description
3. If this topic came from rules/BACKLOG.md, update the corresponding entry's status to done and add the rule link
4. Suggest related topics that could become future rules based on what you discovered during research

Important guidelines

• Never invent Liquid filters, tags, or objects. Only use what exists in Shopify's Liquid implementation.
• When showing code examples, use the {% liquid %} tag for multiline logic blocks (Shopify convention for newer themes).
• Always test that code examples are syntactically valid Liquid.
• If a pattern involves metafields, specify the metafield namespace and type clearly.
• Cross-reference Shopify's official Liquid docs when unsure about object properties or filter behavior.