SYP-PRF-002 · v1.2.0 · Published
Theme image without a bounded delivery width
Detects supported image output patterns that do not communicate an appropriate delivery width.
Description
Detects supported image output patterns that do not communicate an appropriate delivery width.
Why it matters
An unbounded image request can transfer more image data than the rendered layout requires.
Detection
The Runtime inspects supported Liquid image URL and image tag patterns, then checks whether responsive dimensions or a bounded width are present.
Does not match
- Supported image_url expressions with an explicit bounded width
- Non-image Liquid objects
- Image delivery produced entirely by an external application
Evidence
- Image output expression
- Requested width or missing width parameter
- Rendered markup pattern and source location
Validation
The candidate is accepted when a supported Shopify image expression can request an unbounded delivery size and the surrounding supported markup provides no bounded alternative.
Examples
{{ product.featured_image | image_url }}{{ product.featured_image | image_url: width: 1200 }}Examples document the rule contract. A safer direction is not an automatic apply instruction and still requires review in the complete theme context.
Limitations
- The rule does not measure real-user performance.
- The correct width depends on layout and device requirements.
- Images delivered by apps or external scripts may not be visible to theme analysis.
References
Compatibility
Supported
- Shopify Liquid themes
- Shopify-hosted image objects
- Supported image_url patterns
Not established
- Measured Core Web Vitals
- External image CDNs and app-rendered media
- Whether a chosen width is visually correct for every breakpoint