Cloudflare Images URL transformation broken when variant already present

[ascorbic]

Problem

When a Cloudflare Images URL already has a variant/transforms in the path, Unpic generates malformed srcset URLs.

Input URL

https://imagedelivery.net/5LGXGUnHU18h6ehN_xjpXQ/abc123/public

or with transforms:

https://imagedelivery.net/5LGXGUnHU18h6ehN_xjpXQ/abc123/w=1200,fit=scale-down

Output (broken)

https://imagedelivery.net/5LGXGUnHU18h6ehN_xjpXQ/abc123/public=undefined,w=640,h=480,fit=cover 640w

The =undefined is clearly wrong, and it's appending to the existing variant instead of replacing it.

Expected

Either:

1. Replace the existing variant with the new transforms
2. Or detect that transforms are already present and skip transformation

Working case

When the URL has no variant, it works correctly:

// Input
https://imagedelivery.net/5LGXGUnHU18h6ehN_xjpXQ/abc123

// Output (correct)
https://imagedelivery.net/5LGXGUnHU18h6ehN_xjpXQ/abc123/w=640,h=480,fit=cover 640w

Workaround

We're currently stripping the variant from URLs before passing to Unpic and using the base URL only.

Version

@unpic/core 1.0.3

[ascorbic]

Actually, there's a more fundamental issue: Cloudflare Images URLs require a variant - the base URL without one returns 400:

# Returns 400
curl -I "https://imagedelivery.net/hash/image-id"

# Returns 200
curl -I "https://imagedelivery.net/hash/image-id/public"
curl -I "https://imagedelivery.net/hash/image-id/w=800"

So Unpic can't use the base URL directly - it needs to know to always append a variant path segment.

The URL structure is:

https://imagedelivery.net/{account_hash}/{image_id}/{variant}

Where {variant} can be:

• A named variant like public, thumbnail
• Flexible transforms like w=800,h=600,fit=cover

When Unpic receives a URL with an existing variant (like /public), it seems to try to append transforms incorrectly. When it receives a URL without a variant, it creates an invalid URL that returns 400.