offset: continue after a negative offset resumes from a different item than on shopify.dev #2132

After a for loop with a negative offset, offset: continue resumes from a different item in this gem than in the renderer behind the shopify.dev Liquid examples.

Repro

{% assign items = '1,2,3' | split: ',' %}
{% for i in items offset: -1 limit: 2 %}{{ i }}{% endfor %}|{% for i in items offset: continue %}{{ i }}{% endfor %}

{% assign items = '1,2,3' | split: ',' %}
{% for i in items offset: -1 %}{{ i }}{% endfor %}|{% for i in items offset: continue %}{{ i }}{% endfor %}

Results

Both engines agree on the first loop: it starts at the first item and still ends at offset + limit, so offset: -1 limit: 2 renders only 1. They disagree on where the second loop resumes.

• Gem: For#collection_segment stores offsets[@name] = from + segment.length with the unclamped from. The cursor becomes -1 + 1 = 0 in the first case and -1 + 3 = 2 in the second. This line has been unchanged since 2008.
• shopify.dev: the cursor behaves as if from were clamped to 0 first, giving 0 + 1 = 1 and 0 + 3 = 3.

Gem results come from Liquid::Template.parse(source).render on Ruby 4.0.1. The shopify.dev results can be reproduced by running the templates in the examples at https://shopify.dev/docs/api/liquid.

Question

Which behavior is intended? If shopify.dev is correct, clamping from for the cursor (for example offsets[@name] = [from, 0].max + segment.length) would align the gem.