Exclude imagesrcset links from Link response header#2578
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Responsive image preloads (imagesrcset/imagesizes) can make the Link response header exceed reverse-proxy header size limits, causing intermittent 502s. These links already get an HTML <link rel=preload> tag unconditionally, so exclude them from the Link header and rely on the HTML tag instead. Refs WordPress#2304
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[Plugin] Optimization Detective
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Additional details and impacted files@@ Coverage Diff @@
## trunk #2578 +/- ##
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- Coverage 70.35% 70.31% -0.05%
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Files 91 91
Lines 7867 7858 -9
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- Hits 5535 5525 -10
- Misses 2332 2333 +1
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@westonruter Closing #2572 as a duplicate of this PR. This one fully excludes Ready for review when you have a moment. |
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Summary
Fixes #2304
Relevant technical choices
OD_Link_Collection::get_response_header()now excludes any link withimagesrcsetset (responsive image preloads) from theLink:HTTP response header. These links already get an HTML<link rel="preload" imagesrcset="..." ...>tag unconditionally viaget_html(), so no functionality is lost — the responsive preload just moves to HTML-only delivery.href, e.g. video posters, background images) are unaffected and still go into both the header and the HTML.$context->link_collection->add_link()with attributes; the header/HTML emission choice is made entirely in this one method in Optimization Detective.srcsetvariants can push the combined response header size past common reverse-proxy limits (Nginx/Apache default buffers), causing intermittent 502 Bad Gateway errors — worse for logged-in users where cookies add to the header total.<link rel="preload">elements rather thanLink:response headers.<link>tags to right after<meta charset>/<title>in<head>) is left as a possible follow-up, not included here.How to test
srcset/sizes, ideally long/non-ASCII filename) detected as the LCP element.Link: ...imagesrcset=...entry.<link rel="preload" imagesrcset="..." ...>tag is still present in<head>and the image still loads with priority.Testing already done
npm run phpstan— cleancomposer lint:optimization-detective(phpcs) — cleancoderabbit review --agent— 0 findings on changed filestest-class-od-link-collection.phpcovering the excluded-from-header behaviorUse of AI Tools
Confirmed I've used Claude AI to generate this PR. Claude Code was used for the full workflow: investigating the issue and root cause across
optimization-detectiveandimage-prioritizer, drafting and implementing the fix, updating tests, and running lint/static analysis. I reviewed the diff, the reasoning, and the test changes, and take responsibility for the change as submitted.