Recover image dimensions when base metadata is incomplete (1x1 WebP)

[adamsilverstein]

Summary

Addresses the intermittent "1×1 px WebP" bug reported in #2468.

Root cause

The reporter's stored metadata for a broken attachment contained only the keys added by the performance plugins and none of the base metadata that core normally produces:

array(
  'dominant_color'   => '757863',
  'has_transparency' => false,
  'sources'          => array( 'image/webp' => array( ... ) ),
)

No width, height, file, or sizes. That happens when core's wp_create_image_subsizes() bails early:

$imagesize = wp_getimagesize( $file );
if ( empty( $imagesize ) ) {
    return array(); // no width/height/sizes
}

wp_getimagesize() can fail intermittently at upload time (e.g. the file is read before it has finished being written to disk). Core then returns an empty array, the wp_generate_attachment_metadata filters decorate it, and the incomplete record is persisted. With width/height missing, core's wp_constrain_dimensions() clamps the dimensions to max( 1, 0 ) = 1, which is why the image renders at 1×1 in the Media Library grid and in the front-end HTML, even though the file itself opens fine. This also explains the "random / works on re-upload" behavior: re-uploading creates a fresh attachment that usually processes cleanly.

The change

By the time webp_uploads_create_sources_property() runs, the file is readable again (the sources and dominant_color keys prove the file was read successfully a moment later). So when the base metadata is missing its dimensions, the filter now recovers width/height from the file before attaching the sources property. If the file still can't be read, it bails without inventing dimensions or persisting a partial record.

This restores correct display of the full-size image. Responsive sub-sizes (sizes) are still absent in this failure case and require regenerating the attachment (wp media regenerate <id>).

Why only the webp-uploads plugin

dominant-color-images is intentionally designed to extract the dominant color independently of base metadata (see test-dominant-color.php, which asserts the color is added even when the incoming metadata is array()). The dominant_color key in the corrupted record is a witness, not a cause, so that plugin is left unchanged.

Testing

• test_it_should_recover_dimensions_when_base_metadata_is_incomplete — passes incomplete metadata and asserts the real dimensions are recovered and sources attached.
• test_it_should_not_decorate_metadata_when_file_is_missing — asserts no dimensions are invented and no sources added when the file can't be read.

Open questions / follow-ups

• This is a mitigation at the plugin layer. The underlying trigger is core returning empty metadata on an intermittent wp_getimagesize() failure; a more complete fix (retry, or regenerating sub-sizes) may warrant a core Trac ticket.
• Draft pending a green CI run of the new tests.

Refs #2468

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 69.90%. Comparing base (ea77bb1) to head (1728208).
⚠️ Report is 151 commits behind head on trunk.

Files with missing lines	Patch %	Lines
plugins/webp-uploads/hooks.php	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #2542      +/-   ##
==========================================
+ Coverage   69.87%   69.90%   +0.03%     
==========================================
  Files          90       90              
  Lines        7797     7803       +6     
==========================================
+ Hits         5448     5455       +7     
+ Misses       2349     2348       -1     

Flag	Coverage Δ
multisite	69.90% <83.33%> (+0.03%)	⬆️
single	35.31% <16.66%> (-0.02%)	⬇️

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