Media: Add JPEG XL (JXL) upload support (backport GB #77584) - #12006

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# Conflicts:
#	src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php

…back

# Conflicts:
#	src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php

Extends the /wp/v2/media/<id>/sideload route so the client-side media
flow can upload a HEIC/HEIF companion original alongside the JPEG
derivative:

- Adds 'original-heic' to the allowed image_size enum. The companion
  filename is recorded under $metadata['original'] so it never
  collides with 'original_image', which the scaled-sideload flow owns.
- Adds a 'generate_sub_sizes' boolean arg (default false) so callers
  that handle processing client-side can suppress server-side sub-size
  generation per request.
- Adds 'image/heif' to the image_output_formats input list returned by
  the REST API root index.

Backport of GB #76731.

When the client-side media flow sideloads a HEIC original alongside a
JPEG derivative, the HEIC filename is stored in $metadata['original'].
wp_delete_attachment_files() only tracks 'original_image', so without
this hook the HEIC file would linger on disk after the attachment is
removed.

wp_delete_attachment_heic_companion_file() reads the meta key, guards
against non-string values (e.g. arrays written by other flows), and
deletes the file when present. Hooked into the delete_attachment
action via default-filters.php.

Backport of GB #76731, with the is_string() guard from GB #78128.

Adds REST API controller tests:
- The sideload route exposes 'original-heic' in the image_size enum.
- The sideload route exposes a 'generate_sub_sizes' boolean arg
  defaulting to false.
- Sideloading an 'original-heic' image writes the filename to
  $metadata['original'] and leaves 'original_image' untouched.

Adds wp_delete_attachment_heic_companion_file() unit tests:
- The companion HEIC is removed when the attachment is deleted.
- The hook is a no-op when $metadata['original'] is missing.
- The hook bails when $metadata['original'] is not a string
  (regression coverage for the guard added in GB #78128).

…deload.

The test was sending JPEG bytes with a .heic filename, which wp_check_filetype_and_ext() corrected to canola-1.jpg before the metadata assertion ran. Switch to the real test-image.heic fixture, set Content-Type accordingly, and pass convert_format=false to disable the default HEIC -> JPEG output mapping so the .heic extension is preserved.

Add 'original-heic' to the image_size enum and the missing generate_sub_sizes arg so the schema fixture matches what the live REST index now reports. Without this the test-fixtures step fails the git diff --exit-code check.

…rvation.

Add server-side support for the client-side media flow that decodes
JPEG XL uploads to JPEG in the browser via lazy-loaded VIPS/WASM and
preserves the original .jxl as a companion file (under
$metadata['original'], the same slot the HEIC companion uses).

* Register `image/jxl` as an allowed upload MIME type. WordPress core
  does not include JXL in its default MIME list, so without this filter
  the editor's allowed-types check rejects the original .jxl before it
  can be converted.

* Add `wp_is_jxl_file()`, a magic-bytes check that recognizes both JXL
  flavors (the naked codestream beginning 0xFF 0x0A and the 12-byte
  ISOBMFF container signature).

* Add `wp_filter_jxl_filetype_and_ext` on `wp_check_filetype_and_ext`.
  PHP's fileinfo reports JXL as `image/x-jxl` (and getimagesize() can't
  identify it at all), so core's MIME-mismatch check otherwise rejects
  the upload. When the file is genuinely JXL, restore the expected
  ext/type so the upload is allowed.

* Accept `original-jxl` as a sideload `image_size`. The branch is
  collapsed with `original-heic` since both write to
  $metadata['original'] and are mutually exclusive.

* Rename `wp_delete_attachment_heic_companion_file()` to
  `wp_delete_attachment_preserved_original_companion_file()` since the
  same hook now covers both HEIC and JXL companions. The implementation
  is unchanged; only the name and docblock are generalized. The test
  file is renamed alongside.

Backport of WordPress/gutenberg#77584. Stacked on WordPress#11323 (HEIC canvas
fallback).

Nothing in sideload_item() reads it - the only readers are create_item()
and its permissions check, which use the argument registered by
get_endpoint_args_for_item_schema(). Trunk now asserts the sideload route
does not advertise it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AGarM6qGwHbEknVuo9tTHS

The blanket bypass also covered image/heic-sequence and
image/heif-sequence, which trunk asserts must stay rejected because
neither the server nor the client fallback can handle them. The
still-image bypass belongs to its own backport, WordPress#13042.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AGarM6qGwHbEknVuo9tTHS

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AGarM6qGwHbEknVuo9tTHS

The branch adds image_output_formats to the REST index; the entry was
lost while resolving the trunk merge in wp-api-generated.js.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AGarM6qGwHbEknVuo9tTHS

Core also empties the type when image/jxl is not an allowed MIME type, so
restoring it whenever the type was empty let JXL uploads through on sites
that removed it, such as a network whose upload file types leave it out.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AcYRm3egtiB9yfX1VFaatb

7.2 is in beta, so the JXL support lands in the next release.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AcYRm3egtiB9yfX1VFaatb

Gutenberg now keeps a JXL upload in its own format and generates its sub-sizes as JXL in the browser, instead of converting it to JPEG. That needs the server to know the image's size, which getimagesize() cannot read for JXL. Teach wp_getimagesize() to read it from the codestream header, and build attachment metadata for image/jxl, so core reports the missing sub-sizes and the sideload endpoint accepts them.

Also register JXL ahead of check_upload_mimes(), leave untyped arguments in the filetype filter alone, and have wp_is_jxl_file() share the codestream reader.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017uBiB3PfgBJpX6dbD1mN4B