Tiled Gallery: add jetpack_skip_photon_domain filter to keep origin image URLs

[enejb]

Proposed changes

The Tiled Gallery always rewrites its image URLs onto the Photon domain (i0.wp.com), because the tiled layout needs images fetched at exact w/h/crop dimensions and Photon is the on-demand resizer that can produce them. On platforms that already have a Photon-equivalent image service built in (notably WordPress VIP), the origin host understands the same ?w=&h=&crop=&resize= query args, so routing through i0.wp.com is redundant/undesirable.

This adds a new opt-in filter, jetpack_skip_photon_domain (boolean, default false). When it returns true, tiled galleries keep the origin image domain and simply append the same resizing query args, instead of sending URLs through Photon.

Reading guide — the change touches every path that builds tiled-gallery image URLs:

• Classic renderer — modules/tiled-gallery/tiled-gallery/tiled-gallery-item.php: the img_src build now branches on the filter. Default = Image_CDN_Core::cdn_url() (Photon); opted-out = add_query_arg( $img_args, $orig_file ) (origin + same args). The filter is documented here (canonical docblock).
• Classic module wrapper — modules/tiled-gallery/tiled-gallery.php: the fallback that force-runs Image_CDN::filter_the_content() when the Image CDN module is off is now skipped when opting out, so origin URLs aren't re-photonized.
• Block server render — extensions/blocks/tiled-gallery/tiled-gallery.php: exposes the flag to the editor JS, and adds a dephotonize_url() helper so pre-existing block content with baked-in i0.wp.com URLs is rewritten back to origin (both the main src and the srcset). The Photon-only ssl arg is dropped on origin URLs.
• Editor initial state — class.jetpack-gutenberg.php: adds skip_photon_domain to Jetpack_Editor_Initial_State.jetpack so the block's save-time JS can read it.
• Block save-time JS — extensions/blocks/tiled-gallery/utils/index.js: new skipPhotonDomain() reader; when true, photonizedImgProps() reuses the existing photonWpcomImage() helper (which already keeps the origin host + appends args — the same behavior VIP already gets).

Deprecated block versions (deprecated/v2, v6) are intentionally left untouched — their save output must byte-match already-saved content or blocks fail validation.

Related product discussion/links

Does this pull request change what data or activity we track or use?

No.

Testing instructions

Enable the filter (e.g. a mu-plugin):

add_filter( 'jetpack_skip_photon_domain', '__return_true' );

• Classic gallery — create a post with [gallery ids="…" type="rectangular"]. With the filter off, view source: <img src> is https://i0.wp.com/…?w=&h=. With it on: the src is the origin host with ?w=&h=&crop=1, and no i0.wp.com remains. (Note: Image_CDN_Core::cdn_url() photonizes even when the Image CDN module is off, so the "off" state shows i0.wp.com regardless of module state.)
• Block, newly inserted — insert a Tiled Gallery block with the filter on and save; the front-end serves origin URLs + query params. The editor preview also uses origin URLs.
• Block, pre-existing content — a block saved with i0.wp.com URLs, filter on → server render rewrites src/srcset to origin.
• Toggle the filter off → everything returns to i0.wp.com (no change to default behavior).

Verified on a Jurassic Ninja site across all of the above.

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (Jetpack), and enable the add/tiled-gallery-skip-photon-filter branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack add/tiled-gallery-skip-photon-filter

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

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Code Coverage Summary

Coverage changed in 5 files.

File	Coverage	Δ%	Δ Uncovered
projects/plugins/jetpack/extensions/blocks/tiled-gallery/tiled-gallery.php	23/439 (5.24%)	-0.19%	15 💔
projects/plugins/jetpack/extensions/blocks/tiled-gallery/utils/index.js	4/53 (7.55%)	-0.79%	5 💔
projects/plugins/jetpack/modules/tiled-gallery/tiled-gallery/tiled-gallery-item.php	0/48 (0.00%)	0.00%	2 ❤️‍🩹
projects/plugins/jetpack/class.jetpack-gutenberg.php	251/541 (46.40%)	-0.09%	1 ❤️‍🩹
projects/plugins/jetpack/modules/tiled-gallery/tiled-gallery.php	0/151 (0.00%)	0.00%	1 ❤️‍🩹

Full summary · PHP report · JS report

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