Register Abilities for Performance Lab plugins

With increasing the minimum supported version of WordPress to 6.9 (#2354), we can start to make more use of the Abilities API. This will allow for AI agents to more easily configure the plugins, while also making it easier for developers to interface with them via the REST API (/wp-abilities/v1) and via WP-CLI (wp ability), through which Abilities can be automatically exposed.

I asked Claude Code (Opus 4.6) to look at the plugins to propose a list of Abilities. In implementing any of these, ensure that a PR is only targeting one plugin at a time to make it easier to review and to allow multiple contributors to work in parallel.

Claude Analysis

Below is a proposed set of abilities, grouped by plugin. IDs use the convention {plugin-slug}/{verb-noun}. Each category would be registered once via wp_register_ability_category() (e.g. performance-lab), and each plugin's abilities would meta.show_in_rest = true unless noted.

I've biased toward abilities that an AI agent or remote client could plausibly want — read settings, fetch computed data, trigger regeneration, run diagnostics — and skipped pure CRUD that the existing REST API already covers.

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optimization-detective (foundational — most ability-rich)

This is the framework everything else depends on, so it deserves the broadest surface.

ID	Purpose	Input	Output	Permission
optimization-detective/get-url-metrics	Fetch stored URL Metrics for a URL across all viewport groups	url	URL Metric groups (mobile/tablet/desktop), counts, freshness	edit_posts
optimization-detective/get-lcp-element	Get the detected LCP element (XPath, tag, attributes) per viewport group for a URL	url	{ mobile: {...}, tablet: {...}, desktop: {...} }	edit_posts
optimization-detective/get-url-metrics-freshness	Report whether stored metrics are complete/fresh, sample counts, last collected timestamp	url	freshness summary	edit_posts
optimization-detective/clear-url-metrics	Delete URL Metrics for a single URL (force re-collection)	url	success	manage_options
optimization-detective/run-garbage-collection	Manually run the stale URL Metrics GC	–	count deleted	manage_options
optimization-detective/get-current-etag	Return the current detection-script ETag (for cache-busting diagnostics)	–	etag	edit_posts
optimization-detective/get-template-context	Inspect the template/route context that would be assigned to a given URL	url	context slug, query vars	edit_posts

Read-only (meta.readonly: true): get-url-metrics, get-lcp-element, get-url-metrics-freshness, get-current-etag, get-template-context.

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image-prioritizer

Builds on URL Metrics; abilities should expose its derived recommendations.

ID	Purpose
image-prioritizer/get-lcp-image	Return the LCP image (URL, srcset, dimensions, fetchpriority decision) per viewport for a given page URL
image-prioritizer/get-preload-links	Return the <link rel=preload> items that would be injected for a URL
image-prioritizer/get-lazy-load-decisions	Per-image lazy/eager classification for a URL (img + background-image + video poster)
image-prioritizer/get-video-poster-recommendations	Recommended poster sizes per breakpoint for <video> elements on a URL

All read-only.

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embed-optimizer

ID	Purpose
embed-optimizer/get-embed-optimizations	Return per-embed optimization data for a URL: in-viewport status, reserved min-height, DNS-prefetch hosts
embed-optimizer/get-supported-providers	List embed providers the visitor handles (Twitter/X, WordPress, YouTube, etc.)

Read-only.

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auto-sizes

Auto-sizes is largely automatic and has no settings, so abilities are diagnostic.

ID	Purpose
auto-sizes/compute-sizes-attribute	Given an image's block context (alignment, width, ancestor columns), compute the sizes value the plugin would emit
auto-sizes/get-version-status	Report whether the polyfill is active or whether core ≥ 6.7 is handling sizes=auto

Both read-only. The first is genuinely useful as a debugging/agent tool: "why did this image get this sizes value?"

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dominant-color-images

ID	Purpose	Permission
dominant-color-images/get-attachment-color	Return dominant_color and has_transparency for an attachment ID	read
dominant-color-images/compute-attachment-color	Compute (without storing) the dominant color for an attachment — useful for previews	edit_posts
dominant-color-images/regenerate-attachment-color	Recompute and persist dominant color for an attachment (e.g. after the original is replaced)	edit_post (per-attachment)

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webp-uploads

This plugin already has REST shape via rest_prepare_attachment; abilities should expose targeted operations.

ID	Purpose	Permission
webp-uploads/get-attachment-sources	Return the per-size sources map (mime → URL/path/filesize) for an attachment	read
webp-uploads/regenerate-attachment-sources	Regenerate WebP/AVIF derivatives for one attachment	edit_post
webp-uploads/get-format-settings	Read perflab_modern_image_format, perflab_generate_webp_and_jpeg, perflab_generate_all_fallback_sizes, picture-element preference	manage_options
webp-uploads/update-format-settings	Update any of the above	manage_options
webp-uploads/get-server-format-support	Report whether the active image editor supports WebP and AVIF output	manage_options
webp-uploads/get-picture-element-markup	Return the <picture> markup the plugin would emit for an attachment + size	read

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speculation-rules

ID	Purpose	Permission
speculation-rules/get-settings	Return mode, eagerness, authentication from plsr_speculation_rules	manage_options
speculation-rules/update-settings	Update any of those three fields (validated against the same enums the settings UI uses)	manage_options
speculation-rules/get-rules-for-url	Return the speculation-rules JSON the plugin would emit for a given page URL	edit_posts
speculation-rules/get-excluded-paths	Return the URL patterns currently excluded (after plsr_speculation_rules_href_exclude_paths filter)	edit_posts

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view-transitions

ID	Purpose	Permission
view-transitions/get-settings	Read all plvt_view_transitions fields (animation, duration, selectors, admin toggle, override flag)	manage_options
view-transitions/update-settings	Update any of those fields with validation	manage_options
view-transitions/list-available-animations	Enumerate built-in animation slugs (fade, slide-*, swipe-*, wipe-*) with human labels	read
view-transitions/get-theme-support-status	Report whether the active theme declares native view-transition support (so the plugin would defer)	manage_options

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web-worker-offloading

This plugin is on a sunset track, so I'd keep the surface small.

ID	Purpose	Permission
web-worker-offloading/list-offloaded-scripts	List script handles currently flagged with worker => true	manage_options
web-worker-offloading/get-partytown-config	Return the resolved Partytown configuration after the plwwo_configuration filter	manage_options

Read-only.

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performance-lab (umbrella plugin)

These are arguably the most agent-useful, since they let a client orchestrate the whole suite.

ID	Purpose	Permission
performance-lab/list-features	List all known feature plugins with {slug, name, description, active, installed, version}	activate_plugins
performance-lab/get-feature	Detail for one feature slug	activate_plugins
performance-lab/activate-feature	Install (if needed) and activate a feature plugin — wraps the existing features/{slug}:activate REST route	install_plugins
performance-lab/deactivate-feature	Deactivate a feature plugin	activate_plugins
performance-lab/get-server-timing-metrics	Return the Server-Timing metrics that would be emitted for a given URL request	manage_options
performance-lab/run-site-health-checks	Run only the performance-related Site Health audits and return their results in a normalized shape	view_site_health_checks
performance-lab/get-object-cache-dropin-status	Report whether the object-cache drop-in is installed/managed by Performance Lab	manage_options

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Recommended ability categories

Register these once (in performance.php) so each plugin can attach to a shared taxonomy:

• performance-lab — umbrella/feature management
• performance-lab/measurement — URL Metrics, Server-Timing, Site Health (optimization-detective, performance-lab)
• performance-lab/images — auto-sizes, dominant-color-images, image-prioritizer, webp-uploads
• performance-lab/navigation — speculation-rules, view-transitions
• performance-lab/scripts — web-worker-offloading, embed-optimizer

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Cross-cutting design notes

1. URL-shaped inputs. Many of these accept a url argument. The execute callback should normalize via home_url() resolution and reject off-site URLs — otherwise an agent can poke arbitrary hosts through your endpoints.
2. Read-only flag matters. Anything labeled "get-" above should set meta.readonly: true so clients (and the WP AI client) can call them without confirmation prompts.
3. Permission callbacks should mirror existing UI gates — the same caps that protect Settings → Reading should protect speculation-rules/update-settings, etc. Don't loosen them just because abilities feel "lighter" than REST.
4. Schema discipline. Every ability needs a JSON schema for both input_schema and output_schema — this is what makes them callable by AI clients vs. just being yet-another REST endpoint.
5. Where to register. Put each plugin's abilities in its existing hooks.php (or a new abilities.php included from load.php) hooked on wp_abilities_api_init. Categories go on wp_abilities_api_categories_init.

Choose one plugin from the proposed list and start by reading its existing hooks.php or the load.php entry point. Check how wp_abilities_api_init and wp_abilities_api_categories_init are used, then define the requested ability schemas, permissions, and read-only metadata for that plugin. Done means one plugin has its abilities registered and the relevant REST or WP-CLI exposure works.