Fix: interactivity-router preserve dynamically-injected and deferred stylesheets across navigations - #76289

…WordPress#76289)

Three new test cases covering the two bugs fixed in the previous commit.

areNodesEqual — media mismatch treated as equal:
Verifies that a <link> with media="all" and a <link> with media="not all" but the same href and integrity are treated as the same element by the SCS comparator, and that the live DOM element is reused rather than replaced.

areNodesEqual — integrity difference still discriminates:
Confirms that other attributes (integrity) still differentiate elements, ensuring the media-stripping does not over-broaden equality.

applyStyles — dynamically-injected plugin styles never disabled:
Verifies that a <link> without an id attribute, injected via appendChild(), is never disabled on any navigation cycle.

applyStyles — plugin styles not enrolled on A→B→C→A back-navigation:
Verifies that, on return to a cached page whose page.styles snapshot includes the plugin element, applyStyles() does not enroll the plugin element in routerManagedStyles and does not disable it on the subsequent navigation away.

Also updates the existing "should enable included styles and disable others" test to reflect the new enrollment-on-activation model: elements must pass through media="preload" activation before they become candidates for disabling.

Three Playwright tests covering real-browser behavior across all
navigation paths, registered via the test/router-dynamic-styles block.

- runtime-activated deferred stylesheet survives forward navigation
(Bug A: media="not all" → "all" preserved after navigate())

- plugin-injected stylesheet survives forward navigation 
(Bug B: no-id element stays active after navigate())

- plugin-injected stylesheet survives back-navigation A→B→C→A
(Bug B cache regression: cached page.styles may include the plugin element; verifies it is not enrolled and not disabled on re-visit)

Reformat seven expect() chains so the argument sits inline with expect() and the assertion value moves to the next line, matching prettier's preferred style for chained matchers.

No logic change.

Add block.json to register the test/router-dynamic-styles block used by router-dynamic-styles.spec.ts E2E fixtures. Declares viewScriptModule pointing to view.js and render callback pointing to render.php.

Add view.js with the @wordpress/interactivity store for the
test/router-dynamic-styles E2E fixture block.

Implements two style-scenario fixtures:

Bug A: activateDeferredStyle action mutates link.media from "not all"
to "all". The init callback reads --test-deferred-active via
getComputedStyle to verify the sheet survived navigation.

Bug B: init callback appends a <style> element without an id attribute,
simulating plugins like Complianz GDPR that bypass wp_enqueue_style().
sheet.disabled is checked directly after each navigation to confirm
the router never enrolled or disabled this element.

pluginStyleEl is module-scoped so it persists across SPA navigations
without relying on store-state serialisation.

Add render.php for the test/router-dynamic-styles E2E fixture block.

Enqueues deferred-style.css with media="not all" to simulate Bug A
(runtime-activated deferred stylesheets). Resolves sibling post URLs
by alias suffix (-b, -c) matching the titles set by addPostWithBlock,
and outputs all data-testid elements required by the spec:
deferred-style-active, plugin-style-active, activate-deferred-style,
nav-to-b, and nav-to-c.

Remove unused 'actions' and 'callbacks' destructuring from store() call. Collapse two ternary expressions onto single lines to satisfy prettier.

Collapse pluginStyleEl.textContent assignment onto a single line.
Merge the split boolean condition in pluginStyleStatus onto one line
to match prettier's expected formatting.

…view

Remove 'actions' and 'callbacks' from the store() destructuring assignment.
Both are registered implicitly by passing them to store() and do not need
to be captured in variables, so ESLint correctly flagged them as unused.

…tyle, use direct sheet checks

Root cause: init() used getComputedStyle to detect deferred stylesheet
activation via a CSS custom property. This approach fails silently when
deferred-style.css returns ERR_FAILED (404/network error in CI) — the
property is always "" and init() unconditionally overwrites
state.deferredStyleStatus back to "inactive" on every re-run, racing
against the action that just set it to "active".

Changes:
- Remove getComputedStyle entirely. deferredStyleStatus is now set only
  from activateDeferredStyle() (immediate click feedback) and from
  init() on re-navigation via link.sheet.disabled (direct DOM check).
- Introduce a plain module-level `deferredActivated` boolean instead of
  reactive state. Reading a non-reactive variable inside a callback does
  not create a reactive subscription, so init() cannot be re-triggered
  by the action's state mutation.
- Null-safe link.sheet handling: if the CSS file fails to load the
  browser sets sheet to null. Fall back to link.media !== "not all" as
  the activation signal (the router can only disable via sheet.disabled,
  not by reverting media).
- Bug B detection unchanged in logic; inline <style> elements always
  have a .sheet after appendChild in modern browsers.

…styles view

ESLint no-nested-ternary flagged the combined sheet/media
assignment. Split into an if/else block with a flat ternary on
each branch. No logic change.

…ule dependency

WordPress Script Modules reads {module}.asset.php to build the page
import map. Without this file @wordpress/interactivity has no map entry,
view.js silently fails to load, and all data-wp-init callbacks never run.

Adds data-wp-router-region to the block wrapper in render.php so the iAPI router intercepts link clicks and performs SPA navigation. Without this directive the router is inactive and every link click causes a full page reload, which resets module-level state and makes the deferred-stylesheet test scenario unreliable.

 Bug A and Bug B

Splits the single unreleased changelog entry into two separate lines — one for the deferred stylesheet fix (areNodesEqual media attribute comparison) and one for the dynamically-injected stylesheet fix (applyStyles enrollment gate). No functional changes.

…, not reference

applyStyles() used styles.includes(el) (reference equality). The router caches page.styles as Y-elements from the fetched document, while the live DOM holds original X-element references — different JavaScript objects. A runtime-activated deferred stylesheet (media="not all" → "all") would fail the reference check, causing routerManagedStyles to disable it on every navigation. Fix: pre-normalise the styles list once, then fall back to normalised equivalence matching when reference equality misses. Reference check is tried first (O(1)) so there is no performance cost for the common case.

…ManagedStyles seed

Two fixes for regressions in the E2E test run:

1. normalizeMedia: treat media="not all" as "all".
   WordPress uses media="not all" as a load-deferral trick; the intended
   scope is always "all". Without this, the live activated element
   (media="all") and the server-returned element (media="not all") differ
   after normalisation, the SCS algorithm treats them as separate resources,
   the live element is dropped from page.styles, and applyStyles() disables
   the activated sheet — the same Bug A that WordPress#76289 set out to fix.

2. routerManagedStyles: seed from all <link rel="stylesheet"> and <style>
   elements present in the DOM at module init, not just those with [id].
   Block-level <style> tags rendered server-side have no id attribute, so
   the previous [id]-only selector excluded them from the managed set and
   applyStyles() could never disable them, leaving stale styles from
   earlier pages active. Plugin-injected sheets (Complianz, etc.) are
   added via appendChild() after module init, so they are never in the
   initial DOM snapshot and remain unmanaged — Bug B protection intact.

… deferred sheets

applyStyles() matched DOM elements against page.styles using reference
equality (styles.includes(el)). When the router stores Y-elements (fetched
document) in page.styles, the live DOM element — a deferred sheet activated
at runtime (media="not all" → "all") — is a different object reference and
was incorrectly disabled on every navigation.

Add a normalised-equality fallback: pre-normalise the incoming styles list
once (O(N)) and use areNodesEqual() as a secondary check. normalizeMedia()
already treats media="not all" as "all", so the activated live element and
the server-returned element are recognised as the same resource.

- Updates the "deferred stylesheet" test to check the CSS custom property directly.
- This verifies the actual stylesheet state rather than relying on JS state hydration, which is subject to useInit lifecycle limitations.

…yles

utils.getLink() appends ?disable_server_directive_processing=true to
every link it returns (needed for the initial page load), but the SPA
navigation follows the raw permalink href emitted by render.php's
get_permalink() calls, which never carries that query param. The
exact-string toHaveURL() checks added in the previous commit compared
against utils.getLink()'s output, so they failed deterministically on
every navigation click (Playwright-1 shard, 3 failures).

Match the URL by pathname only, via toPathRegExp(), so the query
string is ignored. The initial page.goto() keeps the full link with
the parameter, as only the first load needs it.

The jsdoc/require-param lint rule requires a @PARAM declaration for
the url parameter of the helper introduced in 9bc8075. Document it,
plus the return value, following the repo's JSDoc conventions.