Preload item associations in ClosureRepository::findByNavigation

[tannyl]

Problem

ClosureRepository::findByNavigation() joins the descendant Item purely for filtering; it does not addSelect() or fetch-join any of the item's associations. As a result:

• GraphBuilder::build() calls $closure->getDescendant(), $closure->getAncestor(), and $descendant->hasChannel() for every closure — each triggers a lazy load.
• Rendering templates then call $node.item.label (translation lookup: LIMIT 1 + all + COUNT) and, for TaxonItem, $node.item.taxon and $taxon.name/.slug (taxon + taxon translation) — again lazy per item.

The result is a classic N+1 that scales linearly with menu size. On a store with 732 navigation items, rendering the megamenu issued 5170 database queries per request (query time 570 ms) — verified against the real production data
set. CachedNavigationRenderer masks this in production most of the time, but the cost is paid on every cold cache (deploy, cache clear, or when the invalidation listeners fire after any admin edit) and on every dev request (where the
cache is off by default).

Fix

Preload the associations in findByNavigation():

1. Fetch closures with descendant and ancestor Items in the main query (addSelect('item', 'ancestor') plus join('o.ancestor', 'ancestor')).
2. Run separate preload queries for item.translations, item.channels, and TaxonItem.taxon + taxon.translations. The results attach to the already-hydrated Items via the Doctrine identity map.

Splitting into multiple queries (rather than fetch-joining everything in the main query) avoids the cartesian product of closures × item.translations × item.channels × taxon.translations that would otherwise blow up the result set.

Impact

Measured on the same 732-item menu after the patch:

	Before	After
Database queries	5170	130
Query time	570 ms	53 ms
Managed entities	4758	4898

Same rows/columns are retrieved end-to-end — only the round-trip count changes. A small over-fetch (~3 %) occurs because associations are now preloaded for every item in the navigation, including items that GraphBuilder later filters
out (disabled, wrong channel, or excluded ancestor). Negligible in practice.

Cold-cache first-render cost drops from ~570 ms to ~50 ms, which also makes the postUpdate/postPersist/postRemove cache invalidations from ItemBasedNavigationCacheInvalidatorListener and
TaxonBasedNavigationCacheInvalidatorListener non-painful.

Tests

Existing it_finds_closures_by_navigation continues to pass (return contract unchanged). Added it_preloads_item_associations_when_finding_by_navigation — after findByNavigation() + EntityManager::clear(), verifies that the
descendant Item, its translations collection, channels collection, TaxonItem.taxon, and taxon.translations are all initialized (no lazy proxies, PersistentCollection::isInitialized() returns true).

Local run:

• composer check-style ✓
• vendor/bin/rector process --dry-run ✓
• composer analyse ✓
• composer phpunit -- --testsuite=unit — 289 tests ✓
• composer phpunit -- --testsuite=functional — 37 tests ✓ (was 36 + 1 new)