[6.x] Fix entry URIs going stale when a tree file changes on disk

src/Stache/Stores/CollectionEntriesStore.php

@@ -26,6 +26,18 @@ class CollectionEntriesStore extends ChildStore
     protected $collection;
     private bool $shouldBlinkEntryUris = true;
 
+    public function handleFileChanges()
+    {
+        // Entries get their uris, parents and order from the collection trees, so a tree file that
+        // changed on disk has to be picked up before this store's indexes are used. (Each store
+        // only checks once per request, so this can't loop.)
+        if (Stache::isWatcherEnabled() && ! $this->fileChangesHandled && $this->collection()?->hasStructure()) {
+            Stache::store('collection-trees')?->handleFileChanges();
+        }
+
+        parent::handleFileChanges();
+    }
+
     protected function collection()
     {
         return $this->collection ?? Collection::findByHandle($this->childKey);

src/Stache/Stores/CollectionTreeStore.php

@@ -29,6 +29,28 @@ public function getItemFilter(SplFileInfo $file)
         return $collection->hasStructure();
     }
 
+    /**
+     * A tree file changed on disk (a git pull, a deploy, a hand edit) and the watcher picked it up.
+     * Saving a tree through the API updates the entries it affects in the CollectionTreeSaved
+     * listeners, but there's no saved event here, so update the collection's entries directly.
+     * The previous tree is already gone from the cache, so there's no diff to narrow this down.
+     */
+    protected function handleModifiedItem($tree)
+    {
+        if (! $collection = $tree->collection()) {
+            return;
+        }
+
+        $collection->updateEntryParent();
+        $collection->updateEntryOrder();
+
+        // Same conditions as UpdateStructuredEntryUris: a single-depth (orderable) structure
+        // never affects uris, and without a route there are none.
+        if (! $collection->orderable() && $collection->route($tree->locale())) {
+            $collection->updateEntryUris();
+        }
+    }
+
     protected function newTreeClassByPath($path)
     {
         [$site, $handle] = $this->parseTreePath($path);

tests/Stache/FeatureTest.php

@@ -146,6 +146,62 @@ public function it_gets_an_entry_in_structure_by_uri()
         $this->assertEquals('Directors', $entry->title());
     }
 
+    #[Test]
+    public function the_watcher_updates_entry_uris_when_a_tree_file_changes()
+    {
+        config(['statamic.stache.watcher' => true]);
+
+        $path = __DIR__.'/__fixtures__/content/structures/collections/pages.yaml';
+        $original = file_get_contents($path);
+
+        try {
+            $this->assertEquals('/about/board/directors', Entry::find('pages-directors')->uri());
+
+            // Move "directors" from under about/board to the top level, as a git pull or a hand edit would.
+            file_put_contents($path, <<<'YAML'
+tree:
+  -
+    entry: pages-home
+  -
+    entry: pages-about
+    children:
+      -
+        entry: pages-board
+  -
+    entry: pages-directors
+  -
+    entry: pages-blog
+
+YAML);
+            touch($path, time() + 10);
+
+            $this->nextRequest();
+
+            $this->assertEquals('/directors', Entry::find('pages-directors')->uri());
+            $this->assertEquals('pages-directors', Entry::findByUri('/directors')?->id());
+            $this->assertNull(Entry::findByUri('/about/board/directors'));
+        } finally {
+            file_put_contents($path, $original);
+        }
+    }
+
+    /**
+     * What the next request starts with: the cache as it is, nothing memoized in the stores.
+     */
+    private function nextRequest()
+    {
+        \Statamic\Facades\Blink::flush();
+
+        $this->stache->stores()
+            ->flatMap(fn ($store) => $store instanceof \Statamic\Stache\Stores\AggregateStore ? $store->discoverStores() : [$store])
+            ->each(function ($store) {
+                $store->resetMemoizedState();
+                (fn () => $this->fileChangesHandled = false)->call($store);
+            });
+
+        app('stache.indexes')->each->resetMemoizedState();
+    }
+
     #[Test]
     public function it_returns_null_when_cannot_find_entry_by_uri()
     {