diff --git a/CHANGELOG.md b/CHANGELOG.md
index e56e1532..1cb12a37 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.16.1] - 2026-06-01
+
+### Fixed
+- Fix multi-embed cache dependency: a `#[Cacheable]` resource embedding more than one child kept only the last child's dependency, so purging an earlier child failed to invalidate the parent (stale cache). `CacheDependency::depends()` now accumulates child tags instead of overwriting, and the erroneous assertion that a parent had no prior tags has been removed.
+
 ## [1.16.0] - 2026-05-16
 
 ### Fixed
diff --git a/src/CacheDependency.php b/src/CacheDependency.php
index e1fb9a1b..eb79aba2 100644
--- a/src/CacheDependency.php
+++ b/src/CacheDependency.php
@@ -7,7 +7,6 @@
 use BEAR\Resource\ResourceObject;
 use Override;
 
-use function assert;
 use function sprintf;
 
 final readonly class CacheDependency implements CacheDependencyInterface
@@ -20,14 +19,17 @@ public function __construct(
     #[Override]
     public function depends(ResourceObject $from, ResourceObject $to): void
     {
-        assert(! isset($from->headers[Header::SURROGATE_KEY]));
-
-        $cacheDependencyTags = ($this->uriTag)($to->uri);
+        $childTags = ($this->uriTag)($to->uri);
         if (isset($to->headers[Header::SURROGATE_KEY])) {
-            $cacheDependencyTags .= sprintf(' %s', $to->headers[Header::SURROGATE_KEY]);
+            $childTags .= sprintf(' %s', $to->headers[Header::SURROGATE_KEY]);
             unset($to->headers[Header::SURROGATE_KEY]);
         }
 
-        $from->headers[Header::SURROGATE_KEY] = $cacheDependencyTags;
+        // Accumulate across every embedded child: a resource that embeds more than one
+        // child must depend on all of them, not only the last. Overwriting here used to
+        // silently drop earlier children's dependencies (stale-cache bug).
+        $from->headers[Header::SURROGATE_KEY] = isset($from->headers[Header::SURROGATE_KEY])
+            ? sprintf('%s %s', $from->headers[Header::SURROGATE_KEY], $childTags)
+            : $childTags;
     }
 }
diff --git a/tests/ComplexCacheDependencyTest.php b/tests/ComplexCacheDependencyTest.php
new file mode 100644
index 00000000..400354ad
--- /dev/null
+++ b/tests/ComplexCacheDependencyTest.php
@@ -0,0 +1,115 @@
+<?php
+
+declare(strict_types=1);
+
+namespace BEAR\QueryRepository;
+
+use BEAR\Resource\ResourceInterface;
+use BEAR\Resource\Uri;
+use PHPUnit\Framework\TestCase;
+use Ray\Di\Injector;
+
+/**
+ * Stress test for the cache dependency resolution with a DIAMOND graph.
+ *
+ *            diamond-top
+ *            /         \
+ *     diamond-left   diamond-right
+ *            \         /
+ *           diamond-bottom
+ *
+ * `diamond-top` embeds BOTH `diamond-left` and `diamond-right` (multi-embed);
+ * each arm embeds the shared leaf `diamond-bottom`. This exercises cases the
+ * existing chain / single-embed fixtures never reach:
+ *  - a parent that embeds more than one child (multi-embed accumulation),
+ *  - a leaf reachable through two independent paths,
+ *  - precise (non-over-reaching) invalidation of a single arm.
+ */
+class ComplexCacheDependencyTest extends TestCase
+{
+    private ResourceInterface $resource;
+    private QueryRepositoryInterface $repository;
+
+    protected function setUp(): void
+    {
+        $injector = new Injector(new FakeEtagPoolModule(ModuleFactory::getInstance('FakeVendor\HelloWorld')), __DIR__ . '/tmp');
+        $this->resource = $injector->getInstance(ResourceInterface::class);
+        $this->repository = $injector->getInstance(QueryRepositoryInterface::class);
+
+        parent::setUp();
+    }
+
+    private function isCached(string $name): bool
+    {
+        return $this->repository->get(new Uri('page://self/dep/' . $name)) instanceof ResourceState;
+    }
+
+    public function testDiamondBuildsEveryNode(): void
+    {
+        $this->resource->get('page://self/dep/diamond-top');
+
+        foreach (['diamond-top', 'diamond-left', 'diamond-right', 'diamond-bottom'] as $name) {
+            $this->assertTrue($this->isCached($name), $name . ' should be cached after the build');
+        }
+    }
+
+    public function testMultiEmbedParentDependsOnEveryChild(): void
+    {
+        // Regression: diamond-top embeds BOTH arms. Purging EITHER arm must invalidate top.
+        // Before the fix, the second embed overwrote the first, so one arm's dependency was lost.
+        $this->resource->get('page://self/dep/diamond-top');
+        $this->repository->purge(new Uri('page://self/dep/diamond-left'));
+        $this->assertFalse($this->isCached('diamond-top'), 'top must depend on its LEFT child');
+
+        $this->resource->get('page://self/dep/diamond-top'); // rebuild
+        $this->repository->purge(new Uri('page://self/dep/diamond-right'));
+        $this->assertFalse($this->isCached('diamond-top'), 'top must also depend on its RIGHT child');
+    }
+
+    public function testPurgingSharedLeafCascadesThroughBothPaths(): void
+    {
+        $this->resource->get('page://self/dep/diamond-top');
+
+        // diamond-bottom is embedded via both arms; purging it invalidates every ancestor.
+        $this->repository->purge(new Uri('page://self/dep/diamond-bottom'));
+
+        $this->assertFalse($this->isCached('diamond-top'), 'top reaches bottom via both arms');
+        $this->assertFalse($this->isCached('diamond-left'), 'left embeds bottom');
+        $this->assertFalse($this->isCached('diamond-right'), 'right embeds bottom');
+    }
+
+    public function testPurgingOneArmIsPreciseAndDoesNotOverReach(): void
+    {
+        $this->resource->get('page://self/dep/diamond-top');
+
+        // Purge only the left arm.
+        $this->repository->purge(new Uri('page://self/dep/diamond-left'));
+
+        $this->assertFalse($this->isCached('diamond-top'), 'top embeds left -> invalidated');
+        $this->assertTrue($this->isCached('diamond-right'), 'the right arm is independent of left');
+        $this->assertTrue($this->isCached('diamond-bottom'), 'the shared leaf survives an arm purge');
+    }
+
+    public function testRebuildAfterPurgeRePropagatesDependencies(): void
+    {
+        $this->resource->get('page://self/dep/diamond-top');
+        $this->repository->purge(new Uri('page://self/dep/diamond-bottom'));
+        $this->assertFalse($this->isCached('diamond-top'), 'cascade invalidated top');
+
+        // Rebuild and confirm the dependency graph is restored (not a one-shot).
+        $this->resource->get('page://self/dep/diamond-top');
+        $this->assertTrue($this->isCached('diamond-top'));
+        $this->repository->purge(new Uri('page://self/dep/diamond-bottom'));
+        $this->assertFalse($this->isCached('diamond-top'), 'cascade still works after a rebuild');
+    }
+
+    public function testUnrelatedResourceIsUnaffectedByDiamondPurges(): void
+    {
+        $this->resource->get('page://self/dep/diamond-top');
+        $this->resource->get('page://self/dep/child-c'); // unrelated chain
+
+        $this->repository->purge(new Uri('page://self/dep/diamond-bottom'));
+
+        $this->assertTrue($this->isCached('child-c'), 'an unrelated resource must not be touched');
+    }
+}
diff --git a/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondBottom.php b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondBottom.php
new file mode 100644
index 00000000..effa9d20
--- /dev/null
+++ b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondBottom.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace FakeVendor\HelloWorld\Resource\Page\Dep;
+
+use BEAR\RepositoryModule\Annotation\Cacheable;
+use BEAR\Resource\ResourceObject;
+
+#[Cacheable]
+class DiamondBottom extends ResourceObject
+{
+    public $body = ['diamond-bottom' => 1];
+
+    public function onGet()
+    {
+        return $this;
+    }
+}
diff --git a/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondLeft.php b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondLeft.php
new file mode 100644
index 00000000..184f4de1
--- /dev/null
+++ b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondLeft.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace FakeVendor\HelloWorld\Resource\Page\Dep;
+
+use BEAR\RepositoryModule\Annotation\Cacheable;
+use BEAR\Resource\Annotation\Embed;
+use BEAR\Resource\ResourceObject;
+
+#[Cacheable]
+class DiamondLeft extends ResourceObject
+{
+    public $body = ['diamond-left' => 1];
+
+    #[Embed(rel: 'bottom', src: '/dep/diamond-bottom')]
+    public function onGet()
+    {
+        return $this;
+    }
+}
diff --git a/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondRight.php b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondRight.php
new file mode 100644
index 00000000..8923ad7c
--- /dev/null
+++ b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondRight.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace FakeVendor\HelloWorld\Resource\Page\Dep;
+
+use BEAR\RepositoryModule\Annotation\Cacheable;
+use BEAR\Resource\Annotation\Embed;
+use BEAR\Resource\ResourceObject;
+
+#[Cacheable]
+class DiamondRight extends ResourceObject
+{
+    public $body = ['diamond-right' => 1];
+
+    #[Embed(rel: 'bottom', src: '/dep/diamond-bottom')]
+    public function onGet()
+    {
+        return $this;
+    }
+}
diff --git a/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondTop.php b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondTop.php
new file mode 100644
index 00000000..d9fa950f
--- /dev/null
+++ b/tests/Fake/fake-app/src/Resource/Page/Dep/DiamondTop.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace FakeVendor\HelloWorld\Resource\Page\Dep;
+
+use BEAR\RepositoryModule\Annotation\Cacheable;
+use BEAR\Resource\Annotation\Embed;
+use BEAR\Resource\ResourceObject;
+
+#[Cacheable]
+class DiamondTop extends ResourceObject
+{
+    public $body = ['diamond-top' => 1];
+
+    #[Embed(rel: 'left', src: '/dep/diamond-left')]
+    #[Embed(rel: 'right', src: '/dep/diamond-right')]
+    public function onGet()
+    {
+        return $this;
+    }
+}