diff --git a/.changeset/interaction-shadow-dom-target.md b/.changeset/interaction-shadow-dom-target.md
new file mode 100644
index 000000000..e4a441111
--- /dev/null
+++ b/.changeset/interaction-shadow-dom-target.md
@@ -0,0 +1,5 @@
+---
+"@solid-primitives/interaction": patch
+---
+
+fix: resolve interact-outside targets across shadow boundaries
diff --git a/packages/interaction/src/index.ts b/packages/interaction/src/index.ts
index baa26fbdf..ddf29e92a 100644
--- a/packages/interaction/src/index.ts
+++ b/packages/interaction/src/index.ts
@@ -282,6 +282,42 @@ export function createHideOutside(options: CreateHideOutsideOptions): void {
   );
 }
 
+/**
+ * The element an event actually originated from.
+ *
+ * `event.target` is retargeted at every shadow boundary the event crosses, so a listener on the
+ * document reports the outermost shadow *host* rather than the element that was interacted with.
+ * `composedPath()[0]` is that element; for an event that crosses no boundary the two are identical,
+ * so this is a no-op outside shadow DOM.
+ */
+function getEventTarget(event: Event): Element | null {
+  const path = typeof event.composedPath === "function" ? event.composedPath() : undefined;
+  const target = path?.[0] ?? event.target;
+
+  return target instanceof Element ? target : null;
+}
+
+/**
+ * `Node.prototype.contains`, but able to see through shadow boundaries.
+ *
+ * `contains` only walks the node tree it is called on, so it answers `false` for a `child` inside a
+ * shadow root — including `document.contains(elementInAShadowRoot)`. When this walk reaches the top
+ * of a shadow tree it continues from that tree's host, answering a containment question about the
+ * *rendered* page rather than about one node tree.
+ */
+function containsComposed(parent: Node, child: Node | null): boolean {
+  let node: Node | null = child;
+
+  while (node) {
+    if (parent === node || parent.contains(node)) return true;
+
+    const root = node.getRootNode();
+    node = root instanceof ShadowRoot ? root.host : null;
+  }
+
+  return false;
+}
+
 /** Detail payload carried by every outside-interaction `CustomEvent`. */
 export type EventDetails<T> = {
   /** The original DOM event that triggered the outside interaction. */
@@ -399,16 +435,20 @@ export function makeInteractOutside<T extends Element>(
     // a *new* instance that opened in that same window — misreporting them
     // as outside interactions on this now-orphaned instance.
     if (!el.isConnected) return false;
-    const target = e.target as Element | null;
-    if (!(target instanceof Element)) return false;
-    if (!ownerDoc.contains(target)) return false;
-    if (el.contains(target)) return false;
+    // Resolved through `composedPath()`, not `e.target`: these listeners are on the document, so an
+    // interaction inside a shadow tree reports that tree's host instead. `el` rendered inside a
+    // shadow root would see every one of its own clicks as the host — an ancestor, not a descendant
+    // — and read them as outside interactions, dismissing itself on pointerdown.
+    const target = getEventTarget(e);
+    if (!target) return false;
+    if (!containsComposed(ownerDoc, target)) return false;
+    if (containsComposed(el, target)) return false;
     return !(options.shouldExcludeElement?.(target) ?? false);
   };
 
   const onPointerDown = (e: PointerEvent) => {
     const handler = () => {
-      const target = e.target as Element | null;
+      const target = getEventTarget(e);
       if (!target || !isEventOutside(e)) return;
 
       target.addEventListener(
@@ -438,7 +478,7 @@ export function makeInteractOutside<T extends Element>(
   };
 
   const onFocusIn = (e: FocusEvent) => {
-    const target = e.target as Element | null;
+    const target = getEventTarget(e);
     if (!target || !isEventOutside(e)) return;
 
     target.addEventListener(
diff --git a/packages/interaction/test/interact-outside.test.ts b/packages/interaction/test/interact-outside.test.ts
index 7cf638f7f..00aec29e2 100644
--- a/packages/interaction/test/interact-outside.test.ts
+++ b/packages/interaction/test/interact-outside.test.ts
@@ -307,4 +307,110 @@ describe("createInteractOutside", () => {
       second.cleanup();
     });
   });
+
+  describe("Shadow DOM", () => {
+    // These listeners live on the document, so an event originating inside a shadow tree is
+    // retargeted to that tree's host before it arrives. A watched element rendered inside a shadow
+    // root would therefore see every one of its own interactions reported as the host — an
+    // *ancestor* of it, not a descendant — so `el.contains(target)` read false and the element
+    // treated its own content as outside. The visible symptom is a popover that dismisses when you
+    // click inside it, and a trigger that closes and immediately reopens.
+    function setupShadowTest(extraProps: Partial<CreateInteractOutsideProps> = {}) {
+      const onFocusOutside = vi.fn();
+      const onPointerDownOutside = vi.fn();
+      const onInteractOutside = vi.fn();
+
+      const host = document.createElement("div");
+      document.body.appendChild(host);
+      const shadowRoot = host.attachShadow({ mode: "open" });
+
+      // A child of the watched element, not the element itself: only a descendant is deep enough
+      // for retargeting to change the answer.
+      const inside = createElement("div", "inside");
+      const insideChild = createElement("div", "inside-child");
+      inside.appendChild(insideChild);
+      shadowRoot.appendChild(inside);
+
+      // A sibling in the same shadow root — genuinely outside, and must stay that way.
+      const outside = createElement("div", "outside");
+      shadowRoot.appendChild(outside);
+
+      const dispose = createRoot(d => {
+        createInteractOutside(
+          { onFocusOutside, onPointerDownOutside, onInteractOutside, ...extraProps },
+          () => inside,
+        );
+        return d;
+      });
+
+      flush();
+      vi.runAllTimers();
+
+      return {
+        mocks: { onFocusOutside, onPointerDownOutside, onInteractOutside },
+        inside,
+        insideChild,
+        outside,
+        cleanup: () => {
+          dispose();
+          host.remove();
+        },
+      };
+    }
+
+    it("does not trigger on pointerdown inside the watched element's own shadow content", () => {
+      const { mocks, insideChild, cleanup } = setupShadowTest();
+
+      insideChild.dispatchEvent(
+        new PointerEvent("pointerdown", { bubbles: true, composed: true, pointerType: "mouse" }),
+      );
+
+      expect(mocks.onPointerDownOutside).not.toHaveBeenCalled();
+      expect(mocks.onInteractOutside).not.toHaveBeenCalled();
+      cleanup();
+    });
+
+    it("does not trigger when focus moves into the watched element's own shadow content", () => {
+      const { mocks, insideChild, cleanup } = setupShadowTest();
+
+      insideChild.dispatchEvent(new FocusEvent("focusin", { bubbles: true, composed: true }));
+
+      expect(mocks.onFocusOutside).not.toHaveBeenCalled();
+      expect(mocks.onInteractOutside).not.toHaveBeenCalled();
+      cleanup();
+    });
+
+    it("still triggers on pointerdown on a sibling in the same shadow root", () => {
+      const { mocks, outside, cleanup } = setupShadowTest();
+
+      outside.dispatchEvent(
+        new PointerEvent("pointerdown", { bubbles: true, composed: true, pointerType: "mouse" }),
+      );
+
+      expect(mocks.onPointerDownOutside).toHaveBeenCalledTimes(1);
+      expect(mocks.onInteractOutside).toHaveBeenCalledTimes(1);
+      cleanup();
+    });
+
+    it("passes the retargeted element, not the shadow host, to shouldExcludeElement", () => {
+      // The mechanism behind kobaltedev/kobalte#445: a consumer excludes its trigger via
+      // `shouldExcludeElement`, but was handed the shadow host, which never matches the trigger —
+      // so the layer dismissed on the very interaction that was meant to be exempt.
+      const seen: Element[] = [];
+      const { outside, cleanup } = setupShadowTest({
+        shouldExcludeElement: el => {
+          seen.push(el);
+          return false;
+        },
+      });
+
+      outside.dispatchEvent(
+        new PointerEvent("pointerdown", { bubbles: true, composed: true, pointerType: "mouse" }),
+      );
+
+      expect(seen).toContain(outside);
+      expect(seen.some(el => el.shadowRoot != null)).toBe(false);
+      cleanup();
+    });
+  });
 });