diff --git a/test/floating-attach.test.ts b/test/floating-attach.test.ts
new file mode 100644
index 0000000..0cf286c
--- /dev/null
+++ b/test/floating-attach.test.ts
@@ -0,0 +1,55 @@
+import { describe, expect, it } from "./suite.ts";
+import { createTerm } from "../term.ts";
+import { close, fixed, open, text } from "../ops.ts";
+
+// Clay attach-point enum (clay.h L433-441): LEFT_TOP=0 ... RIGHT_TOP=6.
+const ATTACH_TO_PARENT = 1;
+const LEFT_TOP = 0;
+const RIGHT_TOP = 6;
+
+describe("floating attach corners", () => {
+  it("anchors a float to the parent's right-top corner", async () => {
+    let term = await createTerm({ width: 10, height: 3 });
+    // PROPOSED attachPoints: {element, parent} so the float's element corner
+    // attaches to a chosen parent corner. Cast so it type-checks today; the
+    // parent corner is dropped at runtime against the current build.
+    let res = term.render([
+      open("box", { layout: { width: fixed(5), height: fixed(3) } }),
+      open("dot", {
+        floating: {
+          x: 0,
+          y: 0,
+          attachTo: ATTACH_TO_PARENT,
+          attachPoints: { element: LEFT_TOP, parent: RIGHT_TOP } as never,
+        },
+      }),
+      text("X"),
+      close(),
+      close(),
+    ]);
+    // pins: float's left edge sits at parent.x(0) + parent.width(5) = 5
+    expect(res.info.get("dot")!.bounds.x).toBe(5);
+  });
+
+  it("keeps the parent corner independent of the element corner", async () => {
+    let term = await createTerm({ width: 10, height: 3 });
+    // element RIGHT_TOP, parent RIGHT_TOP: the float's right edge attaches to
+    // the parent's right edge, so its left edge lands at parent.width - 1 = 4.
+    let res = term.render([
+      open("box", { layout: { width: fixed(5), height: fixed(3) } }),
+      open("dot", {
+        floating: {
+          x: 0,
+          y: 0,
+          attachTo: ATTACH_TO_PARENT,
+          attachPoints: { element: RIGHT_TOP, parent: RIGHT_TOP } as never,
+        },
+      }),
+      text("X"),
+      close(),
+      close(),
+    ]);
+    // pins: element RIGHT_TOP onto parent RIGHT_TOP -> dot.x = 5 - 1 = 4
+    expect(res.info.get("dot")!.bounds.x).toBe(4);
+  });
+});