diff --git a/packages/polyfill/e2e/polyfill-entry.ts b/packages/polyfill/e2e/polyfill-entry.ts
index 07dc5a8..af4e222 100644
--- a/packages/polyfill/e2e/polyfill-entry.ts
+++ b/packages/polyfill/e2e/polyfill-entry.ts
@@ -1088,9 +1088,11 @@ const identity = new IdentityStore(
     // `data` - the member its own example destructures first, and one of the three that
     // used to come back unfiltered.
     const read = (): string[] =>
-      [...(libUseShape(wsShape("urn:e2e:caps:Item"), EVERYTHING).data as Iterable<any>)].map(
-        (i) => i.v,
-      );
+      [
+        ...(libUseShape(wsShape("urn:e2e:caps:Item"), EVERYTHING).data as Iterable<
+          { v: string }
+        >),
+      ].map((i) => i.v);
     setCurrentUser("owner-O");
     getCaps().open("did:ng:o:protdoc", "protected");
     const link = getCaps().open("did:ng:o:pubdoc", "public");
diff --git a/packages/polyfill/src/emulated-verifier/read-filter.ts b/packages/polyfill/src/emulated-verifier/read-filter.ts
index 0b1875b..8155007 100644
--- a/packages/polyfill/src/emulated-verifier/read-filter.ts
+++ b/packages/polyfill/src/emulated-verifier/read-filter.ts
@@ -213,6 +213,12 @@ export function makeReadFilteredView<S extends object>(set: S, caps: CapRegistry
    * `DeepSignal<ReadOnlyArray>` instead of a `DeepSignalSet`, and an array is addressed by
    * INDEX and counts itself with `length`. Decided from the target once, so the view never
    * grows a member the collection it wraps does not have.
+   *
+   * MEASURED against the real `@ng-org/alien-deepsignals` rather than assumed, because the
+   * collection is itself a proxy and what it answers for a key it does not carry is its
+   * business: `deepSignal(new Set(...)).length` is `undefined` and its `Object.keys` is
+   * empty, while `deepSignal([...]).length` is a number. So the set form never enters this
+   * branch, and the set form is also the one with no key naming an item to project.
    */
   const arrayLike = typeof (set as { length?: unknown }).length === "number";
   /** The index a key names, or `null` when it names no position in this collection. */
diff --git a/packages/polyfill/test/read-filter.test.ts b/packages/polyfill/test/read-filter.test.ts
index 7d11704..e936db6 100644
--- a/packages/polyfill/test/read-filter.test.ts
+++ b/packages/polyfill/test/read-filter.test.ts
@@ -149,10 +149,10 @@ test("forEach is filtered too", () => {
 // hatch included, which `get` refuses by name. Everything built on that call goes the same
 // way: `Object.keys`, `Object.entries`, a spread, `JSON.stringify`, a console inspection.
 test("a descriptor cannot answer what reading the member refuses", () => {
-  const set = new Set<Item>([MINE]) as any;
+  const set: Set<Item> & { __raw__?: unknown } = new Set<Item>([MINE]);
   set.__raw__ = set;
   const { caps, become } = setup("alice");
-  const view = makeReadFilteredView(set, caps) as any;
+  const view = makeReadFilteredView(set, caps);
   become("bob");
   expect(() => Object.getOwnPropertyDescriptor(view, "__raw__")).toThrow(/raw collection/i);
 });
@@ -163,9 +163,9 @@ test("a descriptor cannot answer what reading the member refuses", () => {
 // count of what a holder may NOT read came back out through the other three, and the
 // descriptor handed back the items themselves.
 test("the array form counts and addresses the readable items, by every route", () => {
-  const items = [MINE, FOREIGN, LINKED];
+  const items: Item[] = [MINE, FOREIGN, LINKED];
   const { caps, become } = setup("alice");
-  const view = makeReadFilteredView(items, caps) as any;
+  const view = makeReadFilteredView(items, caps);
   become("bob"); // holds nothing of the three documents
 
   expect(view.length).toBe(0);
@@ -178,9 +178,9 @@ test("the array form counts and addresses the readable items, by every route", (
   become("alice"); // holds her own document and the one she published
   expect(view.length).toBe(2);
   expect(Object.keys(view)).toEqual(["0", "1"]);
-  expect(view[0].id).toBe("a");
-  expect(view[1].id).toBe("p");
-  expect(Object.getOwnPropertyDescriptor(view, "1")?.value.id).toBe("p");
+  expect(view[0]).toBe(MINE);
+  expect(view[1]).toBe(LINKED);
+  expect(Object.getOwnPropertyDescriptor(view, "1")?.value).toBe(LINKED);
   expect(2 in view).toBe(false);
   // `length` is the array's own key and is never hidden - a proxy may not drop a key the
   // target cannot configure away - but it is not a position and does not enumerate.