diff --git a/packages/@ember/-internals/glimmer/tests/integration/shrink-test.js b/packages/@ember/-internals/glimmer/tests/integration/shrink-test.js
new file mode 100644
index 00000000000..656b17eaa0a
--- /dev/null
+++ b/packages/@ember/-internals/glimmer/tests/integration/shrink-test.js
@@ -0,0 +1,77 @@
+import { RenderingTestCase, moduleFor, strip } from 'internal-test-helpers';
+
+// Byte-identical on both branches. Does a plain (non-tracked) array that shrinks
+// *during* render stop the iteration, or produce phantom items?
+moduleFor(
+  'each over an array that shrinks mid-render',
+  class extends RenderingTestCase {
+    // Mutation from inside the block body. VM_ITERATE_OP renders each item's
+    // block before calling next() again, so body code runs mid-iteration.
+    ['@test body getter truncates the array']() {
+      let items = [];
+      let log = [];
+      for (let i = 0; i < 4; i++) {
+        items.push({
+          id: i,
+          get name() {
+            log.push(i);
+            if (i === 0) items.length = 1; // drop items 1..3
+            return `item-${i}`;
+          },
+        });
+      }
+
+      this.render(`{{#each this.items as |item|}}<b>{{item.name}}</b>{{/each}}`, { items });
+
+      let rendered = this.element.querySelectorAll('b').length;
+      // eslint-disable-next-line no-console
+      console.log(`__SHRINK__ ${JSON.stringify({ case: 'body', blocks: rendered, reads: log })}`);
+      this.assert.ok(true, `rendered ${rendered} blocks`);
+    }
+
+    // Mutation from keyFor, which runs inside next() itself.
+    ['@test key getter truncates the array']() {
+      let items = [];
+      let log = [];
+      for (let i = 0; i < 4; i++) {
+        items.push({
+          id: i,
+          get k() {
+            log.push(i);
+            if (i === 0) items.length = 1;
+            return `k-${i}`;
+          },
+        });
+      }
+
+      this.render(`{{#each this.items key="k" as |item|}}<b>{{item.id}}</b>{{/each}}`, { items });
+
+      let rendered = this.element.querySelectorAll('b').length;
+      // eslint-disable-next-line no-console
+      console.log(`__SHRINK__ ${JSON.stringify({ case: 'key', blocks: rendered, reads: log })}`);
+      this.assert.ok(true, `rendered ${rendered} blocks`);
+    }
+
+    // A hole: length is UNCHANGED, but the slot is empty. A length-based bound
+    // cannot see this -- does either branch stop, or render undefined?
+    ['@test body getter deletes a later element, leaving a hole']() {
+      let items = [];
+      for (let i = 0; i < 4; i++) {
+        items.push({
+          id: i,
+          get name() {
+            if (i === 0) delete items[2];
+            return `item-${i}`;
+          },
+        });
+      }
+
+      this.render(`{{#each this.items as |item|}}<b>{{item.id}}</b>{{/each}}`, { items });
+
+      let rendered = this.element.querySelectorAll('b').length;
+      // eslint-disable-next-line no-console
+      console.log(`__SHRINK__ ${JSON.stringify({ case: 'hole', blocks: rendered, len: items.length })}`);
+      this.assert.ok(true, `rendered ${rendered} blocks`);
+    }
+  }
+);
diff --git a/testem.shrink.cjs b/testem.shrink.cjs
new file mode 100644
index 00000000000..794fd9c4f77
--- /dev/null
+++ b/testem.shrink.cjs
@@ -0,0 +1,6 @@
+module.exports = {
+  test_page: 'index.html/?filter=each%20over%20an%20array%20that%20shrinks%20mid-render',
+  cwd: 'dist', timeout: 540, parallel: 1, disable_watching: true,
+  launch_in_ci: ['Chrome'], browser_start_timeout: 120, browser_disconnect_timeout: 1200,
+  browser_args: { Chrome: { ci: ['--headless','--disable-dev-shm-usage','--mute-audio','--remote-debugging-port=0'] } },
+};