diff --git a/packages/csr/src/reactive-runtime.ts b/packages/csr/src/reactive-runtime.ts
index 331556c3..8fffecae 100644
--- a/packages/csr/src/reactive-runtime.ts
+++ b/packages/csr/src/reactive-runtime.ts
@@ -1993,7 +1993,17 @@ export const REACTIVE_RUNTIME = String.raw`
       var eachDefinition = block.hasAttribute("data-wrn-each")
         ? decodeControlDefinition(block.getAttribute("data-wrn-each"))
         : null;
-      var firstRun = true;
+      /*
+       * Skip the first reactive pass only when hydrating server DOM.
+       *
+       * A block that arrived with the server HTML is already rendered, so
+       * redrawing on the first pass would discard it. A block created later by
+       * an outer block's rerender has no server DOM — outerLocals is how it
+       * receives its enclosing loop's scope, and is only ever set on that path.
+       * Skipping its first pass leaves it permanently empty, because its
+       * dependencies never change again to trigger a second one.
+       */
+      var firstRun = !outerLocals;
 
       function controlRead(name) {
         return Object.prototype.hasOwnProperty.call(inherited, name) ? inherited[name] : readScope(name);
@@ -2029,12 +2039,22 @@ export const REACTIVE_RUNTIME = String.raw`
           if (node.matches && node.matches("[data-wrn-if],[data-wrn-each]")) controls.push(node);
           if (node.querySelectorAll) Array.prototype.push.apply(controls, node.querySelectorAll("[data-wrn-if],[data-wrn-each]"));
           controls.forEach(function (nested) {
-            if (!nested.__wrnexusControl) setupControlBlock(nested, locals || inherited);
+            if (nested.__wrnexusControl) return;
+            /*
+             * Run the new block now rather than waiting for a sweep.
+             *
+             * reactive() only registers an effect; effects execute when
+             * renderAll sweeps the list. A state change runs just the affected
+             * effects, so a block registered during that rerender is queued and
+             * never invoked -- it would stay empty for the life of the page.
+             */
+            var runNested = setupControlBlock(nested, locals || inherited);
+            if (runNested) runNested();
           });
         });
       }
 
-      reactive(function () {
+      return reactive(function () {
         if (ifDefinition) {
           var selected = null;
           for (var branchIndex = 0; branchIndex < ifDefinition.length; branchIndex++) {
diff --git a/packages/csr/test/reactive.test.ts b/packages/csr/test/reactive.test.ts
index 8532ee0d..ca126b60 100644
--- a/packages/csr/test/reactive.test.ts
+++ b/packages/csr/test/reactive.test.ts
@@ -1631,3 +1631,47 @@ test("splitter announces its new size for the component to re-emit", () => {
   );
   expect(seen).toEqual([60]);
 });
+
+test("control blocks created by a client rerender render their own content", () => {
+  // A nested block that arrives with the server HTML is hydrated: its first
+  // reactive pass must NOT redraw, or it would throw away server DOM. A nested
+  // block created later by an outer rerender has no server DOM, so skipping its
+  // first pass leaves it permanently empty — its dependencies never change
+  // again to trigger a second one.
+  const inner = Buffer.from(
+    JSON.stringify([
+      { cond: "g.rows.length > 0", body: '<p class="has-rows">HAS</p>' },
+      { cond: null, body: '<p class="no-rows">NONE</p>' },
+    ]),
+  ).toString("base64");
+  const outer = Buffer.from(
+    JSON.stringify({
+      list: "groups",
+      item: "g",
+      body:
+        `<section class="group"><span data-text="g.name">{g.name}</span>` +
+        `<template data-wrn-if="${inner}"></template><template data-wrn-control-end></template>` +
+        `</section>`,
+      empty: "",
+    }),
+  ).toString("base64");
+
+  const win = mount(
+    `<div data-scope="groups: [{ name: 'g1', rows: ['a'] }]">` +
+      `<button data-on-click="groups = [{ name: 'g2', rows: [] }]">swap</button>` +
+      `<template data-wrn-each="${outer}"></template>` +
+      `<section class="group"><span data-text="g.name">g1</span>` +
+      `<template data-wrn-if="${inner}"></template><p class="has-rows">HAS</p>` +
+      `<template data-wrn-control-end></template></section>` +
+      `<template data-wrn-control-end></template>` +
+      `</div>`,
+  );
+
+  win.document.querySelector("button")!.click();
+
+  // The outer each rerendered: the new group's heading is present.
+  expect(win.document.querySelector(".group span")?.textContent).toBe("g2");
+  // The nested if inside that new row must have rendered its else branch.
+  expect(win.document.querySelector(".no-rows")?.textContent).toBe("NONE");
+  expect(win.document.querySelector(".has-rows")).toBeNull();
+});