diff --git a/launcher/electron/runtime.cjs b/launcher/electron/runtime.cjs
index 854b5eba1..4c5d19706 100644
--- a/launcher/electron/runtime.cjs
+++ b/launcher/electron/runtime.cjs
@@ -697,6 +697,7 @@ class RuntimeHost {
       mode === "full" ? "--full" : "--browser-only",
       "--browser-host-descriptor",
       this.browserDescriptorPath,
+      "--replace-codex-route",
       "--acknowledge-unofficial",
       "--restart-service",
     ];
diff --git a/launcher/tests/runtime-host.test.cjs b/launcher/tests/runtime-host.test.cjs
index e17625e40..c17772b3e 100644
--- a/launcher/tests/runtime-host.test.cjs
+++ b/launcher/tests/runtime-host.test.cjs
@@ -31,14 +31,30 @@ test("core setup preserves an existing full-harness installation", async () => {
   const fixture = hostFor({ mode: "full" });
   const result = await fixture.host.setupCore();
   assert.equal(result.mode, "full");
-  assert.deepEqual(fixture.invocation().args.slice(0, 2), ["setup", "--full"]);
+  assert.deepEqual(fixture.invocation().args, [
+    "setup",
+    "--full",
+    "--browser-host-descriptor",
+    "/runtime/launcher-browser.json",
+    "--replace-codex-route",
+    "--acknowledge-unofficial",
+    "--restart-service",
+  ]);
 });
 
 test("core setup starts in browser-only mode when no installation exists", async () => {
   const fixture = hostFor(null);
   const result = await fixture.host.setupCore();
   assert.equal(result.mode, "browser-only");
-  assert.deepEqual(fixture.invocation().args.slice(0, 2), ["setup", "--browser-only"]);
+  assert.deepEqual(fixture.invocation().args, [
+    "setup",
+    "--browser-only",
+    "--browser-host-descriptor",
+    "/runtime/launcher-browser.json",
+    "--replace-codex-route",
+    "--acknowledge-unofficial",
+    "--restart-service",
+  ]);
 });
 
 test("launcher update transaction upgrades its owned full runtime with saved configuration", async () => {