fix: make nightdrive signage reliable and legible

tests/unit/navigation-controller.test.ts

@@ -206,6 +206,7 @@ describe("navigation epochs and effects", () => {
       epoch: 2,
       source: "passive-scroll",
       destinationId: null,
+      signDestinationId: null,
     });
   });
 
@@ -283,6 +284,23 @@ describe("navigation epochs and effects", () => {
       epoch: 2,
       source: "history-restoration",
       destinationId: "profile",
+      signDestinationId: null,
+    });
+  });
+
+  it("marks only an explicitly requested navigator epoch for roadside signage", () => {
+    const harness = createRuntime(true);
+    const controller = createNavigationController(sectionIds, harness.runtime);
+
+    controller.navigate("profile", target("profile"));
+    expect(controller.state().signDestinationId).toBeNull();
+
+    controller.navigate("experience", target("experience"), { requestSign: true });
+    expect(controller.state()).toMatchObject({
+      epoch: 2,
+      source: "explicit-navigation",
+      destinationId: "experience",
+      signDestinationId: "experience",
     });
   });