fix: handle initial: false for nested route after first initialization

packages/core/src/__tests__/index.test.tsx

@@ -1006,6 +1006,95 @@ it('navigates to nested child in a navigator with initial: false', () => {
     stale: false,
     type: 'test',
   });
+
+  const third = render(
+    <BaseNavigationContainer
+      ref={navigation}
+      initialState={{
+        index: 1,
+        routes: [
+          { name: 'foo' },
+          {
+            name: 'bar',
+            params: { initial: false, params: { test: 42 }, screen: 'bar-b' },
+            state: {
+              index: 1,
+              key: '7',
+              routes: [
+                {
+                  name: 'bar-a',
+                  params: { lol: 'why' },
+                },
+                {
+                  name: 'bar-b',
+                  params: { some: 'stuff' },
+                },
+              ],
+              type: 'test',
+            },
+          },
+        ],
+        type: 'test',
+      }}
+    >
+      <TestNavigator>
+        <Screen name="foo" component={TestComponent} />
+        <Screen name="bar">
+          {() => (
+            <TestNavigator initialRouteName="bar-a">
+              <Screen
+                name="bar-a"
+                component={TestComponent}
+                initialParams={{ lol: 'why' }}
+              />
+              <Screen
+                name="bar-b"
+                component={TestComponent}
+                initialParams={{ some: 'stuff' }}
+              />
+            </TestNavigator>
+          )}
+        </Screen>
+      </TestNavigator>
+    </BaseNavigationContainer>
+  );
+
+  expect(third).toMatchInlineSnapshot(`"[bar-b, {\\"some\\":\\"stuff\\"}]"`);
+
+  expect(navigation.current?.getRootState()).toEqual({
+    index: 1,
+    key: '11',
+    routeNames: ['foo', 'bar'],
+    routes: [
+      { key: 'foo-9', name: 'foo' },
+      {
+        key: 'bar-10',
+        name: 'bar',
+        params: { initial: false, params: { test: 42 }, screen: 'bar-b' },
+        state: {
+          index: 1,
+          key: '14',
+          routeNames: ['bar-a', 'bar-b'],
+          routes: [
+            {
+              key: 'bar-a-12',
+              name: 'bar-a',
+              params: { lol: 'why' },
+            },
+            {
+              key: 'bar-b-13',
+              name: 'bar-b',
+              params: { some: 'stuff' },
+            },
+          ],
+          stale: false,
+          type: 'test',
+        },
+      },
+    ],
+    stale: false,
+    type: 'test',
+  });
 });
 
 it('gives access to internal state', () => {

packages/core/src/useNavigationBuilder.tsx

@@ -177,9 +177,7 @@ export default function useNavigationBuilder<
     | NavigatorRoute
     | undefined;
 
-  const previousNestedParamsRef = React.useRef(
-    route?.params?.initial === false ? undefined : route?.params
-  );
+  const previousNestedParamsRef = React.useRef(route?.params);
 
   React.useEffect(() => {
     previousNestedParamsRef.current = route?.params;
@@ -189,7 +187,9 @@ export default function useNavigationBuilder<
   const { current: router } = React.useRef<Router<State, any>>(
     createRouter({
       ...((rest as unknown) as RouterOptions),
-      ...(route?.params && typeof route.params.screen === 'string'
+      ...(route?.params &&
+      route.params.initial !== false &&
+      typeof route.params.screen === 'string'
         ? { initialRouteName: route.params.screen }
         : null),
     })
@@ -269,6 +269,8 @@ export default function useNavigationBuilder<
   >();
   const initializedStateRef = React.useRef<State>();
 
+  let isFirstStateInitialization = false;
+
   if (
     initializedStateRef.current === undefined ||
     currentState !== previousStateRef.current
@@ -277,16 +279,21 @@ export default function useNavigationBuilder<
     // We also need to re-initialize it if the state passed from parent was changed (maybe due to reset)
     // Otherwise assume that the state was provided as initial state
     // So we need to rehydrate it to make it usable
-    initializedStateRef.current =
-      currentState === undefined || !isStateValid(currentState)
-        ? router.getInitialState({
-            routeNames,
-            routeParamList,
-          })
-        : router.getRehydratedState(currentState as PartialState<State>, {
-            routeNames,
-            routeParamList,
-          });
+    if (currentState === undefined || !isStateValid(currentState)) {
+      isFirstStateInitialization = true;
+      initializedStateRef.current = router.getInitialState({
+        routeNames,
+        routeParamList,
+      });
+    } else {
+      initializedStateRef.current = router.getRehydratedState(
+        currentState as PartialState<State>,
+        {
+          routeNames,
+          routeParamList,
+        }
+      );
+    }
   }
 
   React.useEffect(() => {
@@ -313,7 +320,8 @@ export default function useNavigationBuilder<
 
   if (
     typeof route?.params?.screen === 'string' &&
-    route.params !== previousNestedParamsRef.current
+    (route.params !== previousNestedParamsRef.current ||
+      (route.params.initial === false && isFirstStateInitialization))
   ) {
     // If the route was updated with new name and/or params, we should navigate there
     // The update should be limited to current navigator only, so we call the router manually