lamp/.agents/skills/building-native-ui/references/route-structure.md

Route Structure

File Conventions

• Routes belong in the app directory
• Use [] for dynamic routes, e.g. [id].tsx
• Routes can never be named (foo).tsx - use (foo)/index.tsx instead
• Use (group) routes to simplify the public URL structure
• NEVER co-locate components, types, or utilities in the app directory - these should be in separate directories like components/, utils/, etc.
• The app directory should only contain route and _layout files; every file should export a default component
• Ensure the app always has a route that matches "/" so the app is never blank
• ALWAYS use _layout.tsx files to define stacks

Dynamic Routes

Use square brackets for dynamic segments:

app/
  users/
    [id].tsx        # Matches /users/123, /users/abc
    [id]/
      posts.tsx     # Matches /users/123/posts

Catch-All Routes

Use [...slug] for catch-all routes:

app/
  docs/
    [...slug].tsx   # Matches /docs/a, /docs/a/b, /docs/a/b/c

Query Parameters

Access query parameters with the useLocalSearchParams hook:

import { useLocalSearchParams } from "expo-router";

function Page() {
  const { id } = useLocalSearchParams<{ id: string }>();
}

For dynamic routes, the parameter name matches the file name:

• [id].tsx → useLocalSearchParams<{ id: string }>()
• [slug].tsx → useLocalSearchParams<{ slug: string }>()

Pathname

Access the current pathname with the usePathname hook:

import { usePathname } from "expo-router";

function Component() {
  const pathname = usePathname(); // e.g. "/users/123"
}

Group Routes

Use parentheses for groups that don't affect the URL:

app/
  (auth)/
    login.tsx       # URL: /login
    register.tsx    # URL: /register
  (main)/
    index.tsx       # URL: /
    settings.tsx    # URL: /settings

Groups are useful for:

• Organizing related routes
• Applying different layouts to route groups
• Keeping URLs clean

Stacks and Tabs Structure

When an app has tabs, the header and title should be set in a Stack that is nested INSIDE each tab. This allows tabs to have their own headers and distinct histories. The root layout should often not have a header.

• Set the 'headerShown' option to false on the tab layout
• Use (group) routes to simplify the public URL structure
• You may need to delete or refactor existing routes to fit this structure

Example structure:

app/
  _layout.tsx — <Tabs />
  (home)/
    _layout.tsx — <Stack />
    index.tsx — <ScrollView />
  (settings)/
    _layout.tsx — <Stack />
    index.tsx — <ScrollView />
  (home,settings)/
    info.tsx — <ScrollView /> (shared across tabs)

Array Routes for Multiple Stacks

Use array routes '(index,settings)' to create multiple stacks. This is useful for tabs that need to share screens across stacks.

app/
  _layout.tsx — <Tabs />
  (index,settings)/
    _layout.tsx — <Stack />
    index.tsx — <ScrollView />
    settings.tsx — <ScrollView />

This requires a specialized layout with explicit anchor routes:

// app/(index,settings)/_layout.tsx
import { useMemo } from "react";
import Stack from "expo-router/stack";

export const unstable_settings = {
  index: { anchor: "index" },
  settings: { anchor: "settings" },
};

export default function Layout({ segment }: { segment: string }) {
  const screen = segment.match(/\((.*)\)/)?.[1]!;

  const options = useMemo(() => {
    switch (screen) {
      case "index":
        return { headerRight: () => <></> };
      default:
        return {};
    }
  }, [screen]);

  return (
    <Stack>
      <Stack.Screen name={screen} options={options} />
    </Stack>
  );
}

Complete App Structure Example

app/
  _layout.tsx — <NativeTabs />
  (index,search)/
    _layout.tsx — <Stack />
    index.tsx — Main list
    search.tsx — Search view
    i/[id].tsx — Detail page
components/
  theme.tsx
  list.tsx
utils/
  storage.ts
  use-search.ts

Layout Files

Every directory can have a _layout.tsx file that wraps all routes in that directory:

// app/_layout.tsx
import { Stack } from "expo-router/stack";

export default function RootLayout() {
  return <Stack />;
}

// app/(tabs)/_layout.tsx
import { NativeTabs, Icon, Label } from "expo-router/unstable-native-tabs";

export default function TabLayout() {
  return (
    <NativeTabs>
      <NativeTabs.Trigger name="index">
        <Label>Home</Label>
        <Icon sf="house.fill" />
      </NativeTabs.Trigger>
    </NativeTabs>
  );
}

Route Settings

Export unstable_settings to configure route behavior:

export const unstable_settings = {
  anchor: "index",
};

• initialRouteName was renamed to anchor in v4

Not Found Routes

Create a +not-found.tsx file to handle unmatched routes:

// app/+not-found.tsx
import { Link } from "expo-router";
import { View, Text } from "react-native";

export default function NotFound() {
  return (
    <View>
      <Text>Page not found</Text>
      <Link href="/">Go home</Link>
    </View>
  );
}