| name | expo-router |
| description | Expo Router rules for Modelence mobile apps — URL and group segment semantics, the canonical tabs layout, and the pre-completion checklist. Use before creating, moving, renaming, or linking any screen under mobile/app/. |
Expo Router rules (Modelence mobile)
Violations of these rules cause "Unmatched Route" errors that type-checking cannot catch.
URL rules
(name) folder segments are groups — they are stripped from the URL. app/(tabs)/portfolio.tsx is reachable at /portfolio, never /(tabs)/portfolio or /tabs/portfolio.index.tsx inside any folder represents that folder's own URL. app/(tabs)/index.tsx resolves to /.- Exactly one file may resolve to
/. If you add (group)/index.tsx as the default screen, you MUST delete app/index.tsx. Two files resolving to the same route is undefined behavior.
- Never redirect to a screen's basename. Derive
href from the file path with groups stripped: app/(tabs)/markets.tsx → href="/markets", app/(tabs)/index.tsx → href="/".
Canonical tabs-without-auth structure
When the app does not require auth gating, the correct file layout is:
mobile/app/
├── _layout.tsx # Slot + providers — NO index.tsx at this level
└── (tabs)/
├── _layout.tsx # <Tabs />
├── index.tsx # default tab, URL = "/"
└── <screen>.tsx # other tabs, URL = "/<screen>"
Do NOT create app/index.tsx alongside (tabs)/index.tsx. The (tabs)/index.tsx already owns /.
Pre-completion checklist for mobile changes
Before reporting mobile work as done, verify ALL of the following:
- Every
<Redirect href="..."> and router.push("...") literal maps to a real file under mobile/app/ with groups stripped.
- Exactly one file resolves to
/ across all of app/ and its group subdirectories.
- Run
npx tsc --noEmit inside mobile/ and fix all errors.
- TypeScript passing says nothing about Expo Router's route graph — state explicitly that runtime verification requires opening the app in the mobile preview.
