Deep Linking

Covers the non-obvious parts of URL-driven state: which history method to use, how to avoid re-render loops, handling defaults without polluting the URL, and keeping multiple independent state slices in sync. Skips basic routing setup — assumes a router exists.

Discovery

Before writing anything, answer:

1. What state belongs in the URL? Filters, pagination, selected tab, open modal, sort order — or all of these?
2. Framework/router: React Router, Next.js (App Router or Pages), Vue Router, vanilla history API?
3. Shareable vs navigable: Should back-button step through filter changes, or only page navigations?
4. Default values: Should defaults appear in the URL (?page=1) or be omitted (cleaner, but requires careful hydration)?
5. Conflicts: Does any state also live in a store (Zustand, Redux)? URL must be the source of truth, not both.

Core Patterns