The URL is the Source of Truth

In modern SPAs, we often over-engineer state management stores (Redux, Zustand) for data that belongs in the URL. If a user filters a dashboard by "Status: Active" and refreshes the page, that filter should persist. If they send the link to a colleague, the colleague should see the same filtered view.

If the state is not in the URL, it is ephemeral. My rule of thumb: If it changes the data payload, it belongs in the query string. Client-side stores should be reserved for truly transient UI states (like whether a modal is open or a menu is expanded), not for data definition. Nine years on high-traffic news pages gave me the distributed-systems framing for why this keeps being right: URL-as-truth is single-leader replication — one authoritative writer, every view a follower. A constellation of client stores each holding its own copy of the filter is multi-leader replication, and you inherit its signature failure mode: divergence with no conflict-resolution story.