Persist the Useful User Data

The live converter works, but the project still needs to remember the pairs and conversions that matter to the user. This module completes the local data layer with localStorage.

What you will build

• Favorites toggling for the active pair
• Favorite cards that can reopen a pair
• conversion history with a 30-item limit
• empty states, remove actions, and counters

Checkpoint

Save a pair, refresh the page, reopen it from Favorites, perform a conversion, and find it in History.

Next, we will finish the visual data story with historical rates and the Canvas chart.