Run the Full FX_CHECKER Test Pass

This is the final implementation lesson. Test the actual application end-to-end rather than testing isolated snippets.

Test the main workflows

1. Open Convert and enter a different amount.
2. Change the Send and Receive currencies.
3. Swap the pair.
4. Click Convert and verify a History entry appears.
5. Add and remove a Favorite.
6. Reopen a saved pair from Favorites.
7. Search the Rates table.
8. Use a Rates-table Convert action.
9. Switch chart ranges and wait for historical data.
10. Refresh the page and confirm Favorites/History are still present.

Test the fallback path

Temporarily break the live endpoint and confirm the fallback rate path still renders the converter and shows the unavailable-service status.

Test responsive behavior

Check the project at a desktop width and at a narrow phone width. The prepared CSS should move the sidebar navigation to the mobile navigation and stack the converter controls without horizontal overflow.

Checkpoint

The finished project starts, major workflows work end-to-end, stored data survives refreshes, API failure does not make the converter unusable, and the interface remains usable on narrow screens.