Exchange-rate movement is not an App Store price drop

A cross-country comparison combines a storefront observation and an exchange-rate observation. The storefront fact is the local amount in its currency. The exchange rate translates that amount into a common reference currency for ranking.

These observations can have different timestamps and change independently. A useful interface shows both roles rather than presenting the converted estimate as if Apple published it.

Suppose a plan costs JPY 3,000 in Japan on Monday and JPY 2,500 on Tuesday. If both observations refer to the same product and billing period, that is a local-price decrease. The event can be measured within JPY without using any exchange rate.

The reverse is also true: a move from JPY 3,000 to JPY 3,500 is a local increase, even if currency movement happens to keep the converted USD estimate similar.

Now suppose the price stays JPY 3,000 but the yen weakens against the dollar. The converted estimate may fall and Japan may move upward in the cheapest-country ranking. That can be useful comparison information, but it is not a sale and should not create a price-drop event.

App Price Atlas describes this as a currency-driven ranking change or FX opportunity only when the movement is material and stable enough to be useful.

• Local amount changed: possible App price event.
• Only converted amount changed: currency effect.
• Both changed: explain each component separately.

Calling currency movement a developer discount produces false alerts, inaccurate price history and misleading search snippets. It can also encourage users to act on a ranking that reverses with the next daily rate.

Keeping immutable local observations and dated exchange rates makes the comparison reproducible. Readers can see whether the App changed its price or the common measuring stick moved.