2 / 9 Requirements & Scoping

Not A Feature

A product owner reviews the courier tracking design and adds one line to the brief:

The map should never show a courier at a spot they have already left.

The team files it with the mobile client as a rendering detail. What does that sentence actually constrain?

A

Whether the client may reuse a response. Cache-Control: no-store on the position endpoint stops the app redrawing a position it fetched earlier.

B

The age of the position by the time it is drawn, so it binds the phone's reporting interval and the push out of the server as much as it binds the client. It is unusable until someone replaces never with a threshold.

C

How the marker moves. Interpolating between the last two reported fixes keeps it travelling, so it is never drawn sitting on a point the courier has left.

D

Which copy the server reads. Serving the position from the primary instead of a read replica closes the window where a lookup misses the newest write.