Transaction interface control

1. A merchant point-of-sale (POS) system used in performing POS transactions between a customer and a merchant, the point of sale system comprising:

a customer terminal configured to display a customer POS interface, the customer POS interface configured to receive input from the customer during a POS transaction with the merchant;

a merchant terminal configured to display a merchant POS interface, the merchant POS interface configured to receive input from the merchant during the POS transaction with the customer;

one or more processors; and

one or more non-transitory computer-readable media storing instructions executable by the one or more processors, wherein the instructions program the one or more processors to perform acts comprising:

receiving, at the customer terminal via the customer POS interface, a first input, the first input comprising customer data;

sending, from the customer terminal to the merchant terminal, an indication of the first input;

responsive to the indication of the first input, activating a locked mode of the merchant POS interface, wherein the locked mode substantially precludes data input by the merchant on the merchant POS interface;

receiving, at the customer terminal, an indication of completion of the first input;

sending, from the customer terminal to the merchant terminal, a message indicating completion of the first input; and

responsive to the message, de-activating the locked mode of the merchant POS interface.

2. The merchant POS system as claim 1 recites, prior to the receiving the indication of completion of the first input, the acts further comprising:

presenting, on the merchant POS interface, an override option configured to enable the merchant to de-activate the locked mode;

receiving, at the merchant terminal, a selection of the override option; and

responsive to receiving the selection of the override option, de-activating the locked mode of the merchant POS interface.

3. The merchant POS system as claim 1 recites, prior to the receiving the indication of completion of the first input, acts further comprising:

presenting, on the merchant POS interface, an option to select an alternate merchant POS interface;

receiving, at the merchant terminal, a selection of the alternate merchant POS interface;

presenting, on the merchant terminal, the alternate merchant POS interface;

receiving, at the merchant terminal, transaction data for a second transaction between the merchant and a second customer; and

processing the second transaction via the alternate merchant POS interface.

4. The merchant POS system as claim 1 recites, the operations further comprising:

presenting, on the merchant POS interface while operating in the locked mode, a representation of the first input by the customer.

5. The merchant POS system as claim 4 recites, the operations further comprising:

identifying sensitive information provided by the customer in the first input; and

redacting the sensitive information from the representation of the first input on the merchant POS interface.

6. A method implemented at least in part by a point-of-sale (POS) comprising a first display and a second display, the method comprising:

presenting a first user interface (UI) on the first display of the POS system;

presenting a second UI on the second display of the POS system;

receiving an input via the first UI; and

at least partly responsive to the input, activating a locked mode on the second UI.

7. The method as claim 6 recites, further comprising:

presenting, on the second UI, a control that, when selected, causes the POS system to override the locked mode on the second UI;

receiving a selection of the control; and

responsive to receiving the selection, de-activating the locked mode of the second UI.

8. The method as claim 7 recites, further comprising:

sending a deactivation message to the first UI; and

causing the first UI to activate a locked mode.

9. The method as claim 6 recites, further comprising:

receiving an indication that input on the first UI has been completed; and

at least partly responsive to the indication, de-activating the locked mode on the second UI.

10. The method as claim 6 recites, further comprising:

sending, from a first control module associated with the first UI to a second control module associated with the second UI, an indication of the input; and

automatically activating, by the second control module, the locked mode on the second UI.

11. The method as claim 6 recites, wherein the input comprises one or more of:

customer data;

transaction data; or

payment data.

12. The method as claim 6 recites, wherein the first display is a display associated with a customer-facing device and the second display is a display associated with a merchant-facing device, the customer-facing device and the merchant-facing device being configured to conduct a POS transaction between a customer and a merchant.

13. The method as claim 6 recites, wherein the first display comprises a customer terminal of a merchant device and the second display comprises a merchant terminal of the merchant device.

14. The method as claim 6 recites, the operations further comprising:

presenting, on the second UI, a representation of the input;

identifying sensitive information in the input; and

redacting at least a portion of the sensitive information from the representation of the input presented on the second user interface.

15. A computing device used as a merchant terminal in a point-of-sale (POS) system, the computing device comprising:

one or more processors;

one or more non-transitory computer-readable media storing instructions executable by the one or more processors, wherein the instructions program the one or more processors to perform acts comprising:

presenting a first user interface (UI) on a first display of the computing device;

presenting a second UI on a second display of the computing device;

receiving an input via the first UI; and

at least partly responsive to the input via the first UI, activating a locked mode on the second UI.

16. The computing device as claim 15 recites, the acts further comprising:

presenting, on the second UI, a control that, when selected, causes the POS system to override the locked mode on the second UI;

receiving, on the second UI, a selection of the control; and

responsive to the receiving the selection, de-activating the locked mode of the second UI.

17. The computing device as claim 16 recites, the acts further comprising:

sending a de-activation message to the first UI, the de-activation message comprising an indication that the locked mode of the second UI has been de-activated; and

causing the first UI to activate a locked mode.

18. The computing device as claim 15 recites, the acts further comprising:

receiving an indication that input on the first UI has been completed; and

at least partly responsive to the indication, de-activating the locked mode on the second UI.

19. The computing device as claim 15 recites, wherein the second UI is a merchant-facing UI, the acts further comprising:

receiving, via the merchant terminal while operating in a locked mode, a selection of an alternate merchant UI;

presenting, on the second display, the alternate merchant UI;

receiving, at the merchant terminal, transaction data for a second transaction; and

processing input associated with the second transaction via the alternate merchant UI.

20. The computing as claim 15 recites, the acts further comprising:

presenting, on the second UI while operating in the locked mode, a representation of the input;

identifying sensitive information in the input; and

redacting the sensitive information from the representation of the input on the second UI.