generate a coupon automatically after checkout
Here is a little help.

Actions


Add Action - Entites - Create a new entity - select Commercce Coupon - Continue - Save
Add Action - Data - Set a data value - select the field you want (ex. entity-ecreated:commerce-coupon-number-of-uses) - enter the value you want - Save
Do the 2. for the fields you want


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At the end I decided to do my custom Rule action for creating a coupon, because is more flexible.