There are no preset roles in the Octopus development team, and we won’t tell you what to do each day. There is an iteration plan, and you are free to choose the assignment that suits you. If one day you would like to do back-end, you are free to accept a back-end task from the back log. The next day, you want to work on GUI? Go ahead.
Every day, you stay connected with the team through stand-up meetings. Every day, you validate code and ideas with your peers through design review, code review, and pair programming.
The main role of your team leader is to point developers in the right direction so they can achieve the objectives of the iteration, and ensure long-term architecture quality.