Does the fixed context in attention mechanism is accquired after getting the decoder hidden layer of the first hidden state?

Question

here, the fixed context vector (ci) is used for the decoder model, why the decoder model also used by the attention weights. On the first (c1), does that mean the decoder does not have context ? (i = 1 ; c1 - 1 = c0). Thanks

references : Jurafsky, D., & Martin, J. H. (2023). Speech and language processing: An Introduction to Natural Language Processing(pp.205-208), (3rd ed. draft), Computational Linguistics, and Speech Recognition. Prentice Hall.