Hello everyone, I have a basic question. Suppose $A$, $B$, and $C$ are objects in a stable $\infty$-category together with maps $f : A \to B$ and $g : A \to C$. Is there a simple expression for the cofiber of the map $(f, g) : A \to B \oplus C$?

Preferably something in terms of the cofibers of $f$ and $g$.

the case where A,B, and C are all some fixed object X, and f and g are the identity map suggests that an expression of the kind you are looking for should not exist, since in this case cofib(f) = cofib(g) = 0, but cofib(f \oplus g) will usually be interesting. at least if 2 is invertible, the cofiber will simply be another copy of X, which seems hard to get from a pair of zeros.