🔧 Arc 11 Catch-Up: Composing Solana Programs with CPIs

Arc 11 covered Days 71–77 of Epoch 3, and it was all about Cross-Program Invocations.

In Arc 9, we wrote our first Solana program.

In Arc 10, we gave that program a more useful state model with Program Derived Addresses.

But our programs were still mostly working alone.

They could read and update their own accounts, enforce their own...