When I want to make a meal that will provide enough leftovers to have lunch for the week taken care of, I usually pasta. Basically I make a warm pasta salad for dinner, then eat it cold for lunch over the next few days. To make it a complete meal, I usually toss in a generous amount of vegetables and either beans or nuts as some sort of protein.
Since I'm obsessed with chickpeas, they are my go-to legume. Unfortunately, sometimes I do not have any chickpeas, like the time I made this pasta dish:
Buuuut as it sat in the fridge over the next few days, the beans got this weird slimy texture. They weren't going bad or anything, they were just continuing to absorb moisture from the other ingredients, and getting increasingly mushy. The taste remained the same but by the second lunch of leftovers the texture was awwwwwwful, ugh.
So! a word to the wise: if you're making a bean-and-pasta dish that will result in leftovers, go for a firm-skinned bean like chickpeas, cannellini, or kidney beans. Because maaaaaan is it gross otherwise!