People leave jobs all the time. People get run over by busses or win the lottery. People forget stuff.
It’s important to document things, especially technical things.
code != documentation
Source code explains how things work… it’s simply telling the computer the algorithm you want run. What’s not often mentioned is wider context.
- Why do we want this thing at all?
- What problem does it solve?
- Why don’t we approach this in a different way?
- What are the current constraints? Is there time / business / financial pressure?
- Is this meant to be scalable or an MVP?
- What does this object / table represent?
Use comments and documentation widely to make it easier for the next person - often you.