A small tool for big diffs

Most of the trouble I see in production comes from boundary cases someone promised would never happen. The code is fine. The plan is fine. The promise is what ages badly.

Every time I revisit a project after six months, I find at least one place where past-me wrote a comment that present-me has now stopped trusting. Comments rot faster than code.

I keep a small log of decisions in a text file. Not architectural — just small ones. "Picked X over Y because Z." Future me reads it more than I thought he would.

Caches solve a problem and create three new ones: invalidation, observability, and the slow drift between what the cache thinks is true and what the source thinks is true.

When a system surprises me, my first instinct used to be to fix the surprise. Now my first instinct is to figure out which mental model of mine was wrong, and update that.

The team I learned the most from didn't have great tools. They had a great habit of reading each other's pull requests in full, including the parts that weren't theirs.