ASTARLab-s Explain the given change for the person who has to own it:
- What — the behavior before and after, in plain language, citing the specific files and functions.
- Why this approach — the alternative that was NOT taken and the reason.
- What could break — the assumptions, edge cases, and blast radius.
- Self-test — one concrete question whose answer proves the reader understood (e.g. "what happens if X is empty?"), with the answer below a spoiler line.
Keep it under 20 lines. The reader's understanding is the deliverable — if a part cannot be explained simply, flag that part as the risk.