What was going wrong
[WHAT WAS BROKEN, SLOW, MISSING OR IMPOSSIBLE before this existed. Give the stakes — who was hurting and by how much. Two or three sentences.]
[ONE STRONG SENTENCE ON WHAT THIS IS AND WHY IT MATTERED — the version someone reads before deciding whether to keep going.]
[WHAT WAS BROKEN, SLOW, MISSING OR IMPOSSIBLE before this existed. Give the stakes — who was hurting and by how much. Two or three sentences.]
[THE ARCHITECTURE AND THE REASONING. Name the tradeoff you actually agonised over — this is the part engineers read, and the part that separates you from a list of tutorials.]
[THE OUTCOME, with a number if one exists. What you would do differently is a strong close — it reads as seniority, not weakness.]