the .md scratch pad point is underrated, and the format matters more than people realize.

summaries ("tried X, tried Y, settled on Z") are better than nothing, but the next iteration can mostly reconstruct them from test results anyway. what's actually irreplaceable is the constraint log: "approach B rejected because latency spikes above N ms on target hardware" means the agent doesn't re-propose B the next session. without it, every iteration rediscovers the same dead ends.

ended up splitting it into decisions.md and rejections.md. counter-intuitively, rejections.md turned out to be the more useful file. the decisions are visible in the code. the rejections are invisible — and invisible constraints are exactly what agents repeatedly violate.