The fixed three-message tool window collapsed long transcripts to a handful of messages: a 405-message run kept two of 202 tool calls, and the model re-ran what it could no longer see. Pruning now drops reasoning first and keeps the widest recent tool tail that fits a ladder, the SDK carries that view into later steps, and the turn emits one compaction event instead of one per step.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>