Every oldest(), stats() and put() globbed and sorted the whole spool directory, so draining a backlog cost O(N^2 log N). After an outage on a Pi 3B+ the writer thread sat at 100% CPU for minutes working through 3,300 batches. The directory is now scanned once at startup and the names, sizes and total are tracked as batches are added and removed; draining 3,300 batches drops from 59s to 0.24s on a laptop. Bump to 0.1.6. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>