- Widen observer checkpoint test bounds from 4σ to 5σ — random calibration data can exceed 4.0 with 100 batches of normal(0,1) - Override SCCACHE_BUCKET="" in .rust-base so check/test jobs use PVC-backed SCCACHE_DIR instead of S3 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>