bench_downloader.py sweeps the unified downloader over synthetic
loopback segments (latency/rate shaping, fault injection, hedge and
sweep-safety checks) or real URLs, with --procs and --no-read1 A/B
flags. live_manifest_test.py drives the full DASH/HLS/ISM pipeline
against 11 public streams on 8 CDNs; bench-urls/ holds reproducible
real-CDN URL lists.
