bvandeusen
402086c34c
Owning the media fetch means a mid-download transport cut no longer refetches from zero. _fetch_to_file now resumes: on a transient retry, if bytes already landed in the .part, it requests Range: bytes=<have>- and appends on a 206; falls back to a clean truncate-and-restart if the server ignores Range (200) or the range is past EOF (416). The .part staging means a non-range server never corrupts the output — worst case is the old behavior (refetch from zero). Tests: mid-stream cut resumes from the offset (asserts the Range header); a Range-ignoring server refetches clean (no double-write). Test session fakes updated to accept the new headers kwarg. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>