uv 0.12.0 makes every `uv init` project a packaged build, and rejects .tar.bz2 sdists.

Astral shipped it July 28. New projects declare a build system and are packaged by default via uv_build, source moves under src/, console scripts get generated, and pyproject.toml gains an authors list. Source distributions must be .tar.gz per PEP 625. Wheel compression is limited to stored, DEFLATE, or zstd. Pre-release resolution defaults to if-necessary, matching pip. Security hardening blocks wheels that would overwrite a Python interpreter including case variants like Python.exe, rejects MD5-only hashes under --require-hashes, and makes an empty or invalid SSL_CERT_FILE/SSL_CERT_DIR fail HTTPS rather than silently falling back. Check your templates before upgrading.