v0.19.0

Added

• Git 3.0 readiness: git-hunk works in SHA-256 and reftable repositories, the defaults Git 3.0 gives every new repository, as well as in SHA-1 ones, with nothing to configure. Wherever it needs an object ID it asks git, which answers in the repository's own format. The integration suite gains a git3-defaults hostile profile (SHA-256, reftable, main, safe.bareRepository=explicit) that CI runs on every push; it refuses a git too old to honour those settings rather than passing vacuously.

Fixed

• --ref <initial-commit> failed in a SHA-256 repository with "unknown revision". It diffed against the SHA-1 empty tree, which a SHA-256 repository does not have.
• An untracked symlink's diff named its blob with a SHA-1 hash even in a SHA-256 repository.
• An uppercase hunk-hash prefix passed validation and then matched nothing ("no hunk matching"). It is now rejected by name ("hunk hashes are lowercase hex"), in line with Git 3.0's lowercase-only object IDs.
• commit --amend dropped the original commit's changes. The temp index was seeded from HEAD~1 while the hunks are relative to HEAD, so the amended commit held only the new hunk and the original change reappeared as staged. On a root commit --amend failed outright. Both now build on HEAD, as git commit --amend does.
• commit --dry-run checked against the real index while the commit builds on HEAD, so a staged edit next to the target hunk made the preview pass and the commit fail.
• A file added by a pre-commit hook with a non-ASCII name was left behind as a staged deletion, which the next plain git commit would record. Path listings are now NUL-separated, and every file of a multi-file commit counts as a target (previously only the first file of each patch did).
• Binary renames: a.bin → b.bin was listed and reset under the old path, leaving the rename staged, and a rename between names of different lengths was invisible to list, count and -v. Renames now take their path from rename to. A C-quoted path ending in a backslash was dropped by the same parser.
• add/reset with a --file that matched no hunk exited 0 having done nothing. They now report "no hunks matching file" and exit 1, like the other commands.
• add, reset and restore --dry-run rejected every file↔symlink typechange ("already exists" / "wrong type") that the real operation applies cleanly. The dry run now checks the delete and create halves as one sequence.
• reset --ref <X> could not succeed: git received diff --cached X^..X and printed its usage text. It now takes hunks from the same diff as list --ref X and removes them from the index, the mirror of add --ref X.

Changed

• Internal restructure with no change in behaviour, checked against the previous binary across a few hundred scenarios:
  • The per-command option structs share one Common struct, replacing a field-copy layer driven by reflection. Whether a command accepts --3way now comes from the command spec.
  • Subcommands dispatch through one typed path.
  • Commands load and select hunks through one shared path.
  • Patches are built in the order they apply.
  • One numbered iterator walks every hunk body, so diff -n numbering and line-spec selection cannot drift apart.
  • diff.zig parses one file section at a time, shared with the skipped-path report.
  • Colour, hash and summary rendering live in format.zig.
  • Stash machinery moves into stash.zig, and new head_match.zig and check.zig hold the index→HEAD matcher and check's resolver.
• Test suites use the harness first_sha helper throughout, and the symlink and typechange cases move to tests/test_symlink.sh.