Show HN: Twain, a diff viewer like Meld, but for the age of AI

Twain is a modern diff viewer that reimagines the Meld experience for teams that want a faster, tree-focused review workflow with AI-assisted commenting. It preserves familiar elements - clear side-by-side change visualization, scrolling minimaps, Git support and speed - while adding features Meld lacks: a single sequential view showing all files from a Git diff, a high-performance file tree, options to show full files or only changed hunks with granular reveal of unchanged context, Tree-sitter-based syntax highlighting, and a global search across modified files. Users can attach comments to lines or sets of changes and invoke AI agents from the CLI to read and extend those comments, enabling automated suggestions or augmentations during review. Twain is released under GPL-3.0 and distributed as binaries or a Flatpak; it can also be built from source (requires GTK 4, GtkSourceView 5 and libadwaita).

Usage is straightforward: run Twain in a project directory or against Git revisions, select lines and press C or right-click to add comments, and let integrated AI tooling augment review notes. It explicitly does not provide merge or three-way comparison features, multi-VCS support, or in-place file editing, so it targets reviewers who want a fast, read-and-comment experience rather than an editor/merge tool. Installation options include downloading releases or installing via cargo from the project’s Git URL.