snapper-fmt

snapper-fmt is a command-line tool designed to reformat academic and collaborative writing with semantic line breaks, placing each sentence on its own line. This approach makes changes in version control systems clearer by ensuring that only the edited sentences appear in diffs, rather than entire paragraphs, which reduces noise and improves collaboration among multiple authors.

The tool supports format-aware parsing for Org-mode, LaTeX, Markdown, reStructuredText (RST), and plaintext documents. It preserves structural elements such as math, tables, directives, drawers, and source-block fences, while offering optional reflowing of code comments. , and allows users to add project-specific abbreviations via a configuration file. For non-English texts or cases where rule-based splitting is insufficient, it offers optional neural sentence detection using nnsplit for nine languages. Users can mark regions to be skipped during formatting with specific comments, ensuring that poetry, aligned text, and ASCII art remain untouched.

Integration features include a pre-commit hook for enforcing semantic line breaks automatically on each commit, compatibility with editors like Emacs (via Apheleia) and vim through stdin/stdout interfaces, and a bundled Vale style package for flagging lines with multiple sentences. The tool can be set up to auto-format on commit using Git smudge/clean filters, making formatting transparent to collaborators. A one-command setup process detects file formats and generates configuration files, pre-commit hooks, Git attributes, and editor snippets for streamlined adoption.

snapper-fmt is distributed under the MIT License and is provided by TurtleTech ehf. It can be installed using Cargo, Homebrew, pip, Nix, or via a shell script, and is suitable for academic writers and teams seeking cleaner, more manageable version control workflows.