Grain: a blame view for AI-written code

Field notes

Grain combines a git post-commit hook with a Claude Code PostToolUse hook, allowing edits to be recorded at the source rather than inferred from finished code. The homepage says the system stores content hashes instead of text and attaches evidence through git notes. Its self-test covers 91 commits and reports 98% AI-assisted work, while separately identifying only 16% of lines as attested line by line, making the limits of its evidence visible alongside the headline measurement.