seendiff

When an AI coding agent rewrites forty files in one pass, the ordinary pull-request diff stops being a review tool. seendiff is an open-source diff viewer built for exactly that problem: it shows whole changed files rather than isolated hunks, and it keeps a persistent record of which blocks you have already seen and which you have explicitly marked as reviewed.

A minimap runs down the side of each file, so review progress is something you read at a glance — seen, unseen and still-unreviewed are distinct states, and they survive closing the window, switching branches, or a rebase landing underneath you. Search covers every changed file at once, the interface is fully keyboard-driven, and six colour themes ship in the box, including solarized light and dark.

A walkthrough mode lets the coding agent narrate its own change step by step, so a review can start from the agent's account of what it did rather than from a wall of red and green.

Everything runs on your machine. Typing seendiff inside any git repository starts a localhost server and opens your browser; there are no accounts, no telemetry, and no network calls outside localhost. The tool is roughly 4,000 lines of Python on FastAPI and SQLite with no build step, and it is written for scale — a 40,000-line file still scrolls smoothly.

Requirements: Python 3.10 or newer plus git, on macOS, Linux or Windows. Install with uv tool install git+https://github.com/acme-dot-bot/seendiff. Free and MIT licensed.