difftab

See what your AI coding agent changed — in one tab.

Run one command in your repo. A local page opens with your working-tree diff and branch status — what git status and git diff HEAD would show — read-only, refreshing itself while the agent keeps writing. Close the tab and the process exits.

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Install

npx difftab        # or install it once: npm i -g difftab

Requires Node.js 22 or newer on macOS, Windows or Linux. Zero dependencies.

Usage

cd /path/to/your/repo
difftab

• --no-open — print the URL instead of opening a browser
• -v, --version — print the version and exit
• -h, --help — print help and exit

Running it again in the same repository reuses the running instance.

What you get

• Change list — staged, unstaged, untracked and conflicting files in four groups, with untracked directories expanded to files.
• Diffs, lazily — click a file to load its patch, rendered by diff2html + highlight.js in a VS Code-like theme, side by side until the pane gets too narrow.
• Branch status — branch name, ahead/behind counts, "no upstream", detached HEAD, and an in-progress rebase / merge / cherry-pick / revert / bisect / git am.
• Auto-refresh — a file watcher pushes changes over SSE, falling back to polling where recursive watching would exhaust the inotify quota (and saying so in the UI).
• Exits on its own — 45 seconds after the last tab closes.

Empty repositories, interrupted rebases, linked worktrees, submodules, binary and >5 MB files, renames, and paths with spaces, quotes, CJK or emoji are handled explicitly. difftab is deliberately a viewer: no editing, history, blame or review workflow (out-of-scope list).

Never writes to your repository

Not a best-effort claim: difftab only ever runs read-only git commands — no stage, commit, discard, pull, push, branch or stash. Two gates enforce it on every change: a GIT_TRACE allowlist over every git invocation, and a byte-for-byte comparison of .git before and after. And dist/server/main.js ships unminified, so you can audit it by hand.

Development

pnpm install --frozen-lockfile
pnpm build                       # frontend (Vite) + backend (tsdown)
node bin/difftab.js              # run it against any repository

CONTRIBUTING.md has the dev-server setup, the gates, and the things that fail silently rather than loudly; docs/ holds requirements and design, the single source of truth.

License

MIT