Diffsplain

Review a Git diff one file at a time, with a short coding agent note beside each patch.

Use

Run from a Git checkout:

npx diffsplain

The command opens a local page and compares the checkout with its default branch. It starts at port 2299 and uses the next free port when needed. You need Node.js 22.13 or newer and a signed-in Codex, Claude, Copilot, or OpenCode CLI. Diffsplain tries them in that order. Pull requests also need a signed-in GitHub CLI. Cursor reviews stay disabled because Cursor Agent has no supported read-only, no-network, no-tool mode.

Common targets:

npx diffsplain --pr 198
npx diffsplain owner/repo --branch feature/my-change
npx diffsplain --worktree
npx diffsplain --base BASE_REF --head HEAD_REF

Check Git, the GitHub CLI, and each supported coding agent:

npx diffsplain doctor

Arguments:

Argument	Use
doctor	Show dependency paths, versions, and readiness.
REPO, --repo PATH|URL|OWNER/REPO	Select a local or remote repo.
--pr NUMBER|URL	Review a GitHub pull request.
--branch NAME	Compare a remote branch with its default branch.
--worktree	Review tracked and untracked changes against HEAD.
--base REF --head REF	Review an exact local range.
--agent NAME, --no-agent	Choose a coding agent, or show a plain diff.
--model NAME	Choose the model used for notes.
--reasoning LEVEL	Set minimal, low, medium, high, or xhigh.
--batch-size COUNT	Set the most files per agent pass. The default is 12; large patches use smaller batches.
--jobs COUNT	Set agent passes to run at once. The default is 3.
--force	Regenerate all agent notes instead of using cached notes.
--support-record	Print a safe JSON record if the review fails.
--support-record-file FILE	Write one safe JSON record if the review fails.
--remote NAME|URL	Choose the Git remote. The default is origin.
--port NUMBER	Choose an exact local port. The default starts at 2299.
-h, --help	Show command help.
-v, --version	Show the installed version.

Local development

corepack enable
corepack pnpm run setup
corepack pnpm run dev

Run the public CLI from this checkout:

corepack pnpm run diffsplain -- --worktree
corepack pnpm run diffsplain -- doctor
corepack pnpm run doctor

Install Chromium once, then run the checks:

corepack pnpm run test:browser:install
corepack pnpm run check
corepack pnpm run test:browser

Run the Blume docs:

corepack pnpm run docs:dev

More guides are in docs/.