Generates a graded comprehension quiz from the current Git branch diff, delivered in the terminal or through Google Forms. Useful for checking that a developer understands the changes before review or merge.
Claude Code
$ npx -y skills add jamestkelly/diffler --agent claude-code
Codex
$ npx skills add jamestkelly/diffler -a codex
Cursor
$ npx skills add jamestkelly/diffler -a cursor
Gemini CLI
$ npx skills add jamestkelly/diffler -a gemini-cli
GitHub Copilot
$ npx skills add jamestkelly/diffler -a github-copilot
OpenCode
$ npx skills add jamestkelly/diffler -a opencode
Windsurf
$ npx skills add jamestkelly/diffler -a windsurf
Prove you understand the diff.
Diffler generates comprehension quizzes from Git branch diffs for Claude Code, OpenCode, and pull-request workflows. Its agent skill collects focused branch context, generates graded questions, and delivers them either as an offline quiz in your local terminal or as a published Google Form.
Diffler is in early development. The repository contains the TypeScript project foundation, versioned quiz-document contract, local branch-context collection, interactive local quiz delivery, Google Forms authentication and publication, and a portable Claude Code and OpenCode skill.
Install dependencies and run all checks:
pnpm install --frozen-lockfile
pnpm check
pnpm build
Run the development CLI:
pnpm start --help
pnpm start context --base main
pnpm start quiz .diffler/quiz.json --context .diffler/context.json
pnpm start publish .diffler/quiz.json --context .diffler/context.json
Run an installed quiz locally, without Google authentication or network access:
diffler quiz .diffler/quiz.json --context .diffler/context.json
Google authentication is optional and needed only for Forms delivery. To
authorize publication, follow the
Google authentication setup, then run
diffler auth login. Maintainers can still select a bring-your-own Desktop
client with --credentials <path>.
Install the packaged agent skill and check local readiness with:
diffler skill install claude --scope user
diffler doctor
See Google Forms publishing for the optional publication flow and manual verification steps. Install the agent workflow using the skill installation guide. Maintainers can inspect and install the exact npm tarball by following the npm publication guide.
The aggregate check command verifies formatting, linting, types, and tests.
CI runs the same checks on pull requests and pushes to main.
The stable Review Gate check and recommended branch protection are documented
in Repository Settings.
Maintainers can verify both canonical Google Cloud environments without making
changes by running pnpm cloud:check; see
Google Authentication.
src/ TypeScript CLI and domain implementation
docs/ Context and quiz contracts
skills/diffler/ Packaged Claude Code and OpenCode skill
.github/workflows/ Continuous integration
MIT. See LICENSE.
Stars on GitHub
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@facebookGenerates a graded comprehension quiz from the current Git branch diff, delivered in the terminal or through Google Forms. Useful for checking that a developer understands the changes before review or merge. Install it with the command on its page. It includes diffler. Its skills do not fire on their own yet. Free and open source.
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