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Every generated or healed test is delivered as a PR that you review and merge on your terms. You always have full control over what goes into your codebase.

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Your Repo Is the Source of Truth

The mirror works both ways — Checksum reads from your repo AND writes to it via PRs — but your repository is always the source of truth. You can edit tests directly, push new tests, or modify generated code, and Checksum picks up the changes automatically on the next sync. Think of Checksum’s agent as just another member of your team. It opens PRs like any other developer, and you review and merge them. You’re always in control.

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How It Works

Repo Mirror Flow

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Reading from Your Repo

Checksum continuously monitors your connected repositories:
  • Tracks branches and their current state
  • Understands which tests already exist — so it doesn’t generate duplicates
  • Detects changes — when your code changes, Checksum knows which tests might be affected
  • Syncs automatically via webhooks from GitHub or GitLab whenever you push, merge, or update PRs
This means Checksum always has an up-to-date understanding of your test suite and codebase.

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Configuration Mirror

Beyond code, Checksum also mirrors your project configuration — including environment variables, environment settings, and test credentials. When you configure environments in the Checksum web app (environment URLs, login URLs, user credentials), these settings are stored in the cloud and synced down to your test environment via the CLI: 
npx checksumai dotenv --download --api-key=<YOUR_API_KEY>
This ensures that your local development environment, CI pipeline, and Checksum’s agent sessions all use the same configuration. When you update settings in the web app, the next dotenv --download pulls the latest values.
Think of it this way: Checksum mirrors your code (tests ↔ repo) and your config (environment settings ↔ .env file). Both stay in sync automatically.

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Writing to Your Repo

When Checksum generates new tests or heals broken ones, it delivers the changes as pull requests:
  • Each PR contains Playwright test code you can review like any other code change
  • PRs include a clear description of what was generated or healed
  • You review, request changes, or merge — just like any other PR workflow
  • Checksum tracks whether PRs are open, merged, or closed

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What Triggers a Sync?

Checksum stays in sync with your repository through webhooks:
  • Push events — when code is pushed to any branch
  • PR events — when pull requests are opened, updated, merged, or closed
  • Installation events — when the GitHub App permissions change
These webhooks are set up automatically when you install the Checksum GitHub App or configure GitLab integration.

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Example

REPO_MIRROR
When you generate tests for a “User Login” flow, Checksum:
  1. Creates a new branch (e.g., ChecksumAI-generated-test-20260315143022)
  2. Adds the generated .checksum.md story file and .checksum.spec.ts test file
  3. Opens a PR with a description of the test flow
  4. You review the code, run the tests, and merge when satisfied

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Next Steps