How DiffPal Works

DiffPal is an open-source pull request and merge request review engine that runs in your CI workflow. It standardizes how a repository asks an AI provider for review, validates the response, publishes feedback, writes artifacts, and optionally blocks a merge.

Product Boundary

DiffPal owns the review workflow around the provider:

• resolving the requested base/head range and review scope;
• building the review request;
• validating provider output against changed files and lines;
• rendering summaries, findings, and artifacts;
• publishing to supported code hosts;
• applying the configured gate.

DiffPal is not the model, the provider account, or a mandatory hosted review service.

When a remote provider is configured, DiffPal sends review input to that provider from the CI job. Use Security controls before enabling secret-backed review.

Provider Boundary

The selected provider or ACP-compatible CLI owns model reasoning, model access, provider-specific tools, credentials, sandboxing, and account management. DiffPal chooses a provider through diffpal.provider, sends the review task, and expects structured review output back.

Use Providers and agents for the provider model and Providers for setup pages.

Publisher Boundary

DiffPal publishers turn validated findings into host-native feedback. GitHub, GitLab, and Azure DevOps have native publishers. Custom CI can still produce local artifacts, and can publish through a supported code host when the job has the required host metadata and credentials.

Use the support matrix for supported host outputs.

Repository-Owned Configuration

DiffPal reads .config/diffpal/config.yaml from the repository. That file owns the selected provider, review settings, platform publishing settings, profiles, and gate threshold. CI files install/authenticate the provider and pass host context, but the review policy stays with the repository.

flowchart LR
    A[PR or MR event] --> B[CI job]
    B --> C[Repository DiffPal config]
    C --> D[DiffPal review engine]
    D --> E[Selected provider or ACP agent]
    E --> F[Structured findings]
    F --> G[Publisher]
    F --> H[Artifacts]
    F --> I[Optional gate]

For the first setup path, start with the GitHub quickstart. For supported hosts and outputs, see the support matrix.