Preview generations

FreeAvailable on every planPreview Generations are unlimited for the Project on every plan. Free Targets include 25 operations; review covers the complete Spec.

A Preview Generation shows the packages a source pull request would produce before you merge it. Typeship compares the base and proposed Specs, checks compatibility and Diagnostics, and generates each selected Target. Changes in referenced OpenAPI or GraphQL files also trigger a review.

Preview Generations require a GitHub repository Spec. Drafts, base-branch edits, synchronizations, reopens, and typeship:breaking-approved label changes all recompute the result.

What the pull request shows

Typeship posts one comment on the source pull request and updates it as the pull request changes. The comment includes:

• one row for each Target and whether it generated;
• API compatibility;
• the Diagnostic policy result;
• the Spec entrypoint and the commit it analyzed;
• breaking changes grouped by category, with affected methods collapsed;
• compatible additions and resolved findings; and
• a note when the report or a Free Target is truncated.

Typeship also sets two commit statuses:

• Typeship API Review combines compatibility with the Diagnostic policy. An approved break is still reported as breaking; the typeship:breaking-approved label records that the repository accepted it.
• Typeship Previews passes only when every configured CLI, MCP, and SDK Target generated.

Both statuses appear on every pull request in a linked source repository. A pull request that does not change the Spec passes both without a comment. When several Projects share a repository, each posts its own report, and each status shows the worst result.

For automation, read the versioned typeship-result record in the comment. It contains the commit, Spec entrypoint, compatibility, approval, counts, and Target states. Display text can change; do not use it for programmatic decisions.

Compatibility

Breaking changes include removed methods or fields, newly required inputs, changed request or response types, changed authentication or pagination, and documented error-contract changes. Additions with optional inputs, documentation, and deprecation changes remain compatible.

OpenAPI and GraphQL use the same compatibility and release rules. Source pull requests never change package versions. After the source change merges, each destination pull request compares the accumulated changes with the last release merged in that destination, and Typeship Release checks the version.

When a pull request changes

• Spec patches apply to both the head and base, so the report shows only the source change.
• Each Target's result is reported separately. One failed Target does not hide the others.
• A newer push replaces the report for an older one.
• Reverting a change updates the existing report.
• Typeship reads public forks without running their code. A private fork Typeship cannot read fails with an explicit message.
• If the pull request renames the Spec entrypoint, the report names the path to update in the Project.