Migrating Workflow SDK 4.x to 5.0

Workflow SDK 5.0 keeps the programming model from 4.x. "use workflow" / "use step", start(), getRun(), hooks, webhooks, streams, sleep(), retries, and the event log are unchanged, so most application code compiles as-is.

The breaking changes are concentrated in three places:

1. Runtime entrypoints (workflow/api, workflow/runtime) — two exports removed.
2. The World interface — only relevant if the app implements a custom World or calls getWorld() directly.
3. Build integrations — @workflow/nest subpaths, and private compiler subpaths that were never public.

Do not rewrite workflow or step bodies. If you find yourself restructuring business logic, you have gone outside this migration.

Intake

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