Streams are addressed as { projectId, path }. Use a concrete project id for project-local streams and projectId: null for deployment-wide streams (encoded as the reserved global.iterate host in Durable Object names — src/domains/durable-object-names.ts). Event payloads should include projectId only when that fact itself names a project; processor birth certificates keep addressing out of their payload and contain only immutable domain birth facts (often { config }, or {} for an existence-only birth such as Agent).