Architecture

The Rebase control plane owns workspace scoping, source snapshots, immutable target versions, run records, and SDK polling. Execution is routed by run_type: user code selects quick, quick_shared, or long, and the platform maps that intent to concrete Cloud Run infrastructure. The resolved path is recorded on each run as the internal execution_backend field.

Function and model runs dispatch directly from the API layer. quick invokes a private isolated Cloud Run service — one service per function, one tagged revision per immutable version — synchronously, so the service is warm after the first call. quick_shared invokes the shared Cloud Run runner service with no per-function provisioning. long starts one Cloud Run Job execution per run.

Workflow runs remain Prefect-backed. Rebase runs a self-hosted Prefect API on Cloud Run; the SDK compiles step calls into a stored step_graph, and the runner executes that graph as Prefect tasks, writing StepRun records as each node starts and completes. For quick workflows, a warm Cloud Run service worker picks up manual runs; for long workflows (and all scheduled runs), a worker creates one Cloud Run Job per run.

All execution paths are Cloud Run. The former Modal, GKE-Prefect, and Prefect Cloud routes have been removed.