vercel

Breaking Changes

• bytes now crosses the wire as a Uint8Array instead of an ArrayBuffer, and a JavaScript ArrayBuffer decodes to bytearray instead of bytes. (#272)

Features

• A step can now stream output while it runs with get_writable(), and run.readable() reads it back. A workflow body can take the stream and pass it to its steps. The same stream is readable from the TypeScript SDK, the dashboard and workflow inspect stream. (#258)
• Add support to read the encrypted (encr) workflow payloads (AES-GCM) under the new encryption extra. (#279)
• Workflow steps can raise FatalError to skip the remaining retries. The step fails on the attempt that raised it, instead of replaying the same call until max_retries is spent. (#260)

Bug Fixes

• Send and receive workflow queue messages as CBOR, mirroring DualTransport in @workflow/world-vercel. (#265)
• Allow workflow events with specVersion 6. (#280)
• Send the Trusted Sources bypass header on direct workflow-server requests, and derive a non-2xx error from the HTTP status before parsing the body. (#278)

Breaking Changes

• The local workflow world now stores its .workflow-data files as JSON in the same format the TypeScript @workflow/world-local package uses, instead of CBOR. Runs, steps, hooks and events written by either SDK are now readable by the other. Existing .workflow-data directories are not readable in the new format and should be deleted. (#226)
• Workflow payloads now use the devalue wire format of the TypeScript @workflow/core package. (#243)
• Workflow steps now ride the __wkf_workflow_* queue as a stepId on the workflow invoke payload, matching the TypeScript SDK; the separate __wkf_step_* queue is gone. (#251)

Features

• Workflow payloads can now carry native Decimal, UUID, date, time, timedelta and Path, and @serializable (or register_serializable()) is offered for custom classes. (#224)
• Add sync and async clients with typed models for managing project-level routing rules and versions. (#219)

Bug Fixes

• Allow workflows on Python 3.12 and earlier to import uuid by safely exposing platform.system() while continuing to block host-specific platform inspection. (#242)
• Prevent errors when tasks waiting on steps or hooks are cancelled. (#250)
• The Vercel world now honours VERCEL_WORKFLOW_SERVER_URL and WORKFLOW_VERCEL_BACKEND_URL, which previously had no effect in Python, so a preview deployment reaches the same workflow-server as its TypeScript peers. (#248)

Internal

• Use a consistent isolated event-loop lifecycle for workflow execution on Python 3.10. (#242)
• Run workflows on a dedicated event loop that advances execution when the loop becomes idle. (#242)
• Avoid invoking the workflow event loop's idle hook after the loop begins stopping. (#242)

Bug Fixes

• Fix the vercel-sandbox dependency bound, which vercel 0.8.0 published as vercel-sandbox<0.3.0,>=0.3.0 — a range no version can satisfy, so that release could not be installed at all. (#222)

Breaking Changes

• vercel.sandbox is now the promoted Sandbox API that previously lived at vercel.unstable.sandbox. The former vercel.sandbox surface, including AsyncSandbox, Command, AsyncCommand, and TokenProvider, is gone, and vercel.unstable has been removed. Use vercel.sandbox for the async API and vercel.sandbox.sync for the synchronous API. (#195)
• The Sandbox implementation now ships in the separate vercel-sandbox distribution, which vercel depends on, so vercel.sandbox imports keep working without installing anything extra. (#195)
• Workflow and step identifiers now use // between the module and qualified name to match the TypeScript SDK format. (#220)

Features

• Add vercel.functions.wait_until() for post-response asynchronous work that remains attached to the current Python Function invocation. (#218)
• Port from vercel-workers to vercel-queue (#184)

Internal

• Move Vercel SDK tests under the package-local test suite. (#194)

Bug Fixes

• Fix workflows to work with current Vercel workflow-server, and prevent similar breakages in the future. (#190)

• No changes.

Features

• Add an experimental vercel.unstable.sandbox SDK with sync and async sandbox lifecycle, process, filesystem, snapshot, query, and session APIs. (#128) (#172)
• Add streaming read and write support for Sandbox files and process output. (#135) (#172)
• Improve Workflows sandbox execution with configurable cleanup handlers, passthrough modules, namespaced workflows, and more reliable resume/error handling. (#144, #146, #148, #153, #154, #155, #156, #162, #163, #164, #165) (#172)
• Refactor internal HTTP transport handling to support streamed responses, raw bodies, timeouts, retries, and shared token resolution. (#119) (#172)