Welcome to Stem

Stem is a Dart-native toolkit for background tasks and durable workflows. A task is a unit of work a worker can retry. A workflow is an orchestrated program whose named checkpoints and waits can be resumed from a store.

Choose your first path

You need to…	Start here
Run a typed, multi-step process with sleep or events	Hosted workflow quick start
Put independent jobs on a queue	Generated task first steps
Decide between memory, Redis, Postgres, or SQLite	Choosing a backend

The function-first API is WorkflowHost: define a HostedWorkflow, submit typed input, and await a HostedRun result. The host is an application facade, not a second execution engine.

Source checkouts and published packages

The documentation site is built from this repository, while dart pub add stem resolves the latest published package. A checkout can contain APIs that are not in the published release yet. If an example does not resolve in a published app, either use the release's API documentation or depend on a specific source path while evaluating the checkout:

dependencies:
  stem:
    path: ../packages/stem

Do not copy internal package:stem/src/... imports from repository tests or examples into application code; use the public exports documented here.

The execution model

For tasks, the path is producer → broker → worker → result backend. WorkflowHost.inMemory packages the workflow app, worker, and in-memory store for a small process-local demo. It starts the app for you and owns it until close().

In-memory state is not restart-durable. For production, create a host with WorkflowHost.create and an app factory that configures a persistent adapter. Re-register the same executable workflow definitions after a restart and use observe with a saved run ID; observing does not submit a second run.

What to remember

• Delivery and execution are at least once. Checkpointing reduces repeated work, but external effects still need idempotency keys or deduplication.
• context.step runs a local Dart callback. It is a workflow checkpoint, not a remote activity or a new worker process.
• host.close() stops local observation and closes resources it owns; it does not cancel persisted runs or forcibly interrupt Dart code.

Next: follow Quick Start, then read First Steps if your app also has generated tasks.