Workflows Overview

Moost Workflows let you model multi-step processes as composable, typed sequences of operations. Instead of tangling business logic into deeply nested functions, you define discrete steps, arrange them into a schema, and let the workflow engine handle execution order, branching, pausing, and resumption.

When to Use Workflows

Workflows are a good fit when your process:

• Has multiple stages that must execute in a specific order
• Needs branching based on runtime data (approve/reject, retry/abort)
• Can be interrupted to wait for user input, external approval, or async events
• Requires auditability — you need to trace what ran, when, and with what data
• Spans time — the process may take minutes, hours, or days to complete

Common examples: user onboarding, order fulfillment, document approval, data import pipelines, multi-step forms.

Core Concepts

Concept	What it does
Steps	Individual units of work — controller methods decorated with @Step
Schemas	Declarative arrays defining execution order, conditions, and loops
Context	Typed shared state that persists across all steps in a workflow
Pause & Resume	Interrupt a workflow to collect input, then continue from where it stopped
Error Handling	Retriable errors that pause instead of fail, enabling graceful recovery
Spies	Observers that monitor step execution for logging, timing, or auditing

How It Works

A typical workflow lifecycle:

1. Define steps as controller methods, each handling one piece of logic
2. Compose a schema that arranges steps with conditions and loops
3. Start the workflow with an initial context object
4. Steps execute in sequence, reading and mutating the shared context
5. Workflow completes — or pauses if a step needs input, then resumes later

start(schemaId, context)
    |
    v
[ step 1 ] --> [ step 2 ] --> { condition? } --yes--> [ step 3a ]
                                    |
                                    no
                                    |
                                    v
                              [ step 3b ] --> done

The workflow output tells you whether it finished, paused for input, or encountered an error — along with the full serializable state you can store and resume from later.

What's Next?

Ready to try it? Head to the Getting Started guide to build your first workflow.