---
description: Facilitate event storming sessions to discover domain events and workflows
triggers:
  - manual
  - discovery:events
agents:
  - domain-decomposer
  - architect
---

# Event Storming Workflow

Discover domain events and model business processes.

## Prerequisites
- [ ] Domain experts available
- [ ] Whiteboard/digital collaboration tool
- [ ] Business process documentation

## Phase 1: Big Picture Event Storming

### Step 1.1: Identify Domain Events
```yaml
agent: domain-decomposer
action: discover
focus: domain_events
notation: orange_stickies
guidelines:
  - Past tense verbs (OrderPlaced, PaymentReceived)
  - Business-meaningful names
  - Temporal ordering
```

### Step 1.2: Timeline Organization
```yaml
agent: domain-decomposer
action: organize
steps:
  - Place events chronologically
  - Identify parallel flows
  - Mark pivotal events
  - Note questions and hotspots
```

## Phase 2: Process Modeling

### Step 2.1: Add Commands
```yaml
agent: domain-decomposer
action: model
element: commands
notation: blue_stickies
pattern:
  - Command triggers Event
  - Name as imperative (PlaceOrder)
  - Link to triggering event
```

### Step 2.2: Add Actors
```yaml
agent: domain-decomposer
action: model
element: actors
notation: yellow_stickies
types:
  - Users (roles)
  - External systems
  - Time (scheduled events)
```

### Step 2.3: Add Policies
```yaml
agent: domain-decomposer
action: model
element: policies
notation: purple_stickies
pattern: "When [Event] then [Command]"
examples:
  - "When OrderPlaced then ReserveInventory"
  - "When PaymentFailed then CancelOrder"
```

## Phase 3: Aggregate Discovery

### Step 3.1: Group Related Concepts
```yaml
agent: domain-decomposer
action: discover
element: aggregates
notation: yellow_boundary
criteria:
  - Commands that modify together
  - Events from same source
  - Consistency boundary
```

### Step 3.2: Define Aggregate Boundaries
```yaml
agent: architect
action: define
boundaries:
  - Invariants protected
  - Transaction scope
  - Entity relationships
outputs:
  - aggregate_diagram
  - invariant_rules
```

## Phase 4: Bounded Context Identification

### Step 4.1: Identify Context Boundaries
```yaml
agent: domain-decomposer
action: discover
element: bounded_contexts
indicators:
  - Language changes
  - Different stakeholders
  - Different models for same concept
  - Natural team boundaries
```

### Step 4.2: Map Context Relationships
```yaml
agent: architect
action: map
relationships:
  - Upstream/Downstream
  - Conformist/Anti-corruption Layer
  - Partnership
  - Customer/Supplier
```

## Phase 5: Documentation

### Step 5.1: Create Event Catalog
```yaml
agent: domain-decomposer
action: document
outputs:
  - event_catalog:
      - name
      - description
      - payload_schema
      - producers
      - consumers
```

### Step 5.2: Create Process Diagrams
```yaml
agent: architect
action: generate
outputs:
  - process_flow_diagrams
  - aggregate_diagrams
  - context_maps
```

## Outputs
- [ ] Domain event catalog
- [ ] Command list
- [ ] Aggregate definitions
- [ ] Bounded context map
- [ ] Process flow diagrams

## Quality Gates
- All events have clear ownership
- Aggregates have defined invariants
- Context boundaries are explicit
- Ubiquitous language documented
- Stakeholders validated model