Event Storming

Interactive Workshop Configuration

Use AskUserQuestion to configure the event storming session:

# Question 1: Workshop Mode (MCP: Event Storming methodology)
question: "Which event storming mode do you need?"
header: "Mode"
options:
  - label: "Full Simulation (Recommended)"
    description: "All 5 personas debate in parallel, 6 phases (~15K tokens)"
  - label: "Quick"
    description: "Single analysis pass, no personas (~3K tokens)"
  - label: "Guided"
    description: "Interactive with user, personas on-demand"
  - label: "Codebase Analysis"
    description: "Discover events from existing code structure"

# Question 2: Domain Scope (MCP: DDD bounded context patterns)
question: "How complex is the domain you're exploring?"
header: "Scope"
options:
  - label: "Single Bounded Context"
    description: "One domain area, focused discovery"
  - label: "Multiple Contexts"
    description: "Identify 2-5 bounded context boundaries"
  - label: "Enterprise Domain"
    description: "Comprehensive cross-domain mapping"
  - label: "Unknown"
    description: "Help me determine scope first"

Use these responses to select the appropriate workshop mode and calibrate depth of analysis.

When to Use This Skill

Use this skill when you need to:

Discover domain events for a business process
Identify commands and actors in a system
Find bounded context boundaries
Simulate a multi-stakeholder event storming workshop
Prepare for actual event storming facilitation
Analyze an existing codebase for domain events

Keywords: event storming, domain events, commands, actors, bounded contexts, aggregates, domain discovery, workshop simulation, multi-persona, DDD

What is Event Storming?

Event Storming is a workshop-based method for collaborative domain discovery. Participants use sticky notes to map out:

Events (Orange) - Things that happen in the domain
Commands (Blue) - Actions that trigger events
Actors (Yellow) - Who issues commands
Aggregates (Yellow) - Business entities that handle commands
Read Models (Green) - Information needed for decisions
Policies (Purple) - Business rules and reactions
External Systems (Pink) - Outside integrations
Hot Spots (Red/Pink) - Areas of confusion or conflict

Workshop Modes

This skill supports three modes of operation:

Mode	Description	Token Cost	Use Case
`full-simulation`	All 5 personas debate in parallel, 6 phases	~15K tokens	Comprehensive discovery
`quick`	Single analysis pass, no personas	~3K tokens	Quick domain overview
`guided`	Interactive with user, personas on-demand	Variable	User wants control

Mode Selection Guide

Use full-simulation when:

Starting a new project or major feature
You need comprehensive domain discovery
Multiple perspectives are valuable
Time is less critical than thoroughness

Use quick when:

You need a fast domain overview
Token budget is constrained
Domain is relatively simple
You'll refine later

Use guided when:

You want to drive the process
You have specific questions
You want to invoke specific personas
Interactive exploration is preferred

Multi-Persona Simulation

The full-simulation mode uses 5 specialized agents to simulate different stakeholder perspectives:

Persona Agent	Role	Perspective	Contributions
`domain-expert`	Subject Matter Expert	Deep business knowledge	Domain events, business rules, edge cases
`developer-persona`	Technical Implementation	System constraints	Technical events, integration points
`business-analyst`	Process & Requirements	Process flow	Commands, actors, acceptance criteria
`product-owner`	Product Vision	User value	Priorities, MVP scope, user stories
`devils-advocate`	Challenger	Identify gaps	Hot spots, missing scenarios, contradictions

6 Workshop Phases (Full Simulation)

Phase 1: Chaotic Exploration

All personas brainstorm events independently. No constraints, no ordering.

Orchestration:

Launch 5 parallel Task agents:
- Task(event-storming-persona domain-expert, "Identify all domain events for: {domain}")
- Task(event-storming-persona developer, "Identify technical events for: {domain}")
- Task(event-storming-persona business-analyst, "Identify commands and actors for: {domain}")
- Task(event-storming-persona product-owner, "Prioritize and identify MVP scope for: {domain}")
- Task(event-storming-persona devils-advocate, "Challenge and identify gaps for: {domain}")

Phase 2: Timeline Ordering

Synthesize and order events chronologically. Create the timeline.

Phase 3: Command Discovery

Identify what triggers each event. Map commands to events.

Phase 4: Actor Identification

Map who issues each command. Define roles and systems.

Phase 5: Bounded Context Discovery

Group related events/commands. Identify natural boundaries.

Phase 6: Hot Spot Resolution

Devil's advocate challenges. Resolve conflicts and gaps.

Detailed phase guidance: See references/workshop-facilitation.md

Sticky Note Color Convention

Color	Represents	Example
🟧 Orange	Domain Event	"Order Placed", "Payment Received"
🟦 Blue	Command	"Place Order", "Process Payment"
🟨 Yellow (small)	Actor	"Customer", "Admin", "System"
🟨 Yellow (large)	Aggregate	"Order", "Customer", "Product"
🟩 Green	Read Model	"Order Summary", "Product Catalog"
🟪 Purple	Policy	"When order placed, reserve inventory"
🟫 Pink	External System	"Payment Gateway", "Email Service"
❗ Red/Pink	Hot Spot	Areas of confusion or conflict

Detailed conventions: See references/sticky-note-types.md

Orchestration Pattern

Since Claude Code subagents cannot spawn other subagents, the main conversation orchestrates:

Main Conversation
    ↓
Invokes event-storming skill
    ↓
Skill guides parallel Task tool calls:
    ├── Task(event-storming-persona domain-expert, prompt)
    ├── Task(event-storming-persona developer, prompt)
    ├── Task(event-storming-persona business-analyst, prompt)
    ├── Task(event-storming-persona product-owner, prompt)
    └── Task(event-storming-persona devils-advocate, prompt)
    ↓
Skill synthesizes results with provenance tracking
    ↓
Outputs event catalog with [persona] attribution

Quick Start

Full Simulation Mode

I want to run a full event storming simulation for an e-commerce order management system.

Please:
1. Launch all 5 persona agents in parallel
2. Have them analyze the domain
3. Synthesize their findings
4. Identify bounded contexts
5. Resolve any hot spots

Quick Mode

Give me a quick event storm overview for a subscription billing system.
Focus on the core happy path events.

Guided Mode

Let's do a guided event storming session for a hospital appointment system.
Start with the patient booking journey and I'll guide from there.

Output Format

The event storming session produces a structured event catalog:

# Event Storm: [Domain Name]

## Event Catalog

### [Bounded Context Name]

**Events:**
- [Event Name] [Domain Expert] - [Description]
- [Event Name] [Developer] - [Description]

**Commands:**
- [Command Name] → [Event Name] [Business Analyst]

**Actors:**
- [Actor Name]: [Commands they can issue]

**Aggregates:**
- [Aggregate Name]: [Events it produces]

**Policies:**
- [Policy Name]: [Trigger] → [Action]

## Bounded Contexts Identified

1. [Context Name]
   - Core Domain / Supporting / Generic
   - [Events in this context]

## Hot Spots

- [Issue] - [Resolution or TODO]

Full template: See references/templates/event-storm-output.md

Integration with Other Skills

Event storming connects with:

domain-storytelling - Stories feed into event discovery
modular-architecture - Bounded contexts become modules
fitness-functions - Module isolation tests
adr-management - Document bounded context decisions

Workflow:

Domain Storytelling → Event Storming → Modular Architecture
(understand "what")   (design "how")   (implement "where")

Best Practices

Start with events - Events are facts, commands are debatable
Use past tense - "Order Placed" not "Place Order"
Explore boundaries - Events help find module boundaries
Embrace chaos - Initial brainstorming should be messy
Track provenance - Know which perspective each insight came from
Resolve hot spots - Don't leave conflicts unaddressed

References

references/workshop-facilitation.md - Phase orchestration and timing
references/persona-prompts.md - Prompt templates for each persona
references/sticky-note-types.md - Color conventions and usage
references/bounded-context-discovery.md - Context identification patterns
references/templates/event-storm-output.md - Output format with provenance

Version History

v1.0.0 (2025-12-22): Initial release
- Multi-persona simulation with 5 agents
- Three workshop modes (full, quick, guided)
- 6-phase workshop structure
- Provenance tracking for insights
- Integration with domain-storytelling and modular-architecture

Last Updated

Date: 2025-12-22 Model: claude-opus-4-5-20251101