event-storm

event-storm is a skill for Claude Code, Codex from DarrenLyons/agentic-ddd. It costs 74 tokens per session (12,733 once invoked), scanned A, original, MIT.

A guided workshop for mapping how a business or product works. DDD means Domain-Driven Design, an approach that shapes software around the real-world area it serves.

In plain words
What is it for?
Use it to map events, group related behavior, define system areas, create a shared glossary, and record key design decisions.
Why use it?
It helps a team resolve disagreements about terms, responsibilities, and system boundaries before major development begins.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/darrenlyons/agentic-ddd/event-storm
Any agent
npx skills add DarrenLyons/agentic-ddd --skill event-storm
Clone the repo
git clone --depth 1 https://github.com/DarrenLyons/agentic-ddd

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for event-storm

README.md
[![agentmods](https://agentmods.dev/badge/skills/darrenlyons/agentic-ddd/event-storm.svg)](https://agentmods.dev/skills/darrenlyons/agentic-ddd/event-storm)
Your own site
<a href="https://agentmods.dev/skills/darrenlyons/agentic-ddd/event-storm"><img src="https://agentmods.dev/badge/skills/darrenlyons/agentic-ddd/event-storm.svg" alt="Measured on agentmods" height="20"></a>
Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 12,733 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00074 $0.12733
Opus 5 $0.00037 $0.06366
Sonnet 5 $0.00015 $0.02547
Haiku 4.5 $0.00007 $0.01273

Measured 5d ago against content hash 0a11d91c9f54, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

event-storm scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

toolkit/skills/event-storm/SKILL.md · 948 lines

How it starts

The opening of the file, as written. The whole thing — 948 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Event Storming Facilitator

Facilitates a DDD event storming exercise to produce a shared domain model. Use when the team needs to agree on aggregate boundaries, bounded contexts, or ubiquitous language for a new or contentious area of the system.

When to use

  • Aggregate / bounded-context disagreement (the model is being argued at the wrong altitude — naming aggregates without enumerating events)
  • New product area being added with no existing model
  • Major refactor before code lands
  • Ubiquitous language drift (terms being used inconsistently)

When NOT to use:

  • Bug fixes (use a focused bug-fix workflow)
  • Single-feature work where the model is already clear
  • Vocabulary-only fixes (just update your project glossary)

Modes

/event-storm <slug> — kick off a new storm. Defaults: focused scope, in-harness architecture. /event-storm continue — resume an in-flight exercise from its last completed phase or stage. /event-storm wrap — finalise deliverables.

A <slug> is a short kebab-case identifier (e.g. subscription-lifecycle, whole-product). Used for folder/file naming.

Flags

  • --mode=focused | big-picturescope. Focused (default) targets a known bounded context and runs Phases 0–5. Big-picture targets the whole product to discover contexts and runs Phases 0–2 plus context discovery.
  • --arch=in-harness | out-of-band | hybridarchitecture. In-harness (default) uses an agent team with full project context (reference shape: Claude Code agents; equivalent in any harness with multi-agent or multi-context support). Out-of-band uses one isolated dispatch per role from a clean cwd for genuine independence (reference command: claude -p; equivalent for other harnesses). Hybrid runs out-of-band positions first, then loads them into the in-harness team for stress-testing.

Scope and architecture are independent. Any combination is valid; some make more sense than others — see selection below.

Mode selection (scope)

Read the full file on GitHub · 948 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 948 lines · 74 tokens per session scan A 0a11d91c9f54

Subscribe to this mod's changes

event-storm is a skill published in the GitHub repository DarrenLyons/agentic-ddd (2 stars, last pushed 4mo ago), licensed MIT. It adds 74 tokens to every session and 12,733 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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