Event Store Design
wshobson/agents
Designs event stores for event-sourced systems: requirements, a comparison of EventStoreDB, PostgreSQL, Kafka, DynamoDB and Marten, and stream and versioning practices.
“Designs systems using Event Modeling.”
Apache-2.0Auto-check passed
Install Event Modeling
$ npx skills add lexler/skill-factory --skill event-modeling -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install lexler/skill-factory event-modeling --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .claude/skills && cp -r skills-src/output_skills/design/event-modeling .claude/skills/event-modeling && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "event-modeling" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/design/event-modeling into .claude/skills/event-modeling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "event-modeling", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/lexler/skill-factory/tree/main/output_skills/design/event-modelingType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add lexler/skill-factory --skill event-modeling -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install lexler/skill-factory event-modeling --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .agents/skills && cp -r skills-src/output_skills/design/event-modeling .agents/skills/event-modeling && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "event-modeling" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/design/event-modeling into .agents/skills/event-modeling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "event-modeling", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add lexler/skill-factory --skill event-modeling -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install lexler/skill-factory event-modeling --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/output_skills/design/event-modeling .cursor/skills/event-modeling && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "event-modeling" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/design/event-modeling into .cursor/skills/event-modeling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "event-modeling", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/lexler/skill-factory.git --path output_skills/design/event-modeling--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add lexler/skill-factory --skill event-modeling -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install lexler/skill-factory event-modeling --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/output_skills/design/event-modeling .gemini/skills/event-modeling && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "event-modeling" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/design/event-modeling into .gemini/skills/event-modeling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "event-modeling", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install lexler/skill-factory event-modelingInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add lexler/skill-factory --skill event-modeling -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .github/skills && cp -r skills-src/output_skills/design/event-modeling .github/skills/event-modeling && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "event-modeling" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/design/event-modeling into .github/skills/event-modeling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "event-modeling", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add lexler/skill-factory --skill event-modeling -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install lexler/skill-factory event-modeling --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/output_skills/design/event-modeling .opencode/skills/event-modeling && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "event-modeling" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/design/event-modeling into .opencode/skills/event-modeling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "event-modeling", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
event-modeling- GitHub stars
- 239
- Token cost
- ~1.6k tokens
- SKILL.md length
- 508 words
- Files
- 4 (incl. references)
- Skills in repo
- 25
- Repo updated
- First seen
- Licence
- Apache-2.0
At a glance
- Works in 4 steps: Understand the Domain → High-Level Model → Slice Detail → …
- SKILL.md covers What Event Modeling Produces, Slice Types, Conversational Design Process and Output Format, plus 2 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
About this skill
Event Modeling is a skill in lexler/skill-factory (239 stars). Its SKILL.md is about 1.6k tokens, with 3 other files in the folder (references). Licence: Apache-2.0.
Workflow steps
4 steps, taken from the step headings in SKILL.md.
What it can do on your machine
Read from SKILL.md and the folder at commit 8017333. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are markdown).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Event Modeling loads about 1.6k tokens when it runs, and up to ~2.5k if it reads all its reference files. Until then it costs about 13 tokens; SKILL.md has 508 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from lexler/skill-factory at commit 8017333, republished under its Apache-2.0 licence (© lexler). 508 words, ~1,591 tokens.
Download SKILL.mdSave it as
.claude/skills/event-modeling/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.- name
- event-modeling
- description
- Designs systems using Event Modeling.
STARTER_CHARACTER = 🗺️
What Event Modeling Produces
A set of vertical slices that fully describe a system's behavior. Each slice is independently implementable and testable. The model uses business language throughout — no infrastructure or technical terms.
┌─────────────────────────────────────┐
│ Event Model │
│ │
│ ┌───────────┐ ┌───────────┐ │
│ │ Slice 1 │ │ Slice 2 │ ... │
│ │ STATE_ │ │ STATE_ │ │
│ │ CHANGE │ │ VIEW │ │
│ └───────────┘ └───────────┘ │
│ │ ▲ │
│ │ (events) │ │
│ └──────────────┘ │
└─────────────────────────────────────┘Slice Types
Three types. Every behavior in the system fits one:
STATE_CHANGE — user does something
- Screen → Command → Event
- Command produces one or more events
- May have error events for failure paths
STATE_VIEW — system shows something
- Events → Read Model → Screen
- Read model aggregates data from one or more events
AUTOMATION — system reacts to something
- Event → Processor → Command → Event
- Background process, no user interaction
See references/slice-types.md for element rules, dependency patterns, and naming conventions.
Conversational Design Process
Work with the user through these phases. Move at the user's pace — they might want to go deep on one slice before seeing the full picture.
Phase 1: Understand the Domain
Identify aggregates (core business entities), actors, and high-level use cases. Ask about the business processes, not technical implementation.
Phase 2: High-Level Model
Draft all slices without field details. Show the flow between them — which events feed which read models, which screens lead to which commands. This is the "map" of the system.
Format as a markdown document with one section per slice. Include slice type, aggregate, elements, and how slices connect.
Phase 3: Slice Detail
Walk through one slice at a time. For each:
- Define fields with types and example values
- Identify business rules (not simple validations — real domain rules)
- Write specifications as Given/When/Then scenarios
Phase 4: Executable Specifications
Turn specifications into approval fixture files using the bdd-with-approvals skill. That skill teaches how to:
- Design scannable fixture formats adapted to the domain
- Structure input/output for human validation
- Build parsers and formatters
Read that skill when it's time to design fixtures. The event model specs (Given events / When command / Then events) map naturally to the approved fixture pattern.
Show full SKILL.md (201 more words)Show less
Analyzing Existing Code
When working with an existing codebase instead of greenfield:
- Read the code to extract domain concepts
- Map existing operations to slice types (writes → STATE_CHANGE, reads → STATE_VIEW, background → AUTOMATION)
- Put code references (class names, packages) in element descriptions
- Extract specs from unit tests and comments
Output Format
Produce markdown, not JSON. Design for human readability — someone should look at the model and understand the system.
Write model artifacts to files. Ask the user where they want them (e.g., docs/event-model.md). Update the files as the model evolves through conversation.
High-Level Model
One document showing all slices and their relationships:
# [System Name] Event Model
## Aggregates
- Owner — pet owners who use the clinic
- Pet — animals registered to owners
## Slices
### Register Owner [STATE_CHANGE]
Aggregate: Owner
Screen: Owner Registration Form
Command: Register Owner → Event: Owner Registered
Error: → Owner Registration Failed
### View Owner Profile [STATE_VIEW]
Aggregate: Owner
Events: Owner Registered, Pet Registered → Read Model: Owner Profile
Screen: Owner Profile
### Notify Vet of New Patient [AUTOMATION]
Trigger: Pet Registered → Processor: New Patient Notifier
Command: Send Notification → Event: Vet NotifiedDetailed Slice
Per-slice detail includes fields and specifications:
## Register Owner [STATE_CHANGE]
Aggregate: Owner
### Command: Register Owner
firstName: String — "George"
lastName: String — "Franklin"
address: String — "110 W. Liberty St."
city: String — "Madison"
telephone: String — "6085551023"
### Event: Owner Registered
ownerId: UUID — <generated>
firstName: String — "George"
lastName: String — "Franklin"
address: String — "110 W. Liberty St."
city: String — "Madison"
telephone: String — "6085551023"
### Event: Owner Registration Failed
errors: Map — {"lastName": "required"}
### Specifications
#### Successfully register with valid data
Given: (no prior state)
When: Register Owner
firstName: George, lastName: Franklin
address: 110 W. Liberty St., city: Madison
telephone: 6085551023
Then: Owner Registered
ownerId: <generated>, firstName: George, lastName: Franklin
#### Fail when required fields missing
Given: (no prior state)
When: Register Owner
firstName: George, city: Madison
Then: Owner Registration Failed
errors: {address: required, telephone: required}
#### Business rules
- All fields mandatory: firstName, lastName, address, city, telephone
- Telephone must be numeric, max 10 digitsThese are defaults. Adapt the format to the domain — what matters is that a person can scan it and quickly validate correctness.
Anti-Patterns
- Technical language in element names ("insertOwnerRecord" → "Register Owner")
- Skipping STATE_VIEW slices — every query/display is a slice
- Circular dependencies between elements
- Specs that test simple validation ("must be a number") instead of business rules
- Jumping to fixture format before the model is understood
- Combining multiple commands in one slice — one command per STATE_CHANGE
See Also
- For executable test specifications: invoke the
bdd-with-approvalsskill - For approval testing mechanics: invoke the
approval-testsskill
© lexler, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 3 other files (references) in output_skills/design/event-modeling of lexler/skill-factory.
- SKILL.md
- credits.md
- disclaimer.md
- references/slice-types.md
Open the folder on GitHubat commit 8017333
Compare with similar skills
Event Modeling next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Event Modeling this skilllexler/skill-factory | 239 | — | ~1.6k | Automated safety check: Pass | Apache-2.0 | |
| Event Store Designwshobson/agents | 40k | 9 repos | ~828 | Automated safety check: Pass | MIT | |
| Power Bi Model Design Reviewgithub/awesome-copilot | 40k | 1 repos | ~2.8k | Automated safety check: Pass | MIT | |
| Design Systemaffaan-m/ECC | 275k | — | ~698 | Automated safety check: Pass | MIT | |
| Design Guidepaperclipai/paperclip | 99k | 1 repos | ~3.1k | Automated safety check: Pass | MIT | |
| Design Audit Against Rams' Principlesthedotmack/claude-mem | 98k | — | ~4.6k | Automated safety check: Pass | Apache-2.0 |
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Questions about Event Modeling
How do I install Event Modeling in Claude Code?
Run `npx skills add lexler/skill-factory --skill event-modeling -a claude-code`. Or copy the skill folder (output_skills/design/event-modeling in lexler/skill-factory) into .claude/skills/event-modeling in your project. Claude Code loads it when a task matches its description.
How do I install Event Modeling in Codex?
Run `npx skills add lexler/skill-factory --skill event-modeling -a codex`. Or copy the skill folder (output_skills/design/event-modeling in lexler/skill-factory) into .agents/skills/event-modeling in your project. Codex loads it when a task matches its description.
Can I use Event Modeling in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add lexler/skill-factory --skill event-modeling -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/event-modeling, .gemini/skills/event-modeling, .github/skills/event-modeling and .opencode/skills/event-modeling in your project.
What does Event Modeling need to run?
SKILL.md names no scripts, command-line tools or credentials: Event Modeling is instructions for the agent only.
Does Event Modeling access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Event Modeling safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Event Modeling use?
Event Modeling is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Event Modeling use?
About 1.6k tokens (SKILL.md is roughly 6.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 910 tokens, read only when the agent opens those files.
What are the alternatives to Event Modeling?
Skills that share tags, products or a category with Event Modeling: Event Store Design (wshobson/agents, 40k stars), Power Bi Model Design Review (github/awesome-copilot, 40k stars), Design System (affaan-m/ECC, 275k stars) and Design Guide (paperclipai/paperclip, 99k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Event Modeling?
lexler (a GitHub user) maintains it in lexler/skill-factory, which has 239 GitHub stars. The repository holds 25 skills in this directory. The repository was last updated on August 26, 2026.
Source: lexler/skill-factory on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.