elephant-goldfish-model: Open Source AI Development Platforms

What is elephant-goldfish-model?

Elephant Goldfish Model (EGM) is an open-source, Apache-2.0 plugin for AI coding agents that helps software engineers draft specifications with a context-rich agent and review them with fresh, zero-context subagents before writing code.

What it is

EGM is a set of agent skills packaged as a plugin for coding agents such as Antigravity, Claude Code, and Codex. It installs into the host agent rather than running as a separate application. Elephant holds project context, requirements, and earlier decisions to explore the problem and draft a specification; Goldfish reviewers examine the draft and referenced source material without the earlier conversation. The human resolves architectural trade-offs and approves the design before implementation.

The problem is that a design drafted and reviewed inside one long agent session inherits that session's assumptions, letting unstated requirements and blind spots survive into implementation. EGM forces a zero-context review by fresh subagents and stops the review if the host cannot create them. It replaces the default pattern of asking one coding-agent session to both draft and review a design for features that need design decisions; for a small, clear bug fix, the README points to the normal coding workflow.

Key capabilities

Role-separated design: Elephant drafts from project context, while Goldfish reviewers see the document and referenced source material without the earlier conversation.
Seven skills cover Brainstorm, Draft, Resolve, Bootstrap, Review, Review loop, and Drift report, each usable on its own.
The "/egm-brainstorm" skill saves the agreed direction in "concepts_brief.md"; "/egm-draft" turns it into "design_draft.md", pausing after each section for feedback.
"/egm-review design_draft.md" runs fresh reviewers across five stages to check the design, its clarity, its fit with the code, and its implementation plan, with selectable findings.
Review loop runs a configured reviewer group for a specific task, and Drift report compares checked-in documents with current source code.
Bootstrap creates or updates documentation for an existing codebase, and host integration covers "agy plugin install", "/egm:" commands in Claude Code, and a Codex skill picker.

Who uses it and how

Thousands of Google engineers use EGM to draft specs with deep-context agents and stress-test them with zero-context subagents before writing code.
Engineers in Claude Code, Codex, or Antigravity invoke EGM inside an existing project; Claude Code uses "/egm:" commands and Codex uses the skill picker.
Teams designing features with open questions, such as webhook delivery failure handling or duplicate event arrival, move from brainstorm to draft to review to settle requirements and trade-offs.
Maintainers use Bootstrap for existing codebase documentation and Drift report to compare checked-in documents with current source.
Review leads can run a Review loop with a configured reviewer group; the session must create fresh subagents, and EGM stops the review if it cannot.

Getting started

Install the complete plugin through your coding agent: Antigravity uses "agy plugin install https://github.com/google/elephant-goldfish-model"; Claude Code uses "claude plugin marketplace add google/elephant-goldfish-model" then "claude plugin install egm@egm"; Codex uses "codex plugin marketplace add google/elephant-goldfish-model" and "codex plugin add egm@egm". Start a new session after installation, and see "docs/harnesses.md" for Claude Cowork and ChatGPT Work setup.

How it compares

EGM is not a standalone coding agent; it is a plugin that runs inside Antigravity, Claude Code, and Codex and depends on their subagent capabilities. No similar design-review tool is named in the facts, so it stands alone in this registry.

When to use it — and when not to

EGM fits features that need design decisions before implementation; the README sends small, clear bug fixes to a normal coding workflow. A team whose coding agent cannot create fresh subagents should not pick it, because Goldfish reviews require those contexts and EGM stops when they are unavailable. A review also does not replace tests or human judgment, so approval and verification remain human responsibilities.

project readme (upstream, from github) — read inline

Design with an elephant. Review with a goldfish.

Install · Quickstart · Documentation · Website

Thousands of Google engineers use EGM, an open-source plugin, to draft specs with deep-context agents and stress-test them with zero-context subagents before writing code.

Elephant holds your project context and drafts the specification. Goldfish reviewers examine the draft and referenced source material without the earlier conversation, helping expose unstated assumptions and blind spots. You make the architectural trade-offs and approve the specification before implementing.

Use it when a feature needs design decisions before implementation. For a small, clear bug fix, use your normal coding workflow.

Install

Choose your coding agent. Install the complete plugin so its skills can read the reviewer prompts and document standards.

Antigravity

agy plugin install https://github.com/google/elephant-goldfish-model

Claude Code

claude plugin marketplace add google/elephant-goldfish-model
claude plugin install egm@egm

Codex

codex plugin marketplace add google/elephant-goldfish-model
codex plugin add egm@egm

Start a new session after installation. For Claude Cowork and ChatGPT Work, see the setup guide.

Try your first design

Open your project in your coding agent and choose a feature that needs design decisions. This example adds webhook delivery: what should happen when a delivery fails, or the same event arrives twice?

Use the commands below in Antigravity. In Claude Code, use the /egm: prefix, for example /egm:egm-brainstorm. In Codex, select the corresponding EGM skill from the skill picker. Brainstorming and review require a session that can create fresh subagents.

Explore the idea

/egm-brainstorm Add webhook delivery to this project.

Discuss requirements and trade-offs with the agent. Fresh reviewers challenge the proposal, and the agent saves the agreed direction in concepts_brief.md.

Draft the specification

/egm-draft

The agent turns the brief into design_draft.md, pausing after each section for your feedback in chat.

Review the draft

/egm-review design_draft.md

Use the draft path returned by the agent.

Fresh reviewers check the design, its clarity, its fit with the code, and its implementation plan. Choose which findings to address. When you approve the design, ask your coding agent to implement it.

See the workflow guide for the full process, including saving approved specifications under docs/designs/.

How it works

Role	Context	Responsibility
Elephant	Your project, requirements, and earlier decisions	Explore the problem and draft the specification.
Goldfish	The document and its referenced source material, without the earlier conversation	Find missing assumptions, unclear requirements, and implementation risks.
You	The goals and constraints that matter	Resolve trade-offs, approve the design, and decide what to build.

Goldfish reviews require fresh subagent contexts. If your agent cannot create them, EGM stops the review. A review does not replace tests or human judgment. See supported environments and verification limits.

Choose a skill

You can use each skill when you need it. You do not have to follow the full sequence.

Skill	Use it to…
Brainstorm	Test an idea and write a concept brief.
Draft	Turn a brief or existing notes into a design document.
Resolve	Work through review findings and agree on changes.
Bootstrap	Create or update documentation for an existing codebase.
Review	Review a design with fresh agents across five stages.
Review loop	Run a configured group of reviewers for a specific review task.
Drift report	Compare checked-in documents with the current source code.

Learn more

Getting started: the workflow and project layout.
Setup: installation, agent capabilities, and known limits.
Architecture: how skills and reviewers fit together.
Testing: checks, execution records, and verification limits.
Dave Rensin’s original essay: the ideas behind EGM.

Contribute

Read contributing for PRs, issues for bugs, and discussions for questions.

License

Apache 2.0. This is not an officially supported Google product.

Frequently asked questions

Is elephant-goldfish-model free to use?

elephant-goldfish-model is open source under the Apache-2.0 licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does elephant-goldfish-model do?

Open-source skills for designing and reviewing software with AI agents

What is elephant-goldfish-model written in?

elephant-goldfish-model is primarily written in Python. Its source is publicly available at https://github.com/google/elephant-goldfish-model, and it has 3,510 GitHub stars.