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Google’s open-source blog dated October 22, 2026 introduced the Elephant-Goldfish Model (EGM) plugin: a Spec-Driven Development flow for AI coding agents. The repository is google/elephant-goldfish-model, licensed Apache 2.0. The README ends with a clear line: This is not an officially supported Google product. So this note is about an open method and plugin—not a Google-hosted product with a formal support SLA.
Elephant drafts; Goldfish reviews
EGM splits the work across two kinds of sessions:
- Elephant — a deep-context session that keeps project background, discussion, and micro-decisions. It brainstorms and drafts a living design document (problem, plan, alternatives, files to change). The blog’s framing: no code in this session—design and intent first.
- Goldfish — isolated, zero-context subagents that read only the draft specification and live source. They do not share the designer’s chat memory, so they are meant to catch gaps the drafting session already “agreed with itself” on.
The plugin’s review path (README Skills / blog “Goldfish Protocol”) walks a multi-stage check in plain terms: can a fresh reader restate the plan; do antagonistic reviewers find edge cases and missing dependencies; is the spec ready to implement (paths, structures, signatures clear enough). Commands in the README include /egm-brainstorm, /egm-draft, /egm-review, plus resolve / drift / bootstrap helpers. In Claude Code, the prefix is /egm:….
The point of the split is familiar whenever one long chat keeps saying “looks good” after rewriting the same design three times: review the design before writing code, with a session that was not in the drafting conversation.
Which harnesses the README lists
| Harness | Install (README wording, shortened) |
|---|---|
| Any AI agent | Ask the agent to install the google/elephant-goldfish-model repo |
| Antigravity | agy plugin install + the google/elephant-goldfish-model repo URL (or /plugin in the IDE) |
| Claude Code | marketplace add google/elephant-goldfish-model, then install egm@egm |
| Codex | marketplace add, then codex plugin add egm@egm |
| Claude Cowork / ChatGPT | See the repo’s harness docs for desktop / workspace setup |
That table is how to wire the plugin into an existing coding harness—not a claim that Google shipped a new consumer coding product on each of those platforms. For how Claude Code and Codex compare at the $20 tier, see Claude Code vs Codex: What $20 Gets You and Which to Pick. For what changing the coding harness itself can do to pass rate and bill, see Same Model, Different Coding Harness: Pass Rate Barely Moves, the Bill Does. Another multi-agent scale axis (same Copilot loop, more workers) is in Same Copilot Loop, More Agents: Agensh Claims Pass Rates Rise Toward 1,024 Workers.
What the README makes clear
- Not an official Google product. The README says so; treat EGM as an open method and plugin, not a supported hosted service.
- Open source ≠ free model calls. The plugin orchestrates sessions; tokens still bill through the model / harness already in use.
- No promised bug counts. The blog hopes the flow helps produce the intended code on the first pass; that is an author goal, not a measured guarantee on this site.
For how ordinary prompting versus an independent review flow differs on missed requirements, rework, and token cost, that comparison has not been run here yet. Feedback can go through the site-owner contact link in the footer. For reference only.
Not Baseten’s Elephant
The name “Elephant” also appears in an earlier note on Baseten Mammoth-1 and Elephant-1—decision models with a time-limited free window on Vercel. That is a different product line and a different story. See Baseten Mammoth-1 and Elephant-1 Are Free on Vercel Through October 27. This EGM piece is Google’s design-chat / design-review plugin, not those models.