spec-driven-development

Google has open-sourced the Elephant-Goldfish Model (EGM) plugin under Apache 2.0, requiring coding agents to draft and defend a design spec before writing code. The core idea is context splitting: a long-lived "Elephant" session holds project history and drafts the design doc, while fresh "Goldfish" subagents read only that doc and referenced files, avoiding inherited blind spots. The review runs five stages; in Google's tests Codex 0.163.0 and Antigravity CLI completed 15-16 reviewers end to end, though reviews consume the user's own model quota and issue #237 reports AGENTS.md leaking into some CLI reviewers.