Is Gemini CLI Still Open Source — Reading the Apache 2.0 Code and the Backend Terms as Two Layers, and the Adoption Risk After the Antigravity CLI Transition

Google announced the transition from Gemini CLI to the closed-source Antigravity CLI and cut off free, individual access on 2026-06-18. Yet the Gemini CLI code itself stays Apache 2.0 and the repository keeps shipping releases. Whether to adopt it becomes clear once you read it as two layers: the code license and the backend service terms. This article lays out what happened, the irrevocability of Apache 2.0, the mutability of the service terms, the governance reality, the technical incompatibilities of migration, and the alternatives and defenses, as of 2026.