JetBrains has announced the launch of the "Eco Mode" operating setting in its agent-based AI software assistance tool, "Junie." This new system aims to restructure how AI models consume resources during long programming tasks, contributing to a significant reduction in operational costs without affecting the efficiency of solving programming problems.
AI agents typically rely on executing tasks through small, sequential steps: opening files, searching the project, making edits, and testing code repeatedly. Usually, a single, expensive AI model is run throughout this entire process. The new Eco Mode addresses this issue by splitting the work between an intelligent, expensive primary model that is limited to planning, and another, less expensive model that handles practical execution tasks.
How Eco Mode Works
The new system operates through two fundamental stages to distribute roles efficiently based on the nature of the required task:
- Planning Phase (Architectural Role): The model chosen by the user (such as Opus, Fable, Grok, or GPT) studies and searches the code without making any actual edits, except for potentially writing a small test to prove a bug if an error is reported. This model's role is limited to exploring the problem and creating a detailed plan that includes the goal, scope, location of the edit, methodology, testing methods, and potential risks.
- Execution Phase (Builder Role): The tool transfers the conversation and the complete action plan to another, less expensive model (currently GPT-6 Luna). This model handles the long practical steps such as editing files, running builds, testing code, and fixing errors until the task is successfully completed.
Why This Development Matters to Developers
Internal tests conducted by the company on two different benchmarks showed a significant decrease in model cost per task; savings reached approximately 57% in the second benchmark and 48% in the first, while success and problem-solving rates remained stable with a change not exceeding one percentage point compared to the traditional method.
Availability and Supported Versions
Eco Mode is currently available to Early Access Program (EAP) users for the JetBrains Air development environment in specific versions including IntelliJ IDEA 2026.3 Beta, with other development environments to follow in their beta versions, in addition to stable versions 2026.2. The feature is also available by default in the Junie CLI command interface starting from version 26.10.20 for supported configurations.