Overview
Cline is an AI coding agent that started as a pioneering VS Code extension for agentic development. It now offers an upgraded, modular runtime SDK (@cline/sdk) that powers Cline across VS Code, JetBrains, and the CLI. The core agent harness has been rebuilt into a pluggable, product-agnostic runtime, making it durable, portable, and reusable. Users can install the SDK via npm i -g @cline/sdk and build custom agents on top of it.
Application scenarios
Agentic coding in IDEs
Use Cline within VS Code, JetBrains, or the CLI to automate complex coding tasks.
Long-running agent workflows
Sessions persist across UI restarts, so long-running tasks don't die when the editor restarts.
Multi-agent teams
The runtime supports subagents and multi-agent collaboration for larger projects.
Terminal-based automation
The CLI version can execute terminal commands and handle benchmarks with frontier models.
Custom tool development
Teams can build and surface custom tools via the SDK’s pluggable architecture.
Cross-surface agent sessions
Move an agent session from VS Code to CLI without losing state.
Core features
Modular agent SDK
The core runtime is abstracted into a pluggable SDK (`@cline/sdk`) that any team can install and extend.
Durable runtime
Long-running agent work no longer dies with a UI restart; sessions can move across surfaces.
Stateless agent loop
The low-level agent loop stays stateless and reusable, while the runtime around it becomes durable and product-agnostic.
Improved agent harness
Rewritten prompts, simplified loop, tighter context management, better feedback loops, and improved error handling.
Terminal Benchmark support
Cline CLI achieves competitive pass@1 scores on terminal-bench 2.0 for both frontier and open-weight models.
Cross-IDE compatibility
The SDK powers Cline across VS Code, JetBrains, and CLI, not just a single editor.
Open-source foundation
The SDK is open-sourced so any team can build on it, including the Cline team themselves.
Modular agent SDK The core runtime is abstracted into a pluggable SDK (`@cline/s
Modular agent SDK The core runtime is abstracted into a pluggable SDK (`@cline/sdk`) that any team can install and extend.
Target users
Cline is built for developers and engineering teams who want a modular, extensible agent runtime for AI-powered coding. It suits individual developers using VS Code or JetBrains, as well as teams building custom agentic workflows, multi-agent systems, or long-running automation tasks. The open-source SDK also targets tool builders and platform engineers who need a pluggable agent harness.
How to use
Install the SDK globally via npm: npm i -g @cline/sdk . Then use it within VS Code, JetBrains, or the CLI to start agentic coding sessions. For custom agents, extend the pluggable runtime by adding your own tools and surfaces. The SDK is open-source, so you can also fork or embed it into your own products.
Effect review
Cline’s shift from a VS Code extension to a modular SDK is a pragmatic move that addresses the pain of maintaining a monolithic agent runtime. The Terminal Benchmark results show it competes well with other CLI agents like Codex and Claude Code across both frontier and open-weight models. The durability and cross-surface portability are genuine improvements for teams running long agent sessions. While the SDK is still new, the open-source approach and clear architectural separation make it a solid foundation for building next-generation AI coding agents.
Frequently asked questions
What is Cline?
Cline is an AI coding agent that started as a VS Code extension for agentic development and now offers a modular runtime SDK for building extensible, next-generation AI tools.
Is Cline free to use?
Cline offers both free and paid tiers; the VS Code extension is free, while the SDK may have usage-based pricing or licensing options.
What can I build with Cline's SDK?
You can build extensible AI-powered coding agents, automated development workflows, and custom tools that integrate with various IDEs and platforms.
Does Cline work with other IDEs besides VS Code?
While Cline started as a VS Code extension, its modular SDK is designed to be IDE-agnostic, allowing integration with other editors and environments.
How does Cline differ from other AI coding agents?
Cline focuses on modularity and extensibility, providing a runtime SDK that allows developers to customize and extend its capabilities beyond typical agentic features.
Can I contribute to Cline's development?
Yes, Cline is open-source, and contributions are welcome via its GitHub repository, where you can report issues, suggest features, or submit code.
Launch URL
https://cline.bot/blog/introducing-cline-sdk-the-upgraded-agent-runtimeTags
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