A Unified Open-Source Agent SDK Behind Every Cline Surface
Cline has introduced @cline/sdk, an open-source agent runtime that now powers its CLI, Kanban interface, and upcoming VS Code and JetBrains extensions. Instead of extending a codebase tightly coupled to specific IDEs, the team rebuilt the core agent loop as a standalone, portable SDK. This coding agent runtime is designed to be installed via npm and reused across interfaces, so product surfaces no longer own their own agent logic—they simply connect to a shared foundation. For development teams, this marks a shift from consuming a single packaged tool to adopting an extensible open-source agent SDK they can inspect, fork, or embed directly. By publishing the same runtime it uses internally, Cline is effectively turning its own infrastructure into a public building block for Cline SDK development, lowering the barrier for organizations that want to experiment with custom coding agents without starting from scratch.
Layered TypeScript Stack Separates Concerns and Avoids Vendor Lock-In
At the heart of the SDK is a layered TypeScript architecture with clear single-responsibility boundaries. The @cline/shared package holds core types and utilities, while @cline/llms manages the provider layer, supporting Anthropic, OpenAI, Google, AWS Bedrock, Mistral, LiteLLM, and any OpenAI-compatible endpoint. Crucially, this provider logic lives outside the agent loop, so switching models is a configuration change rather than a code refactor. Above the stateless @cline/agents loop, which handles iterations, tools, and events, @cline/core orchestrates stateful behavior such as session lifecycle, persistence, and configuration discovery. This separation allows teams to adopt just the pieces they need or install the full open-source agent SDK as @cline/sdk. In practice, it encourages experimentation with multiple model vendors while avoiding hard wiring any single provider into the core coding agent runtime, reinforcing flexibility over lock-in.
From Persistent Sessions to Teams of Agents: New Capabilities on a Shared Runtime
Rebuilding around a portable SDK has changed what Cline can do for long-running, complex work. Sessions no longer disappear when a UI restarts and can move between the CLI, Kanban, and editor extensions while retaining context. The stateless agent loop remains reusable, while the enclosing runtime becomes durable, enabling features such as checkpointing and scheduled CRON jobs. Performance benchmarks reflect these improvements: on Terminal Bench 2.0, Cline CLI running claude-opus-4.7 reaches 74.2%, compared with 69.4% for Claude Code on the same model, while kimi-k2.6 hits 55.1% versus OpenCode’s 37.1% on the same run. Native support for agent teams and subagents lets a session delegate work to specialists, coordinate progress, and exchange handoff notes without requiring an external orchestrator. Plugins further extend the SDK, allowing teams to add domain-specific tools, lifecycle hooks, rules, and connectors, including web search and MCP integrations.
Local-First Runtime in a World of Cloud Workspaces
Many emerging coding agents are built around cloud-based, persistent workspaces that keep code and sessions in managed environments. Cline’s SDK pushes in a different direction: a local-first coding agent runtime that can be wired into terminals, editors, and CI systems while remaining under the developer’s control. With Cline CLI 2.0 emphasizing terminal-first execution and headless CI, and Cline Kanban orchestrating multiple agents across a git repository, the SDK becomes the shared backbone rather than a remote black box. Experimental connector channels in the CLI allow agents to surface into platforms like Telegram, WhatsApp, and Slack using a simple setup wizard, but the core execution still lives wherever the team chooses to run it. For organizations wary of routing all development activity through hosted tools, this model offers a path to build custom coding agents that integrate into existing workflows without ceding control to a centralized workspace provider.
Democratizing Agent Tooling for the Next Wave of Developer Productivity
By shipping the runtime that powers its own products as @cline/sdk, Cline is turning a once-internal infrastructure move into a catalyst for broader Cline SDK development. Teams can compose their own custom coding agents on top of a battle-tested open-source agent SDK, mixing in plugins, model providers, and connectors as needed. Because the agent loop is stateless and model-agnostic, and because IDEs simply sit on top of the runtime instead of owning it, developers avoid getting locked into a single editor, model vendor, or orchestration layer. For the more than 7 million developers already using Cline’s tools, this unlocks a continuum: start with CLI or Kanban, then progressively adopt the SDK to tailor behavior to a team, project, or organization. As agentic coding matures, this kind of open, portable runtime may become a reference pattern for how developer-first agents are built and shared.