{"slug": "building-an-agent-with-the-cline-sdk", "title": "Building an Agent with the Cline SDK", "summary": "Cline released an open-source TypeScript SDK for embedding its agent runtime into custom scripts, products, and CI workflows. The SDK allows developers to build focused agentic applications, such as a release notes generator that inspects recent git history and produces markdown output. This launch separates Cline's agent runtime from its VS Code extension, making it reusable across different interfaces and tools.", "body_md": "# Building an Agent with the Cline SDK\n\n### In this article, we will build a small release notes generator that uses the Cline SDK to inspect recent git history and turn it into readable markdown.\n\n[Cline](https://cline.gg/alex) is an open-source AI coding agent focused on real software work. Most developers first encounter Cline as an assistant in the editor or terminal, but Cline is broader than a single interface.\n\nIt has both a **CLI** and an **SDK**:\n\nThe\n\n**CLI** is for running agent workflows directly from the terminalThe\n\n**SDK** is for embedding the same agent runtime inside your own scripts, products, CI jobs, and internal tools\n\nThat distinction matters. In the [Cline SDK launch post](https://cline.bot/blog/introducing-cline-sdk-the-upgraded-agent-runtime), the team explains that the original product started inside the VS Code extension, and over time the runtime became harder to separate from the IDE around it. The SDK is the answer to that problem: the agent runtime is treated as a shared service rather than an implementation detail hidden inside one app.\n\nThat is also why the SDK is more interesting than a thin API wrapper, the same runtime now powers Cline across the CLI and IDE surfaces, while staying open for other teams to embed in their own products. The low-level agent loop stays reusable, and the stateful runtime around it becomes more durable, portable, and product-agnostic.\n\nThe SDK documentation describes Cline SDK as an open-source **TypeScript** framework for building agentic applications. The launch post adds a few more important ideas:\n\nCline 2.0 is built as a layered TypeScript stack\n\nteams can start with a small surface area and add more runtime pieces later\n\nthe runtime is extensible through tools, plugins, MCP servers, skills, and hooks\n\nprovider choice is not locked to one model vendor\n\nThat makes TypeScript the natural choice for a first project.\n\nIn this article, we will build a small release notes generator that uses the Cline SDK to inspect recent git history and turn it into readable markdown.\n\n## Why the Cline SDK is a good fit here\n\nThis release-notes project is small, but it matches the SDK well because it uses the part of Cline that matters most: the runtime for tool-using agents.\n\nWe are not trying to rebuild the whole Cline product. We are only borrowing the runtime shape:\n\ndefine a focused tool\n\ngive that tool to an agent\n\nlet the agent inspect real project state\n\nturn the result into a useful artifact\n\nThat pattern lines up closely with how the Cline team positions the SDK in the launch post: something you can embed in scripts, internal tools, CI workflows, and other product surfaces, not just in an IDE.\n\n## What we are building\n\nThe project exposes one command:\n\n```\nnpm run draft-release -- --since 20\n```\n\nIt does one job well:\n\nstart a Cline agent\n\ngive the agent one custom tool,\n\n`get_recent_commits`\n\nlet the tool read recent git history from the current repository\n\nhave the agent turn that data into release notes\n\nprint the result to stdout\n\nThe interesting part is not the CLI itself. The interesting part is the architecture: our application provides a narrow, useful capability, and the Cline runtime decides how to use it.\n\nThat is exactly the kind of problem the SDK is meant for. As the launch post puts it, the runtime is no longer supposed to live only inside one UI surface. It is something you can pull into your own stack.\n\n## Project structure\n\n```\ncline-demo/\n├── .env.example\n├── package.json\n├── tsconfig.json\n└── src/\n    ├── git.ts\n    ├── index.ts\n    └── prompt.ts\n```\n\n## Setup\n\nThe Cline SDK requires **Node.js 22+**.\n\nInstall dependencies:\n\n```\ncd cline-demo\nnpm install\n```\n\nCreate your environment file:\n\n```\ncp .env.example .env\n```\n\nThen fill in your OpenAI key:\n\n```\nOPENAI_API_KEY=your_openai_api_key_here\nOPENAI_MODEL=gpt-4.1-mini\n```\n\nThis project uses Cline’s `openai-native`\n\nprovider.\n\nRun it from inside any git repository:\n\n```\nnpm run draft-release -- --since 20\n```\n\n## How the code works\n\n`src/index.ts`\n\nThis is the entry point. It does three things:\n\nparses the\n\n`--since`\n\nargumentcreates the custom\n\n`get_recent_commits`\n\ntoolruns a Cline\n\n`Agent`\n\nand prints the final result\n\nThe core shape is intentionally small:\n\n``` js\nconst agent = new Agent({\n  providerId: \"openai-native\",\n  modelId: process.env.OPENAI_MODEL ?? \"gpt-4.1-mini\",\n  apiKey,\n  systemPrompt: buildSystemPrompt(),\n  tools: [createRecentCommitsTool()],\n  maxIterations: 6,\n})\n\nconst result = await agent.run(buildUserPrompt(parseSince(process.argv.slice(2))))\nprocess.stdout.write(`${result.outputText.trim()}\\n`)\n```\n\nThis is the mental model to remember: **your app defines tools, and Cline supplies the agent runtime**.\n\nIn other words, we are not reimplementing agent orchestration ourselves. We are reusing the same idea Cline uses internally: a runtime that can reason, call tools, and produce a final artifact.\n\n`src/git.ts`\n\nThis file keeps the repository access logic out of the main program.\n\nIt uses:\n\n`git log`\n\nto collect recent commits`git show --name-only`\n\nto collect changed file paths per commit\n\nEach commit is returned as structured data:\n\nsha\n\nshortSha\n\nauthor\n\ndate\n\nsubject\n\nbody\n\nfiles\n\nThat structure matters. It gives the model enough context to infer whether a change is a feature, a fix, a maintenance task, or something that may require an upgrade note.\n\n`src/prompt.ts`\n\nThis file contains the prompt contract.\n\nThe system prompt tells the agent to:\n\ncall\n\n`get_recent_commits`\n\nbefore answeringuse only tool evidence\n\nreturn markdown only\n\norganize the answer into:\n\nOverview\n\nFeatures\n\nFixes\n\nDocs / Chore\n\nUpgrade Notes\n\nKeeping the prompt separate makes the project easier to explain and modify. The runtime code stays small, while the output rules live in one place.\n\n## The custom tool\n\nThe single most important part of the project is the tool definition:\n\n```\nfunction createRecentCommitsTool() {\n  return createTool({\n    name: \"get_recent_commits\",\n    description:\n      \"Read recent git commits from the current repository, including commit subjects, bodies, authors, dates, and changed file paths.\",\n    inputSchema: {\n      type: \"object\",\n      properties: {\n        since: { type: \"number\", description: \"How many recent commits to inspect.\" },\n      },\n      required: [\"since\"],\n      additionalProperties: false,\n    },\n    execute(input, context) {\n      context.emitUpdate?.(`Reading last ${input.since} commits from git`)\n      return getRecentCommits(process.cwd(), input.since)\n    },\n  })\n}\n```\n\nWithout this tool, the agent would only be rephrasing whatever text we pasted into the prompt. With the tool, it can actively inspect the repository through a controlled interface.\n\nThat is where the SDK becomes interesting: it is not just a text wrapper around a model. It is a runtime for tool-using agents.\n\nAnd if this project needed to grow later, the SDK already has room for that. The Cline team highlights plugins, custom tools, MCP integration, skills, and multi-agent capabilities as extension points. We are deliberately not using all of that here, but it is useful to know that the simple version and the more advanced version can live on the same foundation.\n\n## Why release notes are a good SDK use case\n\nRelease notes sit in a sweet spot for agent automation:\n\nthe input is messy but structured enough to inspect\n\nthe output has a clear shape\n\nthe task is useful in real projects\n\nthe problem is narrow enough to understand quickly\n\nIn other words, this is not a toy chatbot, but it is also not an overbuilt autonomous system. It is a believable piece of SDLC automation.\n\n## Example output\n\nHere is the kind of markdown the tool produces:\n\n```\n# Release Notes\n\n## Overview\nThis release focused on improving authentication flows, tightening API validation, and cleaning up project documentation.\n\n## Features\n- Added a token refresh path for expired sessions.\n- Introduced a reusable API client helper for authenticated requests.\n\n## Fixes\n- Fixed inconsistent validation errors in the user settings endpoint.\n- Resolved a bug where logout did not fully clear local session state.\n\n## Docs / Chore\n- Updated onboarding docs for local development.\n- Refactored auth-related file organization for easier maintenance.\n\n## Upgrade Notes\n- If you rely on the old auth client helper, update imports to the new shared client module.\n```\n\n## Final takeaway\n\nThe CLI version of Cline is about **using** an agent from the terminal. The SDK version is about **embedding** that agent into your own software.\n\nThat is the main idea behind the Cline SDK launch as well: pull the runtime out of a single product surface, make it reusable, and let other developers build on top of it.\n\nThis project shows that idea in a compact form:\n\ndefine one useful tool\n\nhand it to a Cline agent\n\nlet the agent inspect real project data\n\nturn the result into a polished artifact\n\nOnce this pattern clicks, the same structure can be reused for PR summaries, changelog drafting, test-plan generation, issue triage, and other software delivery workflows.", "url": "https://wpnews.pro/news/building-an-agent-with-the-cline-sdk", "canonical_source": "https://packagemain.tech/p/building-an-agent-with-the-cline-sdk", "published_at": "2026-05-30 11:44:17+00:00", "updated_at": "2026-05-30 11:54:12.906701+00:00", "lang": "en", "topics": ["ai-agents", "ai-tools", "ai-products", "ai-infrastructure", "ai-startups"], "entities": ["Cline", "Cline SDK", "Cline CLI", "VS Code", "TypeScript", "Cline.gg", "Cline.bot"], "alternates": {"html": "https://wpnews.pro/news/building-an-agent-with-the-cline-sdk", "markdown": "https://wpnews.pro/news/building-an-agent-with-the-cline-sdk.md", "text": "https://wpnews.pro/news/building-an-agent-with-the-cline-sdk.txt", "jsonld": "https://wpnews.pro/news/building-an-agent-with-the-cline-sdk.jsonld"}}