> ## Documentation Index > Fetch the complete documentation index at: https://usefused.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Build agents for production. > Harnest is a production harness for Google ADK and LangGraph agents. export const HarnestProjectExplorer = () => { const entries = [{ "label": "agent.py", "path": "agent.py", "description": "The root agent. Managed ADK and LangGraph projects share this declaration; config.yaml selects the framework.", "code": "from harnest.agent import Agent\nfrom harnest.model import LiteLLMModel\n\n\nroot_agent = Agent(\n name=\"support_agent\",\n history=\"session\",\n model=LiteLLMModel.from_openai_environment(),\n)", "language": "python", "optional": false, "href": "/harnest/build/agents-and-graphs", "example": false }, { "label": "instructions.md", "path": "instructions.md", "description": "The root agent’s instructions. Harnest loads this file for the managed agent.", "code": "You are Support Agent.\n\nAnswer clearly, acknowledge uncertainty, and use discovered tools when they are relevant.", "language": "markdown", "optional": false, "href": "/harnest/build/project-configuration", "example": false }, { "label": "config.yaml", "path": "config.yaml", "description": "Agent, framework, and runtime environment settings. Legacy resource and scaling blocks are ignored and not generated. Add an optional root server section to override local serving defaults. This preview uses ADK; select langgraph for a managed LangGraph project.", "code": "apiVersion: harnest.dev/v1alpha1\nkind: Agent\nmetadata:\n name: support-agent\n displayName: Support Agent\nspec:\n enabled: true\n entrypoint: agent:root_agent\n framework:\n name: adk\n mode: managed\n runtime:\n version: \"3.12\"\n dependencyFile: pyproject.toml\n # Configure your compatible endpoint and model before live calls.\n environment:\n OPENAI_MODEL: your-model\n OPENAI_BASE_URL: https://models.example.invalid/v1\n OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT: NO_CONTENT\n ADK_CAPTURE_MESSAGE_CONTENT_IN_SPANS: \"false\"", "language": "yaml", "optional": false, "href": "/harnest/build/project-configuration", "example": false }, { "label": "agent-card.yaml", "path": "agent-card.yaml", "description": "Public identity, capabilities, and the A2A interfaces the agent advertises.", "code": "name: Support Agent\ndescription: A self-contained Harnest agent.\nversion: 0.1.0\nsupportedInterfaces:\n - url: http://127.0.0.1:8080\n protocolBinding: HTTP+JSON\n protocolVersion: \"1.0\"\ncapabilities:\n streaming: true\ndefaultInputModes:\n - text/plain\ndefaultOutputModes:\n - text/plain\nskills:\n - id: respond\n name: Respond\n description: Responds clearly to user requests.\n tags: [assistant]", "language": "yaml", "optional": false, "href": "/harnest/runtime/a2a/serve", "example": false }, { "label": "pyproject.toml", "path": "pyproject.toml", "description": "Your Python dependencies. Harnest supplies the framework; environment sync generates the selected Harnest environment lock.", "code": "[project]\nname = \"support-agent\"\nversion = \"0.1.0\"\nrequires-python = \">=3.12,<3.13\"\ndependencies = []\n\n[dependency-groups]\ndev = [\"pytest>=8,<9\"]\n\n[tool.uv]\npackage = false", "language": "toml", "optional": false, "href": "/harnest/build/project-configuration", "example": false }, { "label": "harnest.lock", "path": "harnest.lock", "description": "The project schema and resolved framework version. Environment sync adds the exact framework pin. Commit this file; schema upgrades preserve that pin.", "code": "apiVersion: harnest.dev/v1alpha1\nkind: ProjectLock\nprojectSchema: 5", "language": "yaml", "optional": false, "href": "/harnest/build/project-configuration", "example": false }, { "label": ".gitignore", "path": ".gitignore", "description": "Keeps generated environments, caches, and local build output out of source control.", "code": ".harnest/\n.venv\n__pycache__/\n.pytest_cache__/", "language": "text", "optional": false, "href": "/harnest/build/project-configuration", "example": false }, { "label": "lib/", "path": "lib/messages.py", "description": "Optional shared Python helpers. Omit this folder until you need reusable code. Import this example with from harnest.lib.messages import normalize.", "code": "def normalize(message: str) -> str:\n \"\"\"Collapse whitespace in a message.\"\"\"\n return \" \".join(message.split())", "language": "python", "optional": true, "href": "/harnest/build/data-models-and-shared-libraries", "example": true }, { "label": "models/", "path": "models/messages.py", "description": "Optional Pydantic contracts. Import this example with from harnest.models.messages import Message.", "code": "from pydantic import BaseModel, Field\n\n\nclass Message(BaseModel):\n \"\"\"Validate a non-empty message.\"\"\"\n\n text: str = Field(min_length=1)", "language": "python", "optional": true, "href": "/harnest/build/data-models-and-shared-libraries", "example": true }, { "label": "tools/", "path": "tools/echo.py", "description": "Optional Agent Tools. Add one public callable per file; its name must match the filename.", "code": "from harnest.agent import tool\n\n\n@tool\ndef echo(message: str) -> str:\n \"\"\"Return a message unchanged.\"\"\"\n return message", "language": "python", "optional": true, "href": "/harnest/build/agent-tools", "example": true }, { "label": "tasks/", "path": "tasks/prepare_report.py", "description": "Optional queued work. Direct calls run inline; deferred execution needs task storage. Tasks are not automatically exposed as Agent Tools.", "code": "from harnest.task import task\n\n\n@task(queue=\"reports\", max_retries=3)\nasync def prepare_report(subject: str) -> dict[str, str]:\n \"\"\"Prepare a report result without external side effects.\"\"\"\n return {\"subject\": subject, \"status\": \"ready\"}", "language": "python", "optional": true, "href": "/harnest/build/queued-tasks", "example": true }, { "label": "cron/", "path": "cron/daily_report.py", "description": "Optional UTC schedules. This example also needs tasks/prepare_report.py and the task runtime and store.", "code": "from harnest.cron import Cron\nfrom tasks.prepare_report import prepare_report\n\n\n# Use UTC so the schedule does not depend on the host timezone.\ndaily_report = Cron(\n \"0 9 * * 1-5\",\n task=prepare_report,\n arguments={\"subject\": \"daily\"},\n)", "language": "python", "optional": true, "href": "/harnest/build/scheduled-tasks", "example": true }, { "label": "subagents/", "path": "subagents/helper.py", "description": "Optional SubAgents. Reference this flat helper explicitly in your root Graph; use a folder for a SubAgent with its own resources.", "code": "from harnest.agent import Agent\nfrom harnest.model import LiteLLMModel\n\n\nhelper = Agent(\n name=\"helper\",\n model=LiteLLMModel.from_openai_environment(),\n instruction=\"Summarize the request and acknowledge missing information.\",\n)", "language": "python", "optional": true, "href": "/harnest/build/subagents", "example": true }, { "label": "mcp/", "path": "mcp/knowledge.py", "description": "Optional MCP Client connections. Export a client() factory and configure the endpoint in your environment.", "code": "import os\n\nfrom harnest.mcp import MCPClient\n\n\ndef client():\n \"\"\"Read the endpoint when Harnest discovers this client.\"\"\"\n return MCPClient.streamable_http(\n os.environ[\"HARNEST_MCP_URL\"],\n prefix=\"knowledge\",\n )", "language": "python", "optional": true, "href": "/harnest/build/mcp-client", "example": true }, { "label": "lifecycle/", "path": "lifecycle/storage.py", "description": "Included and active: the generated agent uses this provider for session and checkpoint storage. Keep it unless you replace those bindings. Additional lifecycle hooks and factories are optional.", "code": "from harnest import lifecycle\nfrom harnest.store import MemoryStore\n\n\n@lifecycle.storage.sessions\n@lifecycle.storage.checkpoints\ndef state_store():\n \"\"\"Share one lifecycle-owned store without placing it in lib.\"\"\"\n return MemoryStore()", "language": "python", "optional": false, "href": "/harnest/runtime/checkpoints-and-storage", "example": false }, { "label": "extensions/", "path": "extensions/starter_runtime/extension.yaml", "description": "Optional Harnest Extensions package reusable application functionality. Declare extension.yaml, export the singleton from extension.py, and put package-owned hooks in lifecycle/. Agent Plugins live separately in plugins/.", "code": "apiVersion: harnest.dev/v1alpha1\nkind: Extension\nmetadata:\n name: starter_runtime\n version: 0.1.0\nruntime:\n entrypoint: extension:extension\ncapabilities: []", "language": "yaml", "optional": true, "href": "/harnest/build/extensions/create", "example": true }, { "label": "plugins/", "path": "plugins/warehouse/plugin.json", "description": "Agent Plugins 1.0 packages contain plugin.json and optional skills/ and mcp.json components. Harnest discovers them without Python registration. Application lifecycle behavior belongs in lifecycle/ or a Harnest Extension.", "code": "{\n \"$schema\": \"https://agent-plugins.org/schemas/1.0.0/plugin.schema.json\",\n \"name\": \"warehouse\",\n \"version\": \"1.0.0\",\n \"description\": \"Query the shared warehouse\"\n}", "language": "json", "optional": true, "href": "/harnest/build/agent-plugins", "example": true }, { "label": "sandbox/", "path": "sandbox/calculations.py", "description": "Optional execution environments. Assign sandboxes=[\"calculations\"] on an Agent, then call context.sandboxes[\"calculations\"] from an authored tool. This container needs Docker when executed.", "code": "from harnest.extensions.docker import docker\nfrom harnest.sandbox import SandboxNetworkPolicy\n\n\ncalculations = docker.sandbox(\n image=\"python:3.12-slim\",\n network_policy=SandboxNetworkPolicy.none(),\n timeout_seconds=120,\n max_output_bytes=1_048_576,\n)", "language": "python", "optional": true, "href": "/harnest/build/sandboxing", "example": true }, { "label": "skills/", "path": "skills/getting-started/SKILL.md", "description": "Optional Agent Skills. Each skill lives in its own directory with a SKILL.md instruction file.", "code": "---\nname: getting-started\ndescription: Apply the agent's core instructions when answering a general request that does not require a more specialized skill.\n---\n\n# Getting started\n\n1. Identify the user's requested outcome before acting.\n2. Use a discovered tool only when it materially helps produce that outcome.\n3. State uncertainty plainly and never invent tool results or external facts.\n4. Return a concise answer with the most useful result first.", "language": "markdown", "optional": true, "href": "/harnest/build/agent-skills", "example": true }, { "label": "evals/", "path": "evals/starter.evalset.json", "description": "Optional evaluation datasets. Add these when you want to check agent responses against expected outcomes.", "code": "{\n \"eval_set_id\": \"starter\",\n \"name\": \"Starter evaluation\",\n \"eval_cases\": [\n {\n \"evalId\": \"answers_greeting\",\n \"conversation\": [\n {\n \"userContent\": {\"role\": \"user\", \"parts\": [{\"text\": \"Say hello briefly.\"}]},\n \"finalResponse\": {\"role\": \"model\", \"parts\": [{\"text\": \"Hello!\"}]}\n }\n ],\n \"sessionInput\": {\"appName\": \"support_agent\", \"userId\": \"eval-user\", \"state\": {}}\n }\n ]\n}", "language": "json", "optional": true, "href": "/harnest/build/evaluations", "example": true }, { "label": "tests/", "path": "tests/unit/test_agent.py", "description": "Optional authored tests. Put offline checks in tests/unit/ and opt-in live checks in tests/smoke/. The default scaffold creates a guide in each folder.", "code": "def test_agent_name(agent):\n \"\"\"Check the generated agent’s public name without a model call.\"\"\"\n assert agent.name == \"support_agent\"", "language": "python", "optional": true, "href": "/harnest/build/testing-and-compilation", "example": true }]; const [selectedIndex, setSelectedIndex] = useState(0); const selected = entries[selectedIndex]; const selectEntry = event => { setSelectedIndex(Number(event.currentTarget.value)); }; return
support-agent/
{selected.path}

{selected.description}

{} {selected.example &&

Example · this folder contains only _README.md guides by default.

} Read the guide →
{selected.code}
; }; [Build your first agent →](/docs/harnest/get-started/install) ## Explore a Harnest project Select a file or folder to explore the code behind a Harnest agent. ## Focus on what your agent does Whether you’re building a support assistant, an internal knowledge tool, or an operations workflow, Harnest gives you a place for each part of the application. | What you need | What Harnest provides | | -------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------- | | Connect to your business | [Agent Tools](/docs/harnest/build/agent-tools) and [MCP Client](/docs/harnest/build/mcp-client) connections for your APIs and services | | Reuse expertise | [Agent Skills](/docs/harnest/build/agent-skills), [SubAgents](/docs/harnest/build/subagents), and [Agent Plugins](/docs/harnest/build/agent-plugins) | | Share application capabilities across agents | [Harnest Extensions](/docs/harnest/build/extensions) package reusable functionality and lifecycle integrations | | Check behavior before shipping | Tests, evaluations, and a local playground | | Run beyond a single request | Session storage, checkpoints, approvals, and durable task capabilities | | Fit your production environment | Authentication hooks, telemetry, compiled artifacts, and a serving API | Start with the capabilities you need. Configure persistent services, authentication, and deployment as you move toward production. The [production guide](/docs/harnest/runtime/serving/production) covers that next step. ## Start with code or Studio Install Harnest on macOS or Linux. No preinstalled Python is required. ```bash theme={null} curl -fsSL \ https://raw.githubusercontent.com/Usefused/harnest/main/install.sh | sh ``` See [installation options](/docs/harnest/get-started/install), or create your first project: ```bash theme={null} harnest init support-agent --framework adk cd support-agent ``` Use `--framework langgraph` if you prefer LangGraph. [Configure your model](/docs/harnest/build/models-and-libraries/configure-a-model), edit `instructions.md`, then test and serve: ```bash theme={null} harnest test . harnest serve . --reload ``` Open the playground at `http://127.0.0.1:1907/` to try it. Prefer a visual workspace? Launch [Harnest Studio](/docs/harnest/build/testing-and-compilation#review-changes-in-agent-builder) with `harnest studio --workspace /path/to/agents`. Already have an agent? [Bring it into Harnest](/docs/harnest/get-started/migrate) in advanced mode to keep direct framework control, then adopt managed capabilities at your own pace. **[Build your first agent →](/docs/harnest/get-started/install)** Harnest is open source under Apache 2.0, built and maintained by [Fused](https://usefused.com).