> ## Documentation Index
> Fetch the complete documentation index at: https://docs.usefused.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Lifecycle

> Add application resources, invocation hooks, output policy, and native integrations.

Lifecycle extensions manage behavior around the agent without turning that behavior into tools.

| Need                                | Use                  |
| ----------------------------------- | -------------------- |
| Start and close a dependency        | Application resource |
| Publish a value to agent code       | Context resource     |
| Observe or transform execution      | Invocation hook      |
| Control public SubAgent narration   | Output policy        |
| Add framework-specific behavior     | Native integration   |
| Add application HTTP routes         | HTTP route factory   |
| Store sessions or checkpoints       | Storage factory      |
| Store session-owned media           | Asset store          |
| Authenticate or resolve credentials | Security factory     |
| Export traces or logs               | Telemetry exporter   |

Lifecycle is root-owned. SubAgents cannot add private lifecycle extensions.

<CardGroup cols={2}>
  <Card title="Application resources" icon="boxes-stacked" href="/harnest/runtime/lifecycle/application-resources">
    Start, publish, share, and close application dependencies.
  </Card>

  <Card title="Invocation hooks" icon="arrows-rotate" href="/harnest/runtime/lifecycle/invocation-hooks">
    Observe or transform agent, model, and tool execution.
  </Card>

  <Card title="Output policy" icon="message" href="/harnest/runtime/lifecycle/output-policy">
    Decide whether intermediate SubAgent narration becomes public.
  </Card>

  <Card title="Native integrations" icon="code" href="/harnest/runtime/lifecycle/native-integrations">
    Add ADK plugins or LangGraph middleware when portable hooks are not enough.
  </Card>
</CardGroup>

## Related runtime boundaries

| Boundary                              | Page                                                                                     |
| ------------------------------------- | ---------------------------------------------------------------------------------------- |
| Sessions and checkpoints              | [Checkpoints and storage](/harnest/runtime/checkpoints-and-storage)                      |
| Caller identity and downstream tokens | [Authentication and credentials](/harnest/runtime/authentication-and-credentials)        |
| Logs, traces, and audit events        | [Telemetry](/harnest/runtime/telemetry)                                                  |
| Application-specific HTTP contracts   | [Custom HTTP endpoints](/harnest/runtime/custom-http-endpoints)                          |
| Typed media input and output          | [Accept multimodal data](/harnest/build/models-and-libraries/typed-multimodal-contracts) |
| Decorator signatures and cardinality  | [Runtime extension reference](/harnest/reference/runtime-extensions)                     |