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

# Introduction

> A cloud-native harness for long-running agents.

Cerca is a hosted runtime for agents that need to keep working past a single prompt. Instead of running a harness on your own VM — owning the patches, restarts, recovery semantics, and sandbox — you configure agents over an API and the runtime keeps them executing through model errors, tool failures, and process restarts.

Every agent and thread is durable and addressable, so long-running work picks up where it left off through restarts and partial failures.

## What the runtime gives you

* **Durable execution and context management.** Threads recover from transient errors — bad LLM responses, timed-out tool calls, dropped connections — without losing state. Old turns are compacted and sub-agents spun up so threads stay responsive as they grow.
* **A cloud sandbox.** Each agent has a CLI environment to write and run code in.
* **Secure credentials.** Connections (OAuth or API keys) are stored encrypted; tools call through them, so the model never sees raw secrets.
* **Approvals.** Tools can be marked approval-required. The runtime pauses on those calls until a decision is recorded.
* **Memory.** Agents can write and search structured memory across threads.

## What you provide

* **Custom tools** — HTTP endpoints or MCP servers the agent can call.
* **Goals and instructions** — system prompt, default model, and standing context the agent can rely on.
* **Approval policies** — which tools run autonomously and which need a human.
* **Inbound events** — webhooks or schedules that wake an agent up.

## Core objects

* **Agent** — a durable workspace, usually one per end-user. Holds configuration, memory, connections, and any threads it has run.
* **Thread** — one conversation or run inside an agent. Threads stream events, can pause for approvals, and can spawn sub-threads.
* **Fleet** — shared configuration for a group of agents: tools, OAuth apps, default instructions, approval defaults. Configure tools once at the fleet level instead of per agent.

## Next steps

* [Quickstart](/quickstart) — verify your API key, create an agent, start a thread.
* [Client libraries](/client-libraries) — install the TypeScript, Python, Go, Ruby, or CLI client.
* [Authentication](/authentication) — API keys, connections, and credential scoping.
* [Agents](/concepts/agents), [threads](/concepts/threads), [tools](/concepts/tools), [approvals](/concepts/approvals), and [webhooks](/concepts/webhooks) for the mental model.
* API Reference — exact request shapes and response schemas.