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

# Durable Agent (Local)

> Test local-runtime durability with a single agent process — kill mid-stream and reconnect from a saved offset, no server required

The **`durable_agent/local`** example is an interactive **zero-infrastructure lab**. The in-process runtime is durable by default via [durable-go](https://github.com/agenticenv/durable-go) — no server, no worker, no client/worker split. Kill the agent mid-stream, restart it from the same working directory, and reconnect with `GetAgentStream` (no `WithOffset` — local's stream only supports `fromOffset` 0; reconnect replays step history from the start).

Use it after [In-Process runtime](/runtimes/in-process) when you need to **feel** durable-by-default in action, with nothing to install. For the split worker/agent Temporal lab, see [Durable Agent (Temporal)](/examples/durable-agent); for the single-process Restate lab, see [Durable Agent (Restate)](/examples/durable-agent-restate).

Source: [`examples/durable_agent/local/`](https://github.com/agenticenv/agent-sdk-go/tree/main/examples/durable_agent/local)

<Note>
  Step-by-step exercises: **[`examples/durable_agent/local/README.md`](https://github.com/agenticenv/agent-sdk-go/blob/main/examples/durable_agent/local/README.md)**.
</Note>

## Architecture

| Process | Entry | SDK pattern |
| - | - | - |
| **Agent** | `durable_agent/local` | `NewAgent` — durable by default, no `WithLocalConfig` needed |

Everything runs in one process. The durable-go journal (`./agent_data/local-durable-agent`) on local disk *is* the durability mechanism — there is no separate server to keep running between kill and restart.

Streaming and reconnect use the same public `GetAgentStream` / `GetAgentRun` APIs as Temporal/Restate, minus `WithOffset(n>0)`: reconnect always replays already-completed steps as one coalesced message each, not the original token-by-token stream, and is not seekable to an arbitrary position (see [Durable Execution](/advanced/durable-execution)).

State file: `/tmp/durable_agent_local_runstate.json`.

## Before you start

From **`examples/`**, after [Configuration](/examples/configuration) (just an LLM provider key — no runtime env vars needed):

```bash theme={null}
go run ./durable_agent/local
```

No `task infra:*` step, no server to start.

## Durability scenarios

| Scenario | What to try | What you learn |
| - | - | - |
| **1. Happy path** | REPL + short prompt | End-to-end local durable stream |
| **2. Kill mid-stream** | `pkill -SIGKILL` during a long prompt; restart from the same directory; answer `y` to reconnect | `GetAgentStream` resumes a genuinely live run (no `WithOffset`) |
| **3. Graceful Ctrl+C** | Ctrl+C during a long prompt; restart; answer `y` to reconnect | **Not** the same as a crash — `a.Close()` cancels the in-flight run; reconnect gets `ErrRunAlreadyCompleted` instead of resuming |
| **4. Already finished** | Reconnect once to let it finish, then replay a stale saved state | `ErrRunAlreadyCompleted` via the more obvious path — local has no server to finish an abandoned run for you, so you must reconnect once first |
| **5. `DURABILITY=off`** | Start with `DURABILITY=off`, kill mid-stream, restart | `ErrStreamNotFound` — no journal existed for that run; this is what durable-by-default saves you from |

Full steps: [README](https://github.com/agenticenv/agent-sdk-go/blob/main/examples/durable_agent/local/README.md). Protocol details: [Durable Execution](/advanced/durable-execution).

## Production engine

The lab uses the SDK-built engine (plaintext journal). For payload codec, journal MAC, or a step-token key that survives restart, pass a caller-owned `durable.Engine` as `local.LocalConfig.Engine` — you own `Close`. Runnable example: [Durable Engine](/examples/durable-engine). Snippet: [README — Production engine](https://github.com/agenticenv/agent-sdk-go/blob/main/examples/durable_agent/local/README.md#production-engine-caller-owned). Same pattern as [Temporal Client](/examples/temporal-client). Details: [In-Process durability](/runtimes/in-process#caller-owned-engine-payload-codec-journal-mac-step-token-key).

## Learn more

<CardGroup cols={2}>
  <Card title="Durable Execution" icon="shield-check" href="/advanced/durable-execution" horizontal>
    Shared reconnect protocol (local, Temporal, and Restate)
  </Card>

  <Card title="In-Process Runtime" icon="laptop" href="/runtimes/in-process" horizontal>
    SDK-built knobs vs caller-owned Engine
  </Card>

  <Card title="Durable Agent (Temporal)" icon="server" href="/examples/durable-agent" horizontal>
    Split worker/agent crash lab
  </Card>

  <Card title="Durable Agent (Restate)" icon="cube" href="/examples/durable-agent-restate" horizontal>
    Single-process embedded-endpoint crash lab
  </Card>
</CardGroup>