# Errors
URL: /docs/agent/api-reference/errors

The three errors the Agent SDK throws on its own — a stalled turn, a dead bridge, and an invalid spec.



```ts
import { PromptTimeoutError, BridgeDisconnectedError, AgentSpecValidationError } from "alineo";
```

All three extend the Core SDK's `WorkflowError`, so one `catch` for that covers them along with every
[sandbox error](/docs/core/api-reference/errors).

## PromptTimeoutError [#prompttimeouterror]

Thrown from an `agent.prompt()` or `agent.bash()` stream that goes quiet — no event at all from Pi — for longer
than the inactivity window: **180 s** by default, or `inactivityTimeoutMs` on the `prompt()` call. The bridge's own
keep-alive pings don't count; they only prove the connection is open, not that Pi is making progress.

| Property    | Type     | Description                          |
| ----------- | -------- | ------------------------------------ |
| `timeoutMs` | `number` | The window that elapsed.             |
| `bridgeUrl` | `string` | The bridge the stream was read from. |

A long-thinking model that streams nothing while it reasons can trip this. Raise `inactivityTimeoutMs` for those
rather than retrying.

## BridgeDisconnectedError [#bridgedisconnectederror]

Thrown when a stream's connection closes before the bridge sent its end-of-turn marker. That means the bridge
process inside the container died mid-turn — a crash, an OOM kill — not that Pi finished. Without this error the
turn would look like a clean, empty success.

| Property    | Type     | Description                          |
| ----------- | -------- | ------------------------------------ |
| `bridgeUrl` | `string` | The bridge whose connection dropped. |

The container is usually still up. [`Alineo.resume()`](/docs/agent/api-reference/alineo#alineoresume) restarts the
bridge and continues the session; the turn that was running is gone.

## AgentSpecValidationError [#agentspecvalidationerror]

Thrown by `Alineo.start()` and `validateAgentSpec()` when a spec fails validation. It reports every failing field
at once, not just the first.

| Property  | Type                        | Description                                             |
| --------- | --------------------------- | ------------------------------------------------------- |
| `message` | `string`                    | A readable, multi-line summary — print it as-is.        |
| `issues`  | `{ path, message, code }[]` | One entry per failing field, for handling them in code. |

```ts
try {
  await Alineo.start(spec, { adapter });
} catch (err) {
  if (err instanceof AgentSpecValidationError) {
    for (const issue of err.issues) console.error(issue.path.join("."), issue.message);
  }
  throw err;
}
```