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All errors from the Veto API use the same response envelope: 
{
  "error": {
    "code": "AGENT_NOT_FOUND",
    "message": "Agent not found in this workspace"
  }
}
code is a machine-readable string you can match against in code. message is a human-readable description of the problem.

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Error codes

HTTP statusCodeMeaning
400VALIDATION_ERRORRequest body or query parameters failed validation
401UNAUTHORIZEDMissing or invalid API key
403FORBIDDENValid key but insufficient scope for this operation
404AGENT_NOT_FOUNDAgent does not exist in this workspace
404POLICY_NOT_FOUNDPolicy does not exist
404API_KEY_NOT_FOUNDAPI key does not exist
429RATE_LIMITEDRate limit exceeded
500INTERNAL_ERRORInternal server error

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Rate limit errors

When you receive a 429, the response includes a Retry-After header with the number of seconds until the rate limit window resets: 
HTTP/1.1 429 Too Many Requests
Retry-After: 34
Wait the indicated number of seconds before retrying.

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SDK error handling

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Node.js

The Veto Node.js SDK exposes three error classes:
  • VetoError — base class for all Veto errors. Has .code (string) and .statusCode (number).
  • UnauthorizedError — thrown on 401 responses. Extends VetoError.
  • RateLimitError — thrown on 429 responses. Extends VetoError. Has .retryAfterMs (milliseconds until reset).
import { VetoClient, VetoError, UnauthorizedError, RateLimitError } from '@useveto/node';

const veto = new VetoClient({ apiKey: 'veto_...' });

try {
  const result = await veto.authorize('agent-uuid', 'file.write', { path: '/tmp/out.txt' });
} catch (err) {
  if (err instanceof RateLimitError) {
    // Wait the indicated time then retry
    await sleep(err.retryAfterMs);
    retry();
  } else if (err instanceof UnauthorizedError) {
    // API key is missing or invalid
    console.error('Check your API key:', err.message);
  } else if (err instanceof VetoError) {
    // Any other Veto API error
    console.error(`API error ${err.statusCode} [${err.code}]:`, err.message);
  } else {
    throw err;
  }
}

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Python

from veto import VetoClient, VetoError, UnauthorizedError, RateLimitError
import time

client = VetoClient(api_key="veto_...")

try:
    result = client.authorize("agent-uuid", "file.write", {"path": "/tmp/out.txt"})
except RateLimitError as e:
    # e.retry_after_ms contains milliseconds until reset
    time.sleep(e.retry_after_ms / 1000)
except UnauthorizedError as e:
    print("Check your API key:", e.message)
except VetoError as e:
    print(f"API error {e.status_code} [{e.code}]: {e.message}")