Errors | Living Brain — Developer Docs

The envelope

Every error shares one shape:

{
  "statusCode": 401,
  "timestamp": "2026-08-27T18:57:27.998Z",
  "path": "/v1/brains",
  "message": "Invalid API key",
  "body": {
    "message": "Invalid API key",
    "error": "Unauthorized",
    "statusCode": 401
  }
}

body carries the original framework response when available — for validation failures it holds per-field messages, which is usually what you want to surface.

Typed errors

Both SDKs raise a typed error per status, so you can branch without string-matching.

import { LivingBrain, LivingBrainError } from "@livingbrain/sdk";
try {
  await client.workspace.getPage({ brainId, slug });
} catch (err) {
  if (err instanceof LivingBrain.NotFoundError) {
    // no such page in this brain
  } else if (err instanceof LivingBrain.TooManyRequestsError) {
    // back off and retry
  } else if (err instanceof LivingBrainError) {
    console.error(err.statusCode, err.message, err.body);
  }
}

Status codes

Code	Meaning	What to do
`400`	Malformed request	Read `body` for per-field detail. Don’t retry unchanged.
`401`	`Missing API key` / `Invalid API key`	Check the `x-api-key` header. See Authentication.
`404`	Not found — or not yours	Confirm the `x-subject-id` owns this brain.
`429`	Rate limited	Back off and retry; the SDKs do this for you.
`5xx`	Server error	Retried automatically.

A 404 is also what you get for a brain that exists but belongs to a different subject — the API doesn’t distinguish, so it can’t be used to probe for other users’ brains.

Retries

Both SDKs retry 429 and 5xx automatically with exponential backoff. Tune per call:

await client.brains.list({ maxRetries: 5, timeoutInSeconds: 30 });

400, 401, and 404 are not retried — they won’t succeed on a second attempt.