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

# Error Codes

> Standard error codes returned by all compliant SAMVAD agents.

All protocol errors are returned as a response envelope with `"status": "error"` and an `error` object:

```json theme={null}
{
  "status": "error",
  "error": {
    "code": "RATE_LIMITED",
    "message": "Sender exceeded 10 requests per minute"
  }
}
```

## Code reference

| Code                    | HTTP | Meaning                                                                                                 |
| ----------------------- | ---- | ------------------------------------------------------------------------------------------------------- |
| `AUTH_FAILED`           | 401  | Invalid or missing signature, unknown sender key, or missing Bearer token for an `authenticated` skill  |
| `REPLAY_DETECTED`       | 401  | Nonce has already been seen within the 5-minute replay window                                           |
| `SKILL_NOT_FOUND`       | 404  | Skill ID does not exist on this agent                                                                   |
| `SCHEMA_INVALID`        | 400  | Payload failed input schema validation (missing required field, wrong type, exceeded `maxLength`, etc.) |
| `INJECTION_DETECTED`    | 400  | Payload flagged by the prompt injection scanner                                                         |
| `DELEGATION_EXCEEDED`   | 400  | Delegation token's `scope` does not include the called skill, or `maxDepth` has reached 0               |
| `RATE_LIMITED`          | 429  | Sender exceeded the per-sender request rate declared in the agent card                                  |
| `TOKEN_BUDGET_EXCEEDED` | 429  | Sender exhausted their daily token budget; `Retry-After` header gives UTC midnight reset time           |
| `AGENT_UNAVAILABLE`     | 500  | Agent is overloaded, starting up, or the skill handler threw an unhandled exception                     |

## Retry guidance

| Code                    | Retry?                                                      |
| ----------------------- | ----------------------------------------------------------- |
| `AUTH_FAILED`           | No — fix the request (verify key is active, token is valid) |
| `REPLAY_DETECTED`       | Yes — generate a new nonce and timestamp                    |
| `SKILL_NOT_FOUND`       | No — re-fetch the agent card; skill may have been removed   |
| `SCHEMA_INVALID`        | No — fix the payload                                        |
| `INJECTION_DETECTED`    | No — review the payload content                             |
| `DELEGATION_EXCEEDED`   | No — request a new token with appropriate scope/depth       |
| `RATE_LIMITED`          | Yes — back off and retry after a moment                     |
| `TOKEN_BUDGET_EXCEEDED` | Yes — after the `Retry-After` header time                   |
| `AGENT_UNAVAILABLE`     | Yes — exponential backoff                                   |