Errors

HALO preserves provider-compatible error envelopes where practical and returns stable machine-readable codes for Authentication and selected payment flows.

#Error shapes

{
  "error": {
    "message": "Invalid API Key",
    "type": "invalid_request_error",
    "code": "invalid_api_key"
  }
}

#Status codes

Status	Meaning	Default action
400	Invalid payload, redirect, scope, model, or contract	Fix the request
401	Credential or required proof missing	Authenticate; do not blind retry
403	Invalid credential or blocked resource	Stop and inspect policy
402	Payment is required	Settle or add balance, then retry
409	State or rollout conflict	Refresh state and follow the code
429	Usage or Authentication rate limit	Back off
500	Unexpected server failure	Retry only if idempotent
503	Required dependency or capacity unavailable	Back off with jitter

#Retry policy

Retry GET requests and explicitly idempotent operations with bounded backoff.
Do not replay one-time authorization codes, refresh tokens, or payment proofs blindly.
Streaming requests require application-level handling because a partial response may have already reached the client.
Respect Retry-After when it is present.

#Error shapes

#Status codes

#Retry policy

#Security failures