tunnel_offline

No agent connected. Answered with 503.

What it means

The Tunnel exists only while its agent holds the control connection, and no agent is connected for that hostname right now – or the one that is will not take new streams.

What to do

Retry with backoff. On the agent's side: start the tunnel client and keep it connected.

The body

{
  "type": "https://tigby.eu/problems/tunnel_offline",
  "title": "No agent connected",
  "status": 503,
  "detail": "…what was refused, naming this request's own values",
  "code": "tunnel_offline",
  "doc_url": "https://docs.tigby.eu/errors/tunnel_offline",
  "agent_hint": "…the next step, for software"
}

Branch on code. The detail names this request's own Handle, id or limit and is not part of the contract.