Receiving calls

What your app receives

Bodies arrive exactly as sent, byte for byte, so signatures from Stripe, GitHub, Svix, or Standard Webhooks verify normally. The relay adds these headers, after removing any copies the sender sent:

HeaderValue

Tsrelay-Sender-Node: The calling machine's name
Tsrelay-Sender-Tags: Its tags, comma-separated
Tsrelay-Sender-Login: Its user, if it isn't a tagged machine
Tsrelay-Sender-Public: true for a call from the internet to a public hook; such a call has no Tsrelay-Sender-Node, -Tags or -Login
Tsrelay-Hook: user/path of the hook
Tsrelay-Call-Id: Also returned to the caller, for matching logs
X-Forwarded-For, -Host, -Proto, -Prefix: The original request, for URL-signing schemes

What senders get

Your app's response goes back to the sender as it is. Errors produced by the relay itself are application/problem+json responses and carry a Tsrelay-Error header. Responses from your app are never marked, including its own 5xx. Tunnel and transport failures have statuses of their own, 561 to 565, so they can't be mistaken for your app's 502, 503 or 504; clients that don't know them treat them as 500. Senders see these:

`Tsrelay-Error`	Status	Meaning
`sender_forbidden`	403	The caller has no sender grant
`hook_not_found`	404	No such hook, not in the caller's channels, or it was deleted/expired while a call was held for it
`body_stalled`	408	The sender's request body stalled past `idleTimeout`
`body_too_large`	413	Over the hook's `maxBodyBytes`, or for a call from the internet, over the relay's `--funnel-max-body-bytes`
`rate_limited`	429	Over the hook's `rateLimit`; `Retry-After` is the limiter's wait, rounded up to whole seconds
`tunnel_unavailable`	561	No tunnel attached within `holdTimeout`; `Retry-After` is `holdTimeout`, but never less than 5 s
`hold_queue_full`	562	No tunnel attached and too many calls are already waiting for one; same `Retry-After`
`tunnel_overloaded`	562	Too many concurrent calls on the tunnel; `Retry-After: 1`
`tunnel_lost`	563	The tunnel dropped mid-call
`upstream_unreachable`	564	The tunnel is up but your app isn't listening
`upstream_timeout`	565	Your app didn't answer within the hook's `responseTimeout`

Every response a sender gets carries Tsrelay-Call-Id, which names the call in the inspector.