Errors and close codes

Error objects

An err envelope and an s_err both carry an error object:

{ "code": "invalid_params", "message": "…", "retriable": false, "data": null }

code is a string. retriable is explicit on every instance: a callee may mark a normally retriable failure as permanent, or the reverse. data is optional structured detail.

Registered codes

Code	Retriable by convention	Meaning
`parse_error`		A frame or envelope could not be decoded.
`unsupported_version`		The peers share no protocol version.
`unauthorized`		The credential was not accepted.
`forbidden_scope`		The credential lacks the scope this call needs.
`method_not_found`		No such method or tool.
`invalid_params`		The arguments do not match the tool's schema or rules.
`capability_not_announced`		The peer has not announced this capability.
`capability_rejected`		An announced capability was refused, e.g. a reserved name.
`capability_unavailable`		The capability was withdrawn while the call was in flight.
`node_offline`	yes	The node the call is for is not reachable from here.
`connection_lost`	yes	The connection dropped with the call in flight.
`stream_lagged`	yes	A gap was detected in a stream's chunks.
`credit_violation`		A stream sender exceeded its flow-control credit.
`payload_too_large`		A frame or value exceeded a declared limit.
`overloaded`	yes	Too many requests in flight.
`canceled`		The call was cancelled.
`timeout`	yes	The call did not finish in time.
`internal`		Something failed inside the callee.

Capabilities may define additional codes. They MUST NOT collide with this registry.

Websocket close codes

Code	Meaning
`1000`	Graceful close.
`4400`	Unsupported protocol version.
`4401`	Authentication failed, or the credential was revoked.
`4408`	Unknown frame kind, or a malformed frame.
`4409`	Flow-control violation.

Errors and close codes

Error objects

Registered codes

Websocket close codes

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