Function invoke_json 

pub async fn invoke_json<U, I, O>(
    upstream: &U,
    target: &U::Target,
    request: WireRequest<I>,
    limits: CodecLimits,
) -> Result<JsonInvocation<O>, TransformError>
where
    U: Upstream,
    I: Serialize + DeclaredFields,
    O: DeserializeOwned + DeclaredFields,

Send exactly one already-prepared, typed target request. This helper neither routes nor retries. Dropping its future cancels further adapter work; any upstream side effect remains subject to that operation’s recovery contract.

Only declared fields are encoded/returned. JSON Schema, arguments and other formal JSON values remain intact. The host enforces deadlines and stream idle limits, and replaces authentication according to Upstream::send.