Module rpc

Expand description

JSON-RPC 2.0 host <-> worker types + the versioned init handshake (spec §5).

Structs§

InitAnnounce: The worker’s first frame after connect (spec §5 init handshake). Carries the connection token (§6): the host generated it and passed it to the worker out-of-band (a 0600 file); the host verifies it here to reject any other local process that raced the loopback port.
JsonRpcVersion: A ZST that (de)serializes as the constant string “2.0”, rejecting anything else.
RpcNotification: A JSON-RPC 2.0 notification (no id). The worker’s init handshake is a notification — { jsonrpc:"2.0", method:"worker/init", params:<InitAnnounce> } — so the first frame rides the SAME JSON-RPC parse path as every later frame (spec §5): the host reads frame 1, parses it as a notification, checks method == INIT_METHOD, and deserializes params as InitAnnounce. InitAnnounce is never sent as a naked object.
RpcRequest: A JSON-RPC 2.0 request (host -> worker).

RpcId: JSON-RPC 2.0 id: a number, a string, or null. Null is required by JSON-RPC 2.0 §5 on an error response to a request whose id couldn’t be determined (parse error / invalid request), so the host must be able to receive it — otherwise a worker’s parse-error reply fails to deserialize and its error is silently swallowed. (The host never sends a null id.)
RpcResponse: A JSON-RPC 2.0 response (worker -> host): result XOR error, never both, never neither (JSON-RPC 2.0 §5). Modeled as an untagged enum of two complete structs so the illegal states are unrepresentable. Deliberately NOT #[serde(flatten)] over an untagged inner enum — that serde combination double-buffers (flatten → map, untagged → Content) and is a known deserialize failure mode (fails outright or degrades integers to floats).

INIT_METHOD: The method name of the worker’s init-handshake notification (spec §5).
PROTOCOL_VERSION: The protocol version this host speaks. The worker must announce a matching value in its init frame, else the host rejects it (WORKER_INCOMPATIBLE).