Enum CancellationWireMessage 

pub enum CancellationWireMessage {
    Legacy2024 {
        sender: CancellationSender,
        params: CancelledParams,
    },
    Modern2026 {
        sender: CancellationSender,
        params: FinalCancelledNotificationParams,
    },
}

An era-selected notifications/cancelled JSON-RPC notification.

This is intentionally separate from the broad ClientNotification and ServerNotification unions. Those unions preserve schema-open final extension members for generic routing. This codec is the boundary at which FastMCP assigns cancellation semantics without inferring meaning from schema-open extension members.

The codec is for JSON-RPC transports such as stdio. Modern Streamable HTTP cancellation is a response-stream close and must not be translated into a second notifications/cancelled POST by a transport integration.

Variants

Legacy2024

Exact MCP 2024-11-05 cancellation parameters.

Fields

sender: CancellationSender

Peer that originated the notification.

params: CancelledParams

Closed legacy cancellation payload.

Modern2026

MCP 2026-07-28 cancellation parameters.

Notification metadata is optional for either sender and is never synthesized by this codec.

Fields

sender: CancellationSender

Peer that originated the notification.

params: FinalCancelledNotificationParams

Final cancellation payload.

Implementations

impl CancellationWireMessage

pub fn decode( era: ProtocolEra, sender: CancellationSender, request: &JsonRpcRequest, ) -> Result<Self, CancellationWireCodecError>

Decodes one cancellation notification using the already-negotiated era and the peer that supplied the frame.

This method deliberately does not infer an era from optional fields. The caller must negotiate once before decoding control traffic.

pub const fn era(&self) -> ProtocolEra

Returns the exact selected protocol era.

pub const fn sender(&self) -> CancellationSender

Returns the peer that originated this cancellation notification.

pub fn encode(&self) -> Result<JsonRpcRequest, CancellationWireCodecError>

Encodes this typed cancellation as an ID-free JSON-RPC notification.

Local construction receives the same era-specific validation as peer ingress. A schema-open extension never acquires cancellation semantics through this codec.

Trait Implementations

impl Clone for CancellationWireMessage

fn clone(&self) -> CancellationWireMessage

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CancellationWireMessage

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.