Struct StreamEvent 

#[non_exhaustive]
pub struct StreamEvent {
    pub seq: Option<u64>,
    pub event: StreamResponse,
}

One event as it travels the queue, carrying the position it holds in the task’s event log.

The position is assigned once, by InMemoryQueueWriter::write, and then travels on both channels — the persistence channel that writes the log and the broadcast channel that feeds SSE. That is what makes the id: a subscriber reads and the seq the store holds the same number by construction rather than by agreement.

The alternative was to count frames at the SSE layer. It would agree with the log until the first lagged consumer, a snapshot frame, or a failed append, and a resumption offset that is off by one is worse than none: the client silently misses an event and has no way to know.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

seq: Option<u64>

This event’s position in its task’s log, when it has one.

None for frames the server synthesized rather than the agent emitting — the SubscribeToTask snapshot, and the terminal frame the reattach hook builds from stored state. Those are not in the log, so they carry no id: and a resuming client’s offset is unaffected by having seen them.

event: StreamResponse

What the agent emitted.

Implementations

impl StreamEvent

pub const fn at(seq: u64, event: StreamResponse) -> StreamEvent

An event at a known log position.

pub const fn unpositioned(event: StreamResponse) -> StreamEvent

An event with no log position: synthesized by the server, not emitted by the agent.

Trait Implementations

impl Clone for StreamEvent

fn clone(&self) -> StreamEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StreamEvent

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

Formats the value using the given formatter.