Enum Undeliverable 

pub enum Undeliverable {
    WorkerUnreachable {
        reason: String,
    },
    DeliveryFailed {
        reason: String,
    },
    Unservable {
        reason: String,
    },
}

Why one delivery attempt did not place its task with a worker.

The two variants are the whole reason this is a type rather than a bool: they carry opposite obligations for the worker’s registration, and conflating them either destroys a live worker’s registration or keeps a dead one’s forever.

Variants

WorkerUnreachable

The transport reports the worker is gone — a closed gRPC stream, a liminal connection the supervisor no longer owns.

The caller deregisters it. This is the pre-existing behaviour of the closed-stream path, now reached for a reason that is true of both transports rather than inferred from a missing sender.

Fields

reason: String

Operator-facing reason, named by the transport that observed it.

DeliveryFailed

The delivery failed while the worker is alive — a liminal reply that did not arrive in time, a full channel, a drain that closed the gate mid-push.

🔴 The caller keeps the registration and withdraws only its own token. Deregistering here would destroy a healthy worker because one delivery was slow, which is exactly the failure the typed outcome exists to prevent.

Fields

reason: String

Operator-facing reason, named by the transport that observed it.

Unservable

The task can NEVER be placed: the transport proved its encoded frame is larger than the connection’s whole outbound buffer, a bound every worker connection shares because one supervisor builds them all from one LimitsConfig. No other candidate can carry it, no retry can, and every attempt writes one more lease for a step that never runs.

The caller keeps the registration, withdraws its own token, and settles the dispatch TERMINALLY — no next candidate, no park, no attempt-neutral re-arm. This is the class the outbox dead-letters on first observation and the engine-seam bridge reports as terminal:; it used to be reported as Undeliverable::DeliveryFailed here, which read as retryable and spent a whole attempt budget on a certainty.

Fields

reason: String

Operator-facing reason naming the frame’s size, the bound and the key that sets it.

Implementations

impl Undeliverable

pub fn is_unservable(&self) -> bool

Whether this refusal is terminal for the dispatch — see Undeliverable::Unservable.

pub fn deregisters_worker(&self) -> bool

Whether the caller should remove this worker from the registry.

true only for Undeliverable::WorkerUnreachable. Expressed as a method so the decision has one definition rather than a match repeated at every call site, where the two arms could drift apart.

pub fn reason(&self) -> &str

The operator-facing reason, whichever variant this is.

Trait Implementations

impl Debug for Undeliverable

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

Formats the value using the given formatter.