Enum PreemptionReason 

pub enum PreemptionReason {
    PriorityPreemption,
    QuotaRebalance,
    BurstCreditExhausted,
    BudgetExhausted,
    CostCapEviction,
    OperatorDrain,
    OperatorMigProfileChange,
    MaintenanceWindow,
    PolicyViolationRecovery,
}

Typed reasons for which an admission was rejected or an existing lease was preempted. Phase 218 enumerates these up front so the admission, audit, and DRA layers all agree on the vocabulary.

The reason MUST be present on every preemption emit. There is no Other(String) variant on purpose: a generic kill path is exactly what the typed-lifecycle rule rejects.

New reasons require a design-doc update plus a typed regression test that asserts the reason fires in the case it names. Adding a reason is a vocabulary change, not a runtime config knob.

Variants

PriorityPreemption

Higher-priority admitted work is allowed to reclaim resources from lower-priority preemptible work.

QuotaRebalance

Tenant or project usage must be moved back inside its configured fair-share/quota envelope. Distinct from BurstCreditExhausted: a QuotaRebalance typically admitted a different tenant.

BurstCreditExhausted

The tenant’s token-bucket burst credit reached zero while the request required burst capacity beyond hard quota. No other tenant was admitted; the workload was rejected for exceeding its own configured burst envelope.

BudgetExhausted

Tenant budget or spend policy is exhausted and the work is configured as preemptible on budget exhaustion.

CostCapEviction

Phase 216 economics policy requires eviction because a hard cost cap can no longer be satisfied.

OperatorDrain

An operator initiated node/cell drain.

OperatorMigProfileChange

An operator initiated GPU MIG profile recompose. Shared with Phase 221 dynamic MIG profile recompose so audit logs distinguish operator-driven GPU repartitioning from ordinary priority preemption.

MaintenanceWindow

A scheduled maintenance policy requires the resource to be cleared.

PolicyViolationRecovery

The system detected a previously admitted lease no longer satisfies a mandatory policy and must fail closed or recover. Emit MUST carry a typed policy_id naming the violated policy — emit without policy_id is a typed error, not a string default.

Implementations

impl PreemptionReason

pub fn as_str(self) -> &'static str

Stable wire / log identifier. Used by audit emit, DRA failure types, and Phase 219 docs lint. MUST be stable across minor versions: external collectors group on this string.

pub fn human_summary(self) -> &'static str

Tooltip-grade operator-readable phrase for this preemption reason. Mirrors the [RejectionReason::human_summary] shape so dashboard / CLI surfaces can render typed preemption reasons without re-deriving the prose.

as_str() remains the wire-format-grade snake_case label SIEM rules and audit collectors group on; human_summary() is the rendering helper. They are NOT interchangeable.

The string is intentionally short (one line, no terminal punctuation) so a renderer can compose it inline. The runbook at docs/runbooks/preemption-explanations.md is the long-form operator-action prose; this helper is the tooltip-grade sibling.

Slice 73 lands the helper without dashboard wiring — there is no preemption panel yet. When that surface lands it can read this method directly.

Trait Implementations

impl Clone for PreemptionReason

fn clone(&self) -> PreemptionReason

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PreemptionReason

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for PreemptionReason

fn deserialize<__D>( __deserializer: __D, ) -> Result<PreemptionReason, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for PreemptionReason

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

Formats the value using the given formatter.

impl Hash for PreemptionReason

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for PreemptionReason

fn eq(&self, other: &PreemptionReason) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for PreemptionReason

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for PreemptionReason

impl Eq for PreemptionReason

impl StructuralPartialEq for PreemptionReason