Scheduling first filters for policy compliance, then ranks eligible capacity. Mandatory filters include tenant authorization, data location, workload compatibility, resource requirements, network access, budget and deadlines. Unavailable capacity MUST NOT cause a silent relaxation of these constraints.
Lease contract#
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| Field | Required meaning |
|---|---|
| task_id and attempt_id | The logical request and this execution opportunity |
| node_id and lease_id | The selected node and unique lease |
| fencing_token | Monotonically increasing generation for the task |
| expires_at | Authority expiry evaluated by the coordinator |
| scope | Permitted objects, operations and resource reservation |
LEASE-01 Allocation MUST create the reservation, attempt and lease within one consistency boundary. LEASE-02 State-changing submissions MUST match the current attempt and fencing token. A recovered executor with an older token cannot overwrite the current delivery or cause a payment.
Renewal and partitions#
Only a current, unexpired lease may be renewed. The authority records the prior expiry, new expiry and renewing identity. Missing heartbeats stop new allocation and initiate a health review; lease expiry determines the existing authority to commit work.
An executor without valid authority MUST NOT begin a new external side effect. It should stop or isolate ongoing output according to its workload profile. Downstream systems must also enforce generation or idempotency controls to prevent stale actions; a coordinator cannot guarantee global exactly-once behavior across systems it does not control.
Late delivery#
A receipt admitted after lease expiry or supersession MUST NOT become the active delivery. The coordinator records the admission time, state version and generation. Later expiry does not invalidate a delivery admitted under valid authority. Duplicate submission returns the original record. Lease duration, renewal margin and clock tolerance require versioned configuration and fault tests.