Reading guide

Read Nereus Delay in dependency order: begin with the product boundary, follow one message through the system, then move into Broker integrations and operations.

1. Why Nereus Delay? establishes goals, non-goals, and the not-before delivery boundary.
2. Architecture identifies the Command Topic, Shard Runtime, RocksDB, Scheduler, adapters, Oxia, and Object Store.
3. Choose an entry path separates the Direct SDK from the optional Gateway and managed delivery from native acceleration.
4. Lifecycle walkthrough follows one managed message across its durable boundaries.
5. Delay Shard and materialized state explains the log, local state, Object Store, and recovery-unit split.
6. Delivery time and action time fixes the time vocabulary and fail-closed clock behavior.
7. Commands, messages, and receipts separates prepared bytes, queued outcomes, applied results, and destination evidence.
8. Schedule flow follows source-ordered application from preparation to durable message state.
9. Kafka integration and Pulsar integration retain Broker-specific source, resource, timing, and evidence semantics.
10. Scheduler, fairness, and backpressure explains persistent due discovery and two-level DRR.
11. Checkpoints and recovery explains Recovery Set, Recovery Floor, replay, and activation.
12. Correctness invariants is the review checklist for ordering and failure boundaries.
13. Project status records V1 completion and the scope of subsequent evolution.