jonnify·persistence /echo-persistence/durability-spectrum/two-axes

Module 1 · Dive 1.3

Two axes, one decision.

The shootout measured one thing — the loss window. A second axis is independent of it: does the durable state ever leave the machine? A tier can be strict but single-node, or bounded but replicated. Placing a queue means choosing both. Drop a workload below and see the corner it needs.

§1

The durability–replication plane

interactive
Two independent axes. Right is stronger durability; up is off-box replication. The engines sit where they fall; tap a workload to drop it into the corner it actually needs.
bounded loss · off-box strict · off-box — the goal lossy · single-node strict · single-node durability → replication ↑ Memory BullMQ Oban Champ (async) Champ + Graft
readout · Tap a workload. Its corner is set by two separate questions: how much loss is tolerable, and must the state survive losing the box.
§2

The corner the course reaches

graft.design.md

The plane makes the design’s target precise. Oban owns the bottom-right — strict, but single-node; Champ’s async snapshot reaches off-box but only at a bounded loss, upper-left. The corner no single engine holds is top-right: strict and off-box. Echo Persistence reaches it by composition — Champ accepts (left axis handled by K), Graft commits transactionally and replicates to Tigris (the move up the right edge) — which is why “Champ + Graft” sits where it does. The next chapters build each half; this is the corner they aim at.

§3

References & sources