Causal Block

HLC is prior art. The algorithm was published by Kulkarni, Demirbas, Madappa, Avva & Leone in 2014; we don't claim it. What we expose is a hosted, per-customer, tier-gated HLC surface whose physical-ms floor is sourced from the same Spiral-anchored, NTP/NTS/PTP-disciplined clock that powers every /v1/spiral response — the Spiral coupling is the anchored clock described in the patent pending Spiral provisional.

Standard+ tier covers /v1/causal/now and /v1/causal/merge; Pro+ adds the pure partial-order /v1/causal/compare. Metered separately from the snippet / briefing / deep meters at $0.001 per op (default; configurable per deployment).

Wiring it without forgetting

The two-call shape (now on send, merge on receive) is small, but the accuracy of every later compare depends on every receiver actually calling merge on every stamped message it gets. The recommended pattern is to wrap your message bus once — in one file — so per-call sites can't forget.

// fleet.ts — written once, used everywhere
import { TemporalBlock } from "temporalblock";

const tb = new TemporalBlock({ apiKey: process.env.TEMPORALBLOCK_API_KEY! });
const NODE_ID = process.env.NODE_ID!;

export async function publish(topic: string, payload: object) {
  const { hlc } = await tb.causal.now({ nodeId: NODE_ID });
  return bus.publish(topic, { ...payload, _causal: hlc });
}

export async function subscribe(
  topic: string,
  handler: (msg: any) => Promise<void>,
) {
  return bus.subscribe(topic, async (msg) => {
    if (msg._causal) {
      await tb.causal.merge({ nodeId: NODE_ID, remotes: [msg._causal] });
    }
    return handler(msg);
  });
}

The SDK also ships auto-merge adapters for the most common transports — drop them in instead of writing the wrapper yourself:

• tb.causal.fetch({ nodeId }) — fetch-shaped wrapper that stamps outgoing requests in X-Causal-Stamp and merges any stamp on the response.
• tb.causal.expressMiddleware({ nodeId }) — Express middleware that merges the inbound X-Causal-Stamp header before your handler runs.
• tb.causal.wrapHandler({ nodeId, extract }, handler) — generic wrapper for any message bus (Kafka, MQTT, ROS 2, NATS) — you supply a tiny extract function that returns the stamp from your message shape.

All three are pure SDK glue — they hit the same /v1/causal/{now,merge} endpoints you'd call by hand, billed identically.