The sdk names no transport, and fixtures say what two implementations may not disagree about #8
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# Conformance fixtures
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What two implementations of the mesh's module protocol may not disagree about
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([novox/hq ADR 0074](https://git.novox.be), design 19). A fixture is data, not prose: every
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implementation produces it and consumes it, and an implementation that passes the fixtures for a
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capability **claims** that capability.
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## What "byte-for-byte" means, and what it cannot
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ADR 0074 says the fixtures must match byte for byte. Taken literally that is more than the mesh
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needs and more than two languages can give:
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- **The envelope is exact.** The subject, the set of required headers, each header's name, and
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the format of each value. This is what an implementation can get wrong in a way that makes two
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meshes silently ignore each other, so this is what is pinned.
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- **The body is not.** It is the module's own payload, opaque to the mesh, and its serialisation
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is the language's. Go's `encoding/json` sorts a map's keys; JavaScript's `JSON.stringify` keeps
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insertion order. Demanding identical bytes there would mean committing every implementation to
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a canonical JSON encoder — a large promise, bought for a property the mesh never uses. The
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fixture pins that the body **round-trips**: what goes in comes out equal.
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So: exact where disagreement is invisible, semantic where it is not. Stated here because
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"byte-for-byte" read strictly would have sent somebody implementing a canonical encoder.
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## Running them
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The TypeScript implementation: `node conformance/run.mjs` (against a NATS server; see the file).
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The Go implementations read this directory by sibling path, the way the lab finds its siblings.
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## Layout
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events/ one emitted event, and what it must look like on the wire
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{
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"capability": "events",
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"name": "a module emits an event",
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"why": "The envelope is what two implementations can disagree about without either failing: a missing header, a header spelled differently, or a body nested where metadata belongs. None of those stop a mesh running; they stop it reacting.",
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"given": {
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"module": "shop",
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"node": "one",
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"key": "order.placed",
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"body": { "id": "a1", "total": 12 },
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"headers": {
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"x-event-id": "0123456789abcdef0123456789abcdef",
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"x-source": "shop",
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"x-node": "one",
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"x-time": "2026-09-26T12:00:00Z",
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"content-type": "application/json"
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}
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},
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"wire": {
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"subject": "mesh.mod.shop.event.order.placed",
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"requiredHeaders": ["x-event-id", "x-source", "x-node", "x-time", "content-type"],
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"optionalHeaders": ["x-causation-id", "x-schema"],
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"headerFormats": {
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"x-time": "RFC3339",
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"content-type": "application/json",
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"x-event-id": "^[0-9a-f]{32}$"
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},
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"payloadIs": "the body alone, not the envelope",
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"keyRecoveredFrom": "the subject, after the .event. token"
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},
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"refuses": [
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{
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"what": "an envelope nested in the payload",
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"why": "an implementation that publishes the whole envelope as the body passes all of its own tests and is unreadable to every other"
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},
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{
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"what": "a missing x-event-id",
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"why": "delivery is at-least-once and only the emitter can say which of two messages is a redelivery"
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},
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{
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"what": "an x-source that differs from the subject's module",
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"why": "the bus enforces the namespace, so a disagreement means the envelope is lying about its origin"
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}
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]
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}
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@@ -19,7 +19,7 @@ export interface ToolDefinition {
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}
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/**
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* The metadata that rides an event as AMQP headers (novox/hq ADR 0042). An event's identity and
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* The metadata that rides an event as message headers (novox/hq ADR 0042). An event's identity and
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* provenance live here, not in the body, so a consumer — or the broker, or an audit tool — reads
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* who/when/what without parsing the payload. An unknown `x-` header is ignored, not refused: an
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* event is observed by parties that need not all understand every header.
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+1
-1
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// credential — just the broker's topic routing). Declared as emits/consumes on the manifest so the
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// mesh knows the event graph.
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//
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// Identity and provenance ride as AMQP headers, not in the body (novox/hq ADR 0042): a consumer —
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// Identity and provenance ride as message headers, not in the body (novox/hq ADR 0042): a consumer —
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// or the broker, or an audit tool — reads who/when/what without parsing the payload, and the body
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// is only the domain payload. This surface hides the header/exchange/queue mechanics; a module
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// names a type and a body and never sees the wire.
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@@ -25,7 +25,7 @@ export interface Broker {
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/**
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* How a module obtains its broker. The hosting runtime sets this once; module code calls broker()
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* without knowing the concrete binding. Keeping the binding out of the sdk is deliberate — the sdk
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* carries the contract, not a specific AMQP client build.
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* carries the contract, not a specific broker client build.
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*/
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let binding: (() => Broker) | undefined;
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Block a user