diff --git a/src/broker-amqp.ts b/src/broker-amqp.ts
index 62c5e51..9b8db7c 100644
--- a/src/broker-amqp.ts
+++ b/src/broker-amqp.ts
@@ -373,7 +373,7 @@ function toEnvelope<T>(msg: amqp.ConsumeMessage): Envelope<T> {
 
 /** AMQP topic matching: `*` matches one word, `#` zero or more. Used to fan a shared queue's
  *  deliveries out to the handlers whose pattern actually matches the routing key. */
-function topicMatches(pattern: string, key: string): boolean {
+export function topicMatches(pattern: string, key: string): boolean {
   return matchFrom(pattern.split("."), 0, key.split("."), 0);
 }
 
@@ -404,19 +404,19 @@ function matchFrom(p: string[], pi: number, k: string[], ki: number): boolean {
  *  **Why it exists at all.** Until 04-ISSUES/127 every module passed the routing key itself, which
  *  worked on this bus and derived into a namespace nobody owns on the one being built. Converting the
  *  modules to local names without this would have broken the mesh that is actually running. */
-function routingKeyFor(key: string, self: string): string {
+export function routingKeyFor(key: string, self: string): string {
   return key.startsWith("module.") ? key : `module.${self}.${key}`;
 }
 
 /** A local pattern as this bus's binding. `**` is the mesh's wildcard for the rest of a name; here
  *  that is `#`, and on the bus being built it is `>`. Neither spelling appears in a manifest. */
-function bindingFor(pattern: string): string {
+export function bindingFor(pattern: string): string {
   const here = pattern.split(".").map((part) => (part === "**" ? "#" : part)).join(".");
   if (here === "#") return "#";
   return here.startsWith("module.") ? here : `module.${here}`;
 }
 
 /** A routing key as the local name a handler and a manifest both use: the emitter and the event. */
-function localKeyFor(routingKey: string): string {
+export function localKeyFor(routingKey: string): string {
   return routingKey.startsWith("module.") ? routingKey.slice("module.".length) : routingKey;
 }
diff --git a/test/wire-unchanged.test.ts b/test/wire-unchanged.test.ts
new file mode 100644
index 0000000..2d80144
--- /dev/null
+++ b/test/wire-unchanged.test.ts
@@ -0,0 +1,68 @@
+/**
+ * **The old bus's wire is byte-identical after the rename, and this is the test that lets the change
+ * be merged to a running mesh.**
+ *
+ * Every module's event names were converted from the old bus's routing keys to local names
+ * (novox/hq 04-ISSUES/127), and the old bus's client maps them back. If that mapping is wrong
+ * anywhere, a live mesh's events stop being delivered — silently, because a binding that matches
+ * nothing is not an error.
+ *
+ * So this pins the mapping against the literal routing keys the mesh used before, taken from the
+ * manifests as they were. It needs no bus: it is about a string.
+ */
+import assert from "node:assert/strict";
+import { test } from "node:test";
+
+import { routingKeyFor, bindingFor, localKeyFor, topicMatches } from "../dist/broker-amqp.js";
+
+test("a converted emit produces the routing key the mesh published before", () => {
+  // left: what the module's code says now. right: what went on the wire before, unchanged.
+  const same: [string, string, string][] = [
+    ["plex", "playback.started", "module.plex.playback.started"],
+    ["sonarr", "download.completed", "module.sonarr.download.completed"],
+    ["builder", "built", "module.builder.built"],
+    ["mesh-catalog", "upgraded", "module.mesh-catalog.upgraded"],
+    ["keycloak", "user.created", "module.keycloak.user.created"],
+    ["mesh-vault", "secret.rotated", "module.mesh-vault.secret.rotated"],
+  ];
+  for (const [self, local, before] of same) {
+    assert.equal(routingKeyFor(local, self), before, `${self} emitting ${local}`);
+  }
+});
+
+test("a converted subscription binds what it bound before", () => {
+  const same: [string, string][] = [
+    ["builder.built", "module.builder.built"],
+    ["*.download.completed", "module.*.download.completed"],
+    ["*.usage.*", "module.*.usage.*"],
+    // The audit logger's "everything": `#` on this bus, and it must stay `#`.
+    ["**", "#"],
+  ];
+  for (const [declared, before] of same) {
+    assert.equal(bindingFor(declared), before, `consuming ${declared}`);
+  }
+});
+
+test("a handler still matches what the bus delivers", () => {
+  // The key a handler is given is the local one now, and the pattern it compares against is local
+  // too — so the pair must still meet for every case the mesh actually has.
+  const pairs: [string, string][] = [
+    ["builder.built", "module.builder.built"],
+    ["*.download.completed", "module.sonarr.download.completed"],
+    ["*.usage.*", "module.anthropic-consumer.usage.session"],
+    ["**", "module.anything.at.all"],
+  ];
+  for (const [pattern, delivered] of pairs) {
+    assert.ok(
+      topicMatches(pattern, localKeyFor(delivered)),
+      `${pattern} no longer matches ${delivered}, so a running module would stop reacting`,
+    );
+  }
+});
+
+test("a routing key already in the old form is left alone", () => {
+  // Belt for the transition: anything not yet converted still goes out as it did, so a module built
+  // from an older manifest keeps working beside one built from a current manifest.
+  assert.equal(routingKeyFor("module.plex.playback.started", "plex"), "module.plex.playback.started");
+  assert.equal(bindingFor("module.builder.built"), "module.builder.built");
+});