node-tools/src/broker-nats.ts

@@ -361,9 +361,18 @@ export async function connectNats(
       const sub = conn.subscribe(subject);
       subs.push(sub);
       void (async () => {
-        for await (const msg of sub) {
-          const body = answer(msg.subject, msg.data);
-          if (body) msg.respond(body);
+        // **A refusal here is said, never fatal** (novox/hq 04-ISSUES/217). This serves discovery —
+        // what the runtime says about itself — not the work; a bus that refuses it costs the mesh
+        // seeing this runtime, not the runtime's tools and handlers. Unhandled, the refusal ended the
+        // process and every per-module container crash-looped on 2026-10-03.
+        try {
+          for await (const msg of sub) {
+            const body = answer(msg.subject, msg.data);
+            if (body) msg.respond(body);
+          }
+        } catch (err) {
+          console.log(`[mesh-tools] the bus refused ${subject}: ${err instanceof Error ? err.message : String(err)}; ` +
+            "discovery will not see this runtime there, and it serves on");
         }
       })();
       return () => sub.unsubscribe();

node-tools/test/fixtures/refusing-nats.conf

@@ -0,0 +1,10 @@
+# A bus that refuses one subject: what the mesh's grants do to a subject they do not name (issue 217).
+authorization {
+  users = [
+    { user: "runtime", password: "runtime", permissions: {
+        publish: { allow: [">"] }
+        subscribe: { allow: [">"], deny: ["$SRV.PING.>"] }
+    } }
+  ]
+}
+jetstream: enabled

node-tools/test/refused.test.ts

@@ -0,0 +1,37 @@
+/**
+ * A refused announcement is said and never fatal (novox/hq 04-ISSUES/217): against a bus whose
+ * permissions refuse one discovery subject, the runtime's raw subscription is refused, logged, and
+ * the process keeps serving — its tools still answer.
+ *
+ *   docker run -d --rm --name t -p 14233:4222 -v $PWD/test/fixtures/refusing-nats.conf:/c.conf nats:2.10-alpine -c /c.conf
+ *   MESH_TEST_REFUSING_NATS=nats://127.0.0.1:14233 node --test --experimental-strip-types test/refused.test.ts
+ */
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import { connectNats } from "../dist/broker-nats.js";
+
+const url = process.env.MESH_TEST_REFUSING_NATS;
+
+test("a refused discovery subscription is logged and the runtime serves on", async (t) => {
+  if (!url) return t.skip("MESH_TEST_REFUSING_NATS unset");
+  const bus = await connectNats({ url, user: "runtime", password: "runtime", module: "alpha", node: "anchor" });
+  const said: string[] = [];
+  const log = console.log;
+  console.log = (...a: unknown[]) => said.push(a.join(" "));
+  const crashed: unknown[] = [];
+  const onRejection = (e: unknown) => crashed.push(e);
+  process.on("unhandledRejection", onRejection);
+  try {
+    (bus as unknown as { raw: (s: string, f: () => Uint8Array | undefined) => () => void }).raw("$SRV.PING.>", () => undefined);
+    const stop = await bus.handle("alpha.ping", async () => ({ pong: true }));
+    for (let i = 0; i < 50 && !said.some((s) => s.includes("the bus refused $SRV.PING.>")); i++) await new Promise((r) => setTimeout(r, 50));
+    console.log = log;
+    assert.ok(said.some((s) => /the bus refused \$SRV\.PING\.>.*serves on/.test(s)), said.join("\n"));
+    assert.equal(crashed.length, 0, `the refusal escaped: ${String(crashed[0])}`);
+    stop();
+  } finally {
+    console.log = log;
+    process.off("unhandledRejection", onRejection);
+    await bus.close();
+  }
+});