mesh-tools — the tool runtime and AMQP broker binding

The per-node process that makes a module's tools serve on the mesh:
- broker-amqp.ts: a concrete AMQP implementation of the sdk's Broker
  contract (request/reply over a reply queue + correlation id, publish/
  subscribe over a topic exchange). Kept here, not in the sdk, so a
  broker-client change never rebuilds a module (ADR 0044).
- runtime.ts: bind the broker, import the assigned modules' tool
  entrypoints (each registers as it loads), serveTools. The thin wrapper.
- main.ts: the entrypoint, configured by MESH_BROKER_URL + MESH_TOOL_MODULES.
- Dockerfile: the container a node runs it as.

Verified over a REAL broker: the test spins LavinMQ (the mesh's broker),
the runtime serves a registered tool, a separate connection invokes it by
name over AMQP and gets the result, and an unknown tool is refused over
the wire. So 'modules can serve' is now running-on-the-mesh, not just
proven in a mock.

Claude-Session: https://claude.ai/code/session_01LrgweAeERJYBg88c5cKDzF

src/main.ts

@@ -0,0 +1,38 @@
+// The runnable entrypoint. Reads its configuration from the environment the host resolved for it,
+// connects the mesh broker, and serves the assigned modules' tools until stopped.
+//
+//   MESH_BROKER_URL     amqp://…               the mesh broker
+//   MESH_TOOL_MODULES   /path/a,/path/b,…      compiled tool entrypoints of the assigned modules
+
+import { connectAmqp } from "./broker-amqp.js";
+import { runTools } from "./runtime.js";
+
+async function main(): Promise<void> {
+  const url = requireEnv("MESH_BROKER_URL");
+  const moduleEntrypoints = (process.env.MESH_TOOL_MODULES ?? "")
+    .split(",")
+    .map((s) => s.trim())
+    .filter(Boolean);
+
+  const broker = await connectAmqp(url);
+  const stop = await runTools({ broker, moduleEntrypoints });
+
+  const shutdown = async (): Promise<void> => {
+    stop();
+    await broker.close();
+    process.exit(0);
+  };
+  process.on("SIGTERM", () => void shutdown());
+  process.on("SIGINT", () => void shutdown());
+}
+
+function requireEnv(name: string): string {
+  const v = process.env[name];
+  if (!v) {
+    console.error(`mesh-tools: ${name} is not set — the runtime cannot serve without it`);
+    process.exit(1);
+  }
+  return v;
+}
+
+void main();