node-tools launches every bundle it serves; a child's emit is published as its module (hq ADR 0193)

Every served entrypoint is started as a process speaking MCP over stdio, told its module and node;
one that is not executable is refused by name. The import path, the SDK resolve hook (issue 209)
and the per-registration hand-off go. The one-module form the per-module containers use is still
imported until they move (to-be 38 WP4c). A child's mesh/publish is published as its module and
answered once accepted; a child that dies says why in its own last words. Fixtures are served
through launchers exactly as the builder writes them.

node-tools/src/launch.ts

@@ -13,6 +13,8 @@
 import { spawn, type ChildProcess } from "node:child_process";
 import { accessSync, constants } from "node:fs";
 import type { ToolDefinition } from "@novox/mesh-sdk/tools";
+import { broker, type Envelope } from "@novox/mesh-sdk/messaging";
+import { atWork } from "./broker-nats.js";
 
 /** The protocol version this speaks; a bundle says the same. */
 export const PROTOCOL = "2025-03-26";
@@ -71,29 +73,50 @@ export async function launch(module: string, entry: string, env: NodeJS.ProcessE
         const line = buffered.slice(0, at).trim();
         buffered = buffered.slice(at + 1);
         if (!line) continue;
-        let reply: { id?: number; result?: unknown; error?: { message?: string } };
+        let reply: { id?: number | string; method?: string; params?: unknown; result?: unknown; error?: { message?: string } };
         try {
           reply = JSON.parse(line);
         } catch {
           console.log(`[mesh-tools] ${module}'s bundle said something that is not a reply: ${line.slice(0, 120)}`);
           continue;
         }
+        // **The bundle asks the runtime to emit** (novox/hq ADR 0193): published on the bus as this
+        // module, and answered once the bus has accepted it, so the tool's emit means what it means
+        // in-process. Nothing else a bundle may ask.
+        if (typeof reply.method === "string") {
+          const id = reply.id;
+          const answer = (m: Record<string, unknown>) => proc.stdin!.write(JSON.stringify({ jsonrpc: "2.0", id, ...m }) + "\n");
+          if (reply.method !== "mesh/publish") {
+            if (id !== undefined) answer({ error: { code: -32601, message: `the runtime answers no ${reply.method} from a bundle` } });
+            continue;
+          }
+          atWork.run({ module }, () => broker().publish(reply.params as Envelope<unknown>))
+            .then(() => { if (id !== undefined) answer({ result: {} }); })
+            .catch((err: unknown) => { if (id !== undefined) answer({ error: { code: -32000, message: err instanceof Error ? err.message : String(err) } }); });
+          continue;
+        }
         const waiting = typeof reply.id === "number" ? pending.get(reply.id) : undefined;
         if (!waiting) continue;
-        pending.delete(reply.id!);
+        pending.delete(reply.id as number);
         clearTimeout(waiting.timer);
         if (reply.error) waiting.reject(new Error(reply.error.message ?? "the bundle refused the request"));
         else waiting.resolve(reply.result);
       }
     });
     // stderr is the bundle's log; kept under the module's name so a fault reads where it belongs.
+    // The last thing it said is kept, so a bundle that dies says why in its own words, not by code.
+    let lastSaid = "";
     proc.stderr!.on("data", (chunk: Buffer) => {
-      for (const line of chunk.toString("utf8").split("\n")) if (line.trim()) console.log(`[${module}] ${line}`);
+      for (const line of chunk.toString("utf8").split("\n")) {
+        if (!line.trim()) continue;
+        console.log(`[${module}] ${line}`);
+        if (/\S/.test(line) && !/^\s+at\s/.test(line) && !/^Node\.js v/.test(line)) lastSaid = line.trim();
+      }
     });
     const exited = new Promise<never>((_, reject) => {
       proc.once("error", (err) => reject(err));
       proc.once("exit", (code, signal) => {
-        const why = `${module}'s bundle exited (${signal ?? code})`;
+        const why = `${module}'s bundle exited (${signal ?? code})` + (lastSaid ? `: ${lastSaid}` : "");
         for (const [id, p] of pending) {
           pending.delete(id);
           clearTimeout(p.timer);