tools: serve each tool on its own module-namespaced key (ADR 0052)

serveTools now serves each tool on serve.<module>.<tool> instead of one
tools.invoke that dispatched by name — so a module's account is scoped to
serve.<module>.* and one module cannot answer another's calls. toolKey and
invokeTool are the caller's side. A tool name need only be unique within its
module now, not across the mesh.

src/tools/index.ts

@@ -66,20 +66,43 @@ export function listTools(env: NodeJS.ProcessEnv = process.env): { module: strin
  * other — two tools answering one name is a fault, not a race to resolve.
  */
 export async function serveTools(broker: Broker, env: NodeJS.ProcessEnv = process.env): Promise<() => void> {
-  const byName = new Map<string, ToolDefinition>();
+  // Each tool is served on its own key, namespaced by its module (novox/hq ADR 0052): a caller
+  // invokes `<module>.<tool>`, only the module that serves it answers, and the module's account is
+  // scoped to serve.<module>.* — so one module cannot answer another's calls. The module is the
+  // namespace, so a tool name need only be unique within its module, not across the whole mesh.
+  const stops: Array<() => void> = [];
   for (const { module, tools } of collectTools(env)) {
+    const seen = new Set<string>();
     for (const t of tools) {
-      if (byName.has(t.name)) {
-        throw new Error(`tool name ${t.name} is exposed by two modules (one is ${module}) — refused`);
+      if (seen.has(t.name)) {
+        throw new Error(`${module} exposes two tools named ${t.name} — refused`);
       }
-      byName.set(t.name, t);
+      seen.add(t.name);
+      const stop = await broker.handle<Readonly<Record<string, unknown>>, unknown>(
+        toolKey(module, t.name),
+        (args) => t.run(args ?? {}),
+      );
+      stops.push(stop);
     }
   }
-  return broker.handle<Invocation, unknown>("tools.invoke", async (inv) => {
-    const tool = byName.get(inv.tool);
-    if (!tool) throw new Error(`no such tool: ${inv.tool}`);
-    return tool.run(inv.args ?? {});
-  });
+  return () => {
+    for (const stop of stops) stop();
+  };
+}
+
+/** The broker key a tool is served on and invoked by — the module namespaces the tool (ADR 0052). */
+export function toolKey(module: string, tool: string): string {
+  return `${module}.${tool}`;
+}
+
+/** Invoke a module's tool over the broker — the caller's side of serving. */
+export async function invokeTool(
+  broker: Broker,
+  module: string,
+  tool: string,
+  args: Readonly<Record<string, unknown>> = {},
+): Promise<unknown> {
+  return broker.request(toolKey(module, tool), args);
 }
 
 /** Testing/inspection: drop all registrations. */