A module's state through the runtime, in TypeScript and Go (novox/hq ADR 0201)

state(name) / stdio.State(name): get, put, delete, keys and watch over the
runtime's mesh/state verbs. A watch's handler is registered under the id it
is asked with, so its current values — which arrive before the watch is
answered — and its changes reach it and no other watch.

test/fixtures/stdio-state.mjs

@@ -0,0 +1,18 @@
+// A launched bundle that keeps state through its runtime (novox/hq ADR 0201): it watches its servers as
+// it is imported, before it says what it serves, and its tools write, read and list them.
+import { state } from "../../dist/state/index.js";
+import { registerModuleTools } from "../../dist/tools/index.js";
+import { serveRegisteredOverStdio } from "../../dist/stdio/index.js";
+
+const servers = state("servers");
+await servers.watch((c) => {
+  process.stderr.write(`${c.current ? "was" : "now"} ${c.op} ${c.key} ${JSON.stringify(c.value ?? null)}\n`);
+  if (c.value && c.value.fail) throw new Error("not this one");
+});
+process.stderr.write("watching\n");
+registerModuleTools("keeper", () => [
+  { name: "remember", description: "put", input: {}, run: async (a) => servers.put(a.key, a.value) },
+  { name: "recall", description: "get", input: {}, run: async (a) => servers.get(a.key) },
+  { name: "list", description: "keys", input: {}, run: async () => state("licence-manager.bindings").keys() },
+]);
+await serveRegisteredOverStdio();