From 6d5a2570d448a079d6fd8d23f5e966112118790a Mon Sep 17 00:00:00 2001
From: adlee-was-taken <aaron.daniel.lee@gmail.com>
Date: Sat, 2 May 2026 17:16:21 -0400
Subject: [PATCH] feat(relay): in-memory queue with consume-once semantics

---
 tools/relay/queue.test.ts | 58 +++++++++++++++++++++++++++++++++++++++
 tools/relay/queue.ts      | 55 +++++++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 tools/relay/queue.test.ts
 create mode 100644 tools/relay/queue.ts

diff --git a/tools/relay/queue.test.ts b/tools/relay/queue.test.ts
new file mode 100644
index 0000000..892da0b
--- /dev/null
+++ b/tools/relay/queue.test.ts
@@ -0,0 +1,58 @@
+import { describe, it, beforeEach } from "node:test";
+import assert from "node:assert/strict";
+import { RelayQueue, isRole } from "./queue.ts";
+
+describe("RelayQueue", () => {
+  let q: RelayQueue;
+
+  beforeEach(() => {
+    q = new RelayQueue();
+  });
+
+  it("post + read roundtrip returns the message with correct fields", () => {
+    q.post("dev-b", "pm", "status", "Task P4 DONE");
+    const msgs = q.read("pm");
+    assert.equal(msgs.length, 1);
+    assert.equal(msgs[0].from, "dev-b");
+    assert.equal(msgs[0].to, "pm");
+    assert.equal(msgs[0].kind, "status");
+    assert.equal(msgs[0].body, "Task P4 DONE");
+    assert.ok(typeof msgs[0].id === "string" && msgs[0].id.length > 0);
+    assert.ok(typeof msgs[0].ts === "string");
+  });
+
+  it("consume-once: second read returns empty", () => {
+    q.post("dev-a", "pm", "question", "Should I use approach A?");
+    q.read("pm");
+    const second = q.read("pm");
+    assert.deepEqual(second, []);
+  });
+
+  it("list_pending does not drain inbox", () => {
+    q.post("dev-b", "pm", "directive", "PROCEED");
+    const before = q.pending("pm");
+    assert.equal(before.count, 1);
+    const after = q.read("pm");
+    assert.equal(after.length, 1);
+  });
+
+  it("FIFO ordering across multiple senders", () => {
+    q.post("dev-a", "pm", "status", "first");
+    q.post("dev-b", "pm", "status", "second");
+    q.post("dev-a", "pm", "question", "third");
+    const msgs = q.read("pm");
+    assert.equal(msgs.length, 3);
+    assert.equal(msgs[0].body, "first");
+    assert.equal(msgs[1].body, "second");
+    assert.equal(msgs[2].body, "third");
+  });
+
+  it("isRole rejects unknown strings", () => {
+    assert.ok(isRole("pm"));
+    assert.ok(isRole("dev-a"));
+    assert.ok(isRole("dev-b"));
+    assert.ok(!isRole("dev-c"));
+    assert.ok(!isRole(""));
+    assert.ok(!isRole("PM"));
+  });
+});
diff --git a/tools/relay/queue.ts b/tools/relay/queue.ts
new file mode 100644
index 0000000..da7fede
--- /dev/null
+++ b/tools/relay/queue.ts
@@ -0,0 +1,55 @@
+import { randomUUID } from "node:crypto";
+
+export type Role = "pm" | "dev-a" | "dev-b";
+export type MessageKind = "status" | "question" | "directive" | "free";
+
+export interface RelayMessage {
+  id: string;
+  from: Role;
+  to: Role;
+  kind: MessageKind;
+  body: string;
+  ts: string;
+}
+
+const KNOWN_ROLES = new Set<string>(["pm", "dev-a", "dev-b"]);
+
+export function isRole(s: string): s is Role {
+  return KNOWN_ROLES.has(s);
+}
+
+export class RelayQueue {
+  private readonly queues = new Map<Role, RelayMessage[]>([
+    ["pm", []],
+    ["dev-a", []],
+    ["dev-b", []],
+  ]);
+
+  post(from: Role, to: Role, kind: MessageKind, body: string): RelayMessage {
+    const msg: RelayMessage = {
+      id: randomUUID(),
+      from,
+      to,
+      kind,
+      body,
+      ts: new Date().toISOString(),
+    };
+    this.queues.get(to)!.push(msg);
+    return msg;
+  }
+
+  read(forRole: Role): RelayMessage[] {
+    const inbox = this.queues.get(forRole)!;
+    const messages = [...inbox];
+    inbox.length = 0;
+    return messages;
+  }
+
+  pending(forRole: Role): { count: number; kinds: MessageKind[] } {
+    const inbox = this.queues.get(forRole)!;
+    return {
+      count: inbox.length,
+      kinds: inbox.map((m) => m.kind),
+    };
+  }
+}