1 files changed, 45 insertions, 0 deletions
diff --git a/src/features/surface-host/logic/message-queue.ts b/src/features/surface-host/logic/message-queue.ts
new file mode 100644
index 0000000..a8e1567
--- /dev/null
+++ b/src/features/surface-host/logic/message-queue.ts
@@ -0,0 +1,45 @@
+import type { QueuedMessage } from "@dispatch/wire";
+
+/**
+ * Pure parser for the `rendererId: "message-queue"` custom-field payload.
+ *
+ * The message-queue extension's per-conversation surface emits ONE `custom`
+ * field with `rendererId: "message-queue"` and `payload: QueuePayload`
+ * (`{ messages: QueuedMessage[] }` — the current queue snapshot). This parser
+ * validates the untyped `payload: unknown` at the network seam so a
+ * hostile/partial payload can never crash the renderer (graceful skip → null).
+ *
+ * Empty `messages` is a valid, parseable state (the queue is empty — nothing to
+ * render); the caller hides the panel. Null is returned only for a malformed
+ * payload shape.
+ */
+export interface MessageQueueData {
+	readonly messages: readonly QueuedMessage[];
+}
+
+function isQueuedMessage(v: unknown): v is QueuedMessage {
+	if (typeof v !== "object" || v === null) return false;
+	const o = v as Record<string, unknown>;
+	return (
+		typeof o.id === "string" &&
+		typeof o.text === "string" &&
+		typeof o.queuedAt === "number" &&
+		Number.isFinite(o.queuedAt)
+	);
+}
+
+export function parseMessageQueuePayload(payload: unknown): MessageQueueData | null {
+	if (typeof payload !== "object" || payload === null) return null;
+	const obj = payload as Record<string, unknown>;
+	const raw = obj.messages;
+	if (!Array.isArray(raw)) return null;
+	const messages: QueuedMessage[] = [];
+	for (const entry of raw) {
+		if (!isQueuedMessage(entry)) return null;
+		messages.push(entry);
+	}
+	return { messages };
+}
+
+/** The `rendererId` the message-queue extension's `custom` surface field uses. */
+export const MESSAGE_QUEUE_RENDERER_ID = "message-queue";