feat: initialize LineUp Tauri reference host

tauri/src/protocol.ts

@@ -0,0 +1,60 @@
+export const LINEUP_PROTOCOL_VERSION = 1;
+
+export type Envelope = {
+  v: number;
+  id?: string;
+  type: string;
+  conversation_id?: string;
+  payload?: unknown;
+};
+
+export type ConversationItem =
+  | { kind: "markdown"; markdown: string; envelope?: Envelope }
+  | { kind: "agent-status"; status: string; detail: string; envelope?: Envelope }
+  | { kind: "progress"; title: string; percent: number; status: string; envelope?: Envelope }
+  | { kind: "error"; message: string; envelope?: Envelope }
+  | { kind: "surface"; envelope: Envelope }
+  | { kind: "app-call"; envelope: Envelope }
+  | { kind: "fallback"; reason: string; envelope?: Envelope };
+
+function object(value: unknown): Record<string, unknown> | null {
+  return value !== null && typeof value === "object" && !Array.isArray(value)
+    ? (value as Record<string, unknown>)
+    : null;
+}
+
+function text(value: unknown): string {
+  return typeof value === "string" ? value : "";
+}
+
+export function decodeConversationItem(raw: string): ConversationItem {
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(raw);
+  } catch {
+    return { kind: "markdown", markdown: raw };
+  }
+  const envelope = object(parsed) as Envelope | null;
+  if (!envelope || envelope.v !== LINEUP_PROTOCOL_VERSION || !envelope.type?.startsWith("lineup.v1.")) {
+    return { kind: "fallback", reason: "invalid_envelope" };
+  }
+  const payload = object(envelope.payload) ?? {};
+  switch (envelope.type) {
+    case "lineup.v1.text":
+      return { kind: "markdown", markdown: text(payload.markdown) || text(payload.text), envelope };
+    case "lineup.v1.agent.status":
+      return { kind: "agent-status", status: text(payload.status), detail: text(payload.detail), envelope };
+    case "lineup.v1.agent.progress":
+      return { kind: "progress", title: text(payload.title), percent: Number(payload.percent) || 0, status: text(payload.status), envelope };
+    case "lineup.v1.error":
+      return { kind: "error", message: text(payload.message) || "Agent 执行失败", envelope };
+    case "lineup.v1.ui.open":
+    case "lineup.v1.ui.patch":
+    case "lineup.v1.ui.close":
+      return { kind: "surface", envelope };
+    case "lineup.v1.app.call":
+      return { kind: "app-call", envelope };
+    default:
+      return { kind: "fallback", reason: "unsupported_type", envelope };
+  }
+}