refactor(subscription): tighten payment flow boundaries

src/lib/navigation/__tests__/subscription_exit.test.ts

@@ -0,0 +1,48 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+import { ROUTES } from "@/router/routes";
+
+import { consumePendingChatImageReturn } from "../chat_image_return_session";
+import {
+  consumeSubscriptionExitUrl,
+  consumeSubscriptionExplicitExitUrl,
+  getSubscriptionFallbackExitUrl,
+} from "../subscription_exit";
+
+vi.mock("../chat_image_return_session", () => ({
+  consumePendingChatImageReturn: vi.fn(),
+}));
+
+const consumePendingChatImageReturnMock = vi.mocked(
+  consumePendingChatImageReturn,
+);
+
+describe("subscription exit helpers", () => {
+  beforeEach(() => {
+    consumePendingChatImageReturnMock.mockReset();
+  });
+
+  it("uses explicit chat image return urls first", () => {
+    consumePendingChatImageReturnMock.mockReturnValue({
+      reason: "image_paywall",
+      messageId: "msg_1",
+      returnUrl: "/chat/image/msg_1",
+      createdAt: 1,
+    });
+
+    expect(consumeSubscriptionExplicitExitUrl()).toBe("/chat/image/msg_1");
+  });
+
+  it("falls back to chat when requested", () => {
+    consumePendingChatImageReturnMock.mockReturnValue(null);
+
+    expect(consumeSubscriptionExitUrl("chat")).toBe(ROUTES.chat);
+  });
+
+  it("falls back to sidebar by default", () => {
+    consumePendingChatImageReturnMock.mockReturnValue(null);
+
+    expect(getSubscriptionFallbackExitUrl(null)).toBe(ROUTES.sidebar);
+    expect(consumeSubscriptionExitUrl(null)).toBe(ROUTES.sidebar);
+  });
+});

src/lib/navigation/subscription_exit.ts

@@ -0,0 +1,28 @@
+"use client";
+
+import { ROUTES } from "@/router/routes";
+
+import { consumePendingChatImageReturn } from "./chat_image_return_session";
+
+export type SubscriptionReturnTo = "chat" | null;
+
+export function consumeSubscriptionExplicitExitUrl(): string | null {
+  const pendingImageReturn = consumePendingChatImageReturn();
+  if (pendingImageReturn) return pendingImageReturn.returnUrl;
+  return null;
+}
+
+export function getSubscriptionFallbackExitUrl(
+  returnTo: SubscriptionReturnTo,
+): string {
+  return returnTo === "chat" ? ROUTES.chat : ROUTES.sidebar;
+}
+
+export function consumeSubscriptionExitUrl(
+  returnTo: SubscriptionReturnTo,
+): string {
+  return (
+    consumeSubscriptionExplicitExitUrl() ??
+    getSubscriptionFallbackExitUrl(returnTo)
+  );
+}