diff --git a/e2e/specs/mock/favorite-menu-navigation.spec.ts b/e2e/specs/mock/favorite-menu-navigation.spec.ts
index aad4963a..3270d18d 100644
--- a/e2e/specs/mock/favorite-menu-navigation.spec.ts
+++ b/e2e/specs/mock/favorite-menu-navigation.spec.ts
@@ -57,7 +57,7 @@ test("favorite entry and three-tab Menu navigation render on the real pages", as
     name: "Primary navigation",
   });
   await expect(navigation).toContainText("Chat");
-  await expect(navigation).toContainText("Elio Private Zone");
+  await expect(navigation).toContainText("Private Zone");
   await expect(navigation).toContainText("Menu");
   await savePreview(page, `${mobile ? "mobile" : "desktop"}-splash.png`);
 
@@ -94,8 +94,16 @@ test("favorite entry and three-tab Menu navigation render on the real pages", as
       });
     });
     await page.goto(defaultCharacterChatPath);
-    await expect(page.getByRole("button", { name: "Saved" })).toBeVisible();
-    await savePreview(page, "mobile-ios-external-chat-saved.png");
+    const iosDownload = page.getByRole("button", { name: "Download" });
+    await expect(iosDownload).toBeVisible();
+    await iosDownload.click();
+    await expect(
+      page.getByRole("heading", { name: "Add CozSweet to Home Screen" }),
+    ).toBeVisible();
+    await expect(page.getByRole("dialog")).toContainText(
+      "In Safari, tap the Share button, then choose “Add to Home Screen”.",
+    );
+    await savePreview(page, "mobile-ios-external-chat-download.png");
   }
 
   expect(browserErrors.filter(isFeatureRuntimeError)).toEqual([]);
diff --git a/e2e/specs/mock/paid-image.spec.ts b/e2e/specs/mock/paid-image.spec.ts
index b9f2202c..2a4bdadc 100644
--- a/e2e/specs/mock/paid-image.spec.ts
+++ b/e2e/specs/mock/paid-image.spec.ts
@@ -1,6 +1,8 @@
 import { expect, test } from "@playwright/test";
 
 import { mockCoreApis } from "@e2e/fixtures/api-mocks";
+import { apiEnvelope } from "@e2e/fixtures/data/common";
+import { createPaidImageHistoryResponse } from "@e2e/fixtures/data/chat";
 import {
   paidImageDisplayMessageId,
   paidImageMessageId,
@@ -97,3 +99,38 @@ test("guest can unlock a paid image after email login and subscription payment",
   expect(new URL(page.url()).pathname).toBe(defaultCharacterChatPath);
   await expect(page.getByRole("textbox", { name: "Message" })).toBeVisible();
 });
+
+test("fullscreen image closes from its back button, the image, and browser history Back", async ({
+  page,
+}) => {
+  await page.route("**/api/chat/history**", async (route) => {
+    await route.fulfill({
+      json: apiEnvelope(createPaidImageHistoryResponse(true)),
+    });
+  });
+  await enterChatFromSplash(page);
+  await dismissChatInterruptions(page);
+
+  const imageButton = page.getByRole("button", {
+    name: "Open image in fullscreen",
+  });
+  const imageDialog = page.getByRole("dialog", { name: "Fullscreen image" });
+
+  await imageButton.click();
+  await expect(imageDialog).toBeVisible();
+  await imageDialog.getByRole("button", { name: "Back" }).click();
+  await expect(imageDialog).toHaveCount(0);
+  await expect(page).toHaveURL(defaultCharacterChatPath);
+
+  await imageButton.click();
+  await expect(imageDialog).toBeVisible();
+  await imageDialog.locator("img").click();
+  await expect(imageDialog).toHaveCount(0);
+  await expect(page).toHaveURL(defaultCharacterChatPath);
+
+  await imageButton.click();
+  await expect(imageDialog).toBeVisible();
+  await page.goBack();
+  await expect(imageDialog).toHaveCount(0);
+  await expect(page).toHaveURL(defaultCharacterChatPath);
+});
diff --git a/src/app/_components/core/__tests__/favorite-entry-button.test.tsx b/src/app/_components/core/__tests__/favorite-entry-button.test.tsx
new file mode 100644
index 00000000..8340acf3
--- /dev/null
+++ b/src/app/_components/core/__tests__/favorite-entry-button.test.tsx
@@ -0,0 +1,80 @@
+/* @vitest-environment jsdom */
+
+import { act } from "react";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { BrowserDetector } from "@/utils/browser-detect";
+import { PlatformDetector } from "@/utils/platform-detect";
+import { pwaUtil } from "@/utils/pwa";
+
+import { FavoriteEntryButton } from "../favorite-entry-button";
+
+describe("FavoriteEntryButton install flow", () => {
+  let container: HTMLDivElement;
+  let root: Root;
+
+  beforeEach(() => {
+    (globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean })
+      .IS_REACT_ACT_ENVIRONMENT = true;
+    window.localStorage.setItem("cozsweet:favorite_entry", "1");
+    vi.spyOn(BrowserDetector, "isInAppBrowser").mockReturnValue(false);
+    vi.spyOn(pwaUtil, "isInstalled").mockReturnValue(false);
+    vi.spyOn(pwaUtil, "prepareInstallPrompt").mockImplementation(() => undefined);
+    vi.spyOn(pwaUtil, "subscribe").mockReturnValue(() => undefined);
+    container = document.createElement("div");
+    document.body.append(container);
+    root = createRoot(container);
+  });
+
+  afterEach(() => {
+    act(() => root.unmount());
+    container.remove();
+    window.localStorage.clear();
+    vi.restoreAllMocks();
+  });
+
+  it("shows Download on iOS and opens Safari add-to-home instructions", () => {
+    vi.spyOn(PlatformDetector, "isIOS").mockReturnValue(true);
+    vi.spyOn(PlatformDetector, "isAndroid").mockReturnValue(false);
+
+    renderButton();
+    const downloadButton = getButton("Download");
+    act(() => downloadButton.click());
+
+    expect(container.querySelector('[role="dialog"]')).not.toBeNull();
+    expect(container.textContent).toContain("Add CozSweet to Home Screen");
+    expect(container.textContent).toContain(
+      "In Safari, tap the Share button, then choose “Add to Home Screen”.",
+    );
+  });
+
+  it("opens the native Android install prompt and marks an accepted install as Saved", async () => {
+    vi.spyOn(PlatformDetector, "isIOS").mockReturnValue(false);
+    vi.spyOn(PlatformDetector, "isAndroid").mockReturnValue(true);
+    const install = vi.spyOn(pwaUtil, "install").mockResolvedValue("accepted");
+
+    renderButton();
+    await act(async () => {
+      getButton("Download").click();
+      await Promise.resolve();
+    });
+
+    expect(install).toHaveBeenCalledTimes(1);
+    expect(getButton("Saved")).not.toBeNull();
+  });
+
+  function renderButton(): void {
+    act(() => {
+      root.render(<FavoriteEntryButton characterSlug="elio" />);
+    });
+  }
+
+  function getButton(label: string): HTMLButtonElement {
+    const button = container.querySelector<HTMLButtonElement>(
+      `button[aria-label="${label}"]`,
+    );
+    if (!button) throw new Error(`Missing button: ${label}`);
+    return button;
+  }
+});
diff --git a/src/app/_components/core/favorite-entry-button.module.css b/src/app/_components/core/favorite-entry-button.module.css
index 6aeb012f..da489b2b 100644
--- a/src/app/_components/core/favorite-entry-button.module.css
+++ b/src/app/_components/core/favorite-entry-button.module.css
@@ -78,19 +78,98 @@
   outline-color: #f84d96;
 }
 
-.hint {
-  position: absolute;
-  top: calc(100% + 8px);
-  right: 0;
-  z-index: 45;
-  width: max-content;
-  max-width: min(72vw, 250px);
-  padding: 8px 10px;
-  border-radius: 10px;
-  background: rgba(22, 18, 25, 0.94);
-  color: #ffffff;
-  font-size: 11px;
-  font-weight: 700;
-  line-height: 1.3;
-  box-shadow: 0 10px 26px rgba(0, 0, 0, 0.24);
+.guideBackdrop {
+  position: fixed;
+  inset: 0;
+  z-index: 240;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding:
+    calc(18px + var(--app-safe-top, 0px))
+    calc(18px + var(--app-safe-right, 0px))
+    calc(18px + var(--app-safe-bottom, 0px))
+    calc(18px + var(--app-safe-left, 0px));
+  background: rgba(15, 11, 18, 0.58);
+  backdrop-filter: blur(4px);
+}
+
+.guideDialog {
+  position: relative;
+  display: flex;
+  width: min(100%, 340px);
+  flex-direction: column;
+  align-items: center;
+  padding: 28px 22px 20px;
+  border: 1px solid rgba(255, 255, 255, 0.72);
+  border-radius: 28px;
+  background: rgba(255, 250, 252, 0.98);
+  box-shadow: 0 24px 70px rgba(33, 17, 26, 0.3);
+  color: #2d2026;
+  text-align: center;
+}
+
+.guideClose {
+  position: absolute;
+  top: 12px;
+  right: 12px;
+  display: inline-flex;
+  width: 36px;
+  height: 36px;
+  align-items: center;
+  justify-content: center;
+  border: 0;
+  border-radius: 999px;
+  background: rgba(45, 32, 38, 0.07);
+  color: #5b4a52;
+  cursor: pointer;
+}
+
+.guideIcon {
+  display: inline-flex;
+  width: 58px;
+  height: 58px;
+  align-items: center;
+  justify-content: center;
+  margin-bottom: 14px;
+  border-radius: 19px;
+  background: linear-gradient(135deg, #ff82b2, #f84d96);
+  box-shadow: 0 12px 26px rgba(248, 77, 150, 0.26);
+  color: #ffffff;
+}
+
+.guideDialog h2 {
+  margin: 0;
+  color: #281a21;
+  font-size: 21px;
+  font-weight: 850;
+  line-height: 1.2;
+}
+
+.guideDialog p {
+  margin: 12px 0 20px;
+  color: #685761;
+  font-size: 15px;
+  font-weight: 650;
+  line-height: 1.5;
+}
+
+.guideConfirm {
+  width: 100%;
+  min-height: 46px;
+  border: 0;
+  border-radius: 999px;
+  background: linear-gradient(135deg, #ff76ab, #f84d96);
+  box-shadow: 0 10px 24px rgba(248, 77, 150, 0.24);
+  color: #ffffff;
+  cursor: pointer;
+  font: inherit;
+  font-size: 16px;
+  font-weight: 850;
+}
+
+.guideClose:focus-visible,
+.guideConfirm:focus-visible {
+  outline: 2px solid #f84d96;
+  outline-offset: 3px;
 }
diff --git a/src/app/_components/core/favorite-entry-button.tsx b/src/app/_components/core/favorite-entry-button.tsx
index d8585669..787ed135 100644
--- a/src/app/_components/core/favorite-entry-button.tsx
+++ b/src/app/_components/core/favorite-entry-button.tsx
@@ -1,7 +1,7 @@
 "use client";
 
-import { useEffect, useState } from "react";
-import { Download, Star } from "lucide-react";
+import { useEffect, useId, useState } from "react";
+import { Download, Share2, Star, X } from "lucide-react";
 
 import { openChatInExternalBrowser } from "@/lib/chat/chat_external_browser";
 import {
@@ -25,7 +25,10 @@ export function FavoriteEntryButton({
   tone = "dark",
 }: FavoriteEntryButtonProps) {
   const [mode, setMode] = useState<FavoriteEntryMode>("favorite");
-  const [installHint, setInstallHint] = useState(false);
+  const [installGuide, setInstallGuide] = useState<
+    "ios" | "browser" | null
+  >(null);
+  const installGuideTitleId = useId();
 
   useEffect(() => {
     const updateMode = () => {
@@ -46,6 +49,15 @@ export function FavoriteEntryButton({
     return unsubscribe;
   }, []);
 
+  useEffect(() => {
+    if (!installGuide) return;
+    const handleKeyDown = (event: KeyboardEvent) => {
+      if (event.key === "Escape") setInstallGuide(null);
+    };
+    document.addEventListener("keydown", handleKeyDown);
+    return () => document.removeEventListener("keydown", handleKeyDown);
+  }, [installGuide]);
+
   const handleClick = async (): Promise<void> => {
     if (mode === "favorite") {
       await openChatInExternalBrowser({ characterSlug });
@@ -53,14 +65,18 @@ export function FavoriteEntryButton({
     }
 
     if (mode === "download") {
+      if (PlatformDetector.isIOS()) {
+        setInstallGuide("ios");
+        return;
+      }
       pwaUtil.prepareInstallPrompt();
       const result = await pwaUtil.install();
       if (result === "accepted" || pwaUtil.isInstalled()) {
         setMode("saved");
-        setInstallHint(false);
+        setInstallGuide(null);
         return;
       }
-      if (result === "unavailable") setInstallHint(true);
+      if (result === "unavailable") setInstallGuide("browser");
     }
   };
 
@@ -91,10 +107,49 @@ export function FavoriteEntryButton({
         )}
         {mode === "favorite" ? null : <span>{label}</span>}
       </button>
-      {installHint ? (
-        <span className={styles.hint} role="status">
-          Chrome menu → Add to Home screen
-        </span>
+      {installGuide ? (
+        <div
+          className={styles.guideBackdrop}
+          onClick={() => setInstallGuide(null)}
+          role="presentation"
+        >
+          <section
+            className={styles.guideDialog}
+            role="dialog"
+            aria-modal="true"
+            aria-labelledby={installGuideTitleId}
+            onClick={(event) => event.stopPropagation()}
+          >
+            <button
+              type="button"
+              className={styles.guideClose}
+              onClick={() => setInstallGuide(null)}
+              aria-label="Close install instructions"
+            >
+              <X size={18} aria-hidden="true" />
+            </button>
+            <span className={styles.guideIcon} aria-hidden="true">
+              {installGuide === "ios" ? (
+                <Share2 size={28} strokeWidth={2.2} />
+              ) : (
+                <Download size={28} strokeWidth={2.2} />
+              )}
+            </span>
+            <h2 id={installGuideTitleId}>Add CozSweet to Home Screen</h2>
+            <p>
+              {installGuide === "ios"
+                ? "In Safari, tap the Share button, then choose “Add to Home Screen”."
+                : "Open your browser menu, then choose “Add to Home screen”."}
+            </p>
+            <button
+              type="button"
+              className={styles.guideConfirm}
+              onClick={() => setInstallGuide(null)}
+            >
+              Got it
+            </button>
+          </section>
+        </div>
       ) : null}
     </div>
   );
diff --git a/src/app/chat/chat-screen.tsx b/src/app/chat/chat-screen.tsx
index 8654e3c3..975038fd 100644
--- a/src/app/chat/chat-screen.tsx
+++ b/src/app/chat/chat-screen.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useEffect, useMemo, type CSSProperties } from "react";
+import { useEffect, useMemo, useRef, type CSSProperties } from "react";
 import Image from "next/image";
 import { useRouter, useSearchParams } from "next/navigation";
 
@@ -70,6 +70,8 @@ export function ChatScreen() {
   const chatDispatch = useChatDispatch();
   const authState = useAuthState();
   const authDispatch = useAuthDispatch();
+  const imageOpenedFromChatRef = useRef(false);
+  const imageViewerClosingRef = useRef(false);
   useSplashLatestMessageSync({
     characterId: state.characterId,
     historyLoaded: state.historyLoaded,
@@ -127,6 +129,13 @@ export function ChatScreen() {
     loginStatus: authState.loginStatus,
   });
 
+  useEffect(() => {
+    if (!imageMessageId) {
+      imageOpenedFromChatRef.current = false;
+      imageViewerClosingRef.current = false;
+    }
+  }, [imageMessageId]);
+
   useEffect(() => {
     if (
       !imageMessageId ||
@@ -218,6 +227,7 @@ export function ChatScreen() {
   }
 
   function handleOpenImage(displayMessageId: string): void {
+    imageOpenedFromChatRef.current = true;
     router.push(
       buildChatImageOverlayUrl(displayMessageId, characterRoutes.chat),
       { scroll: false },
@@ -225,6 +235,13 @@ export function ChatScreen() {
   }
 
   function handleCloseImageViewer(): void {
+    if (imageViewerClosingRef.current) return;
+    imageViewerClosingRef.current = true;
+    if (imageOpenedFromChatRef.current) {
+      imageOpenedFromChatRef.current = false;
+      router.back();
+      return;
+    }
     router.replace(
       buildChatWithoutImageOverlayUrl(searchParams, characterRoutes.chat),
       { scroll: false },
diff --git a/src/app/chat/components/__tests__/fullscreen-image-viewer.test.tsx b/src/app/chat/components/__tests__/fullscreen-image-viewer.test.tsx
new file mode 100644
index 00000000..52db81c0
--- /dev/null
+++ b/src/app/chat/components/__tests__/fullscreen-image-viewer.test.tsx
@@ -0,0 +1,80 @@
+/* @vitest-environment jsdom */
+
+import { act } from "react";
+import { createRoot, type Root } from "react-dom/client";
+import {
+  afterEach,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  type Mock,
+  vi,
+} from "vitest";
+
+import { FullscreenImageViewer } from "../fullscreen-image-viewer";
+
+describe("FullscreenImageViewer", () => {
+  let container: HTMLDivElement;
+  let root: Root;
+  let onClose: Mock<() => void>;
+
+  beforeEach(() => {
+    (globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean })
+      .IS_REACT_ACT_ENVIRONMENT = true;
+    container = document.createElement("div");
+    document.body.append(container);
+    root = createRoot(container);
+    onClose = vi.fn<() => void>();
+
+    act(() => {
+      root.render(
+        <FullscreenImageViewer
+          characterId="elio-silvestri"
+          remoteMessageId="message-1"
+          imageUrl="/chat-image.png"
+          onClose={onClose}
+        />,
+      );
+    });
+  });
+
+  afterEach(() => {
+    act(() => root.unmount());
+    container.remove();
+  });
+
+  it("closes exactly once when the fullscreen image is tapped", () => {
+    const image = container.querySelector("img");
+    expect(image).not.toBeNull();
+
+    act(() => image?.click());
+
+    expect(onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it("closes exactly once from the visible back button", () => {
+    const backButton = container.querySelector<HTMLButtonElement>(
+      'button[aria-label="Back"]',
+    );
+    expect(backButton).not.toBeNull();
+
+    act(() => backButton?.click());
+
+    expect(onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it("closes from the backdrop and Escape key", () => {
+    const viewer = container.querySelector<HTMLDivElement>(
+      '[aria-label="Fullscreen image"]',
+    );
+    expect(viewer).not.toBeNull();
+
+    act(() => viewer?.click());
+    act(() =>
+      document.dispatchEvent(new KeyboardEvent("keydown", { key: "Escape" })),
+    );
+
+    expect(onClose).toHaveBeenCalledTimes(2);
+  });
+});
diff --git a/src/app/chat/components/first-recharge-offer-banner.module.css b/src/app/chat/components/first-recharge-offer-banner.module.css
index 20fc2f46..16c71b6c 100644
--- a/src/app/chat/components/first-recharge-offer-banner.module.css
+++ b/src/app/chat/components/first-recharge-offer-banner.module.css
@@ -123,13 +123,14 @@
 
 .compactButton {
   display: grid;
+  width: min(100%, 240px);
   min-width: 0;
-  max-width: 224px;
-  min-height: 44px;
+  max-width: 240px;
+  min-height: 50px;
   grid-template-columns: auto minmax(0, 1fr) auto;
   align-items: center;
-  gap: 7px;
-  padding: 5px 8px;
+  gap: 8px;
+  padding: 7px 10px;
   overflow: hidden;
   border: 1px solid rgba(255, 255, 255, 0.42);
   border-radius: 16px;
@@ -146,8 +147,8 @@
 
 .compactIcon {
   display: inline-flex;
-  width: 28px;
-  height: 28px;
+  width: 32px;
+  height: 32px;
   align-items: center;
   justify-content: center;
   border-radius: 10px;
@@ -160,7 +161,7 @@
   min-width: 0;
   flex-direction: column;
   gap: 2px;
-  font-size: 10px;
+  font-size: 11px;
   font-weight: 800;
   line-height: 1.05;
   text-transform: uppercase;
@@ -180,7 +181,7 @@
 
 .compactCopy strong {
   color: #ec006d;
-  font-size: 15px;
+  font-size: 17px;
   font-weight: 950;
   letter-spacing: -0.02em;
 }
diff --git a/src/app/chat/components/fullscreen-image-viewer.tsx b/src/app/chat/components/fullscreen-image-viewer.tsx
index bc1f236f..43143e27 100644
--- a/src/app/chat/components/fullscreen-image-viewer.tsx
+++ b/src/app/chat/components/fullscreen-image-viewer.tsx
@@ -10,7 +10,7 @@
  *   - 双指缩放（CSS `touch-action: pinch-zoom`）
  */
 import { ChevronLeft } from "lucide-react";
-import { useEffect } from "react";
+import { useEffect, type MouseEvent } from "react";
 
 import { BackButton } from "@/app/_components";
 
@@ -44,6 +44,10 @@ export function FullscreenImageViewer({
     return () => document.removeEventListener("keydown", handleKey);
   }, [onClose]);
 
+  const handleBackdropClick = (event: MouseEvent<HTMLDivElement>) => {
+    if (event.target === event.currentTarget) onClose();
+  };
+
   if (imagePaywalled) {
     return (
       <div
@@ -90,7 +94,7 @@ export function FullscreenImageViewer({
   return (
     <div
       className={styles.viewer}
-      onClick={onClose}
+      onClick={handleBackdropClick}
       role="dialog"
       aria-modal="true"
       aria-label="Fullscreen image"
@@ -110,7 +114,7 @@ export function FullscreenImageViewer({
         errorClassName="error"
         width={800}
         height={800}
-        onClick={(event) => event.stopPropagation()}
+        onClick={onClose}
       />
     </div>
   );
diff --git a/src/lib/navigation/__tests__/favorite_entry.test.ts b/src/lib/navigation/__tests__/favorite_entry.test.ts
index 726c39a8..d33c7d52 100644
--- a/src/lib/navigation/__tests__/favorite_entry.test.ts
+++ b/src/lib/navigation/__tests__/favorite_entry.test.ts
@@ -30,7 +30,7 @@ describe("favorite external entry", () => {
     ).toBe("download");
   });
 
-  it("turns the external iOS action into Saved", () => {
+  it("turns the external iOS action into Download until standalone mode is detected", () => {
     expect(
       resolveFavoriteEntryMode({
         hasFavoriteIntent: true,
@@ -39,7 +39,7 @@ describe("favorite external entry", () => {
         isInAppBrowser: false,
         isInstalled: false,
       }),
-    ).toBe("saved");
+    ).toBe("download");
   });
 
   it("treats an installed PWA as saved", () => {
diff --git a/src/lib/navigation/favorite_entry.ts b/src/lib/navigation/favorite_entry.ts
index 49b298f2..b3956289 100644
--- a/src/lib/navigation/favorite_entry.ts
+++ b/src/lib/navigation/favorite_entry.ts
@@ -26,7 +26,7 @@ export function resolveFavoriteEntryMode({
   if (isInstalled) return "saved";
   if (!hasFavoriteIntent) return "favorite";
   if (isAndroid) return "download";
-  if (isIOS) return "saved";
+  if (isIOS) return "download";
   return "saved";
 }