diff --git a/frontend/src/App.jsx b/frontend/src/App.jsx
index 68dbd3f95..4f2fa7f61 100644
--- a/frontend/src/App.jsx
+++ b/frontend/src/App.jsx
@@ -8,6 +8,7 @@ import { setupQueries } from './hooks/queries.js'
 import { queryClient, persistOptions } from './queryClient.js'
 import { shellReload } from './lib/shellReloadState.js'
 import { beginEmbedBootstrap } from './lib/chatEmbedBootstrap.js'
+import { startInstallPromptCapture } from './lib/installPrompt.js'
 
 // These flows are mutually exclusive. Keep setup, login, the full shell, and
 // the opaque embed out of one another's startup path; first boot should not
@@ -38,6 +39,10 @@ const EMBED_ROUTE = isEmbedRoute()
 if (EMBED_ROUTE) {
   beginEphemeralAuth()
   beginEmbedBootstrap()
+} else {
+  // Capture Chromium's one-shot install event before setup or sign-in can keep
+  // the first-use shell card from mounting.
+  startInstallPromptCapture()
 }
 
 // Validate a ?return= target: same-origin in-app path only. Rejects
diff --git a/frontend/src/components/ChatView/__tests__/accessibilityHardening.test.js b/frontend/src/components/ChatView/__tests__/accessibilityHardening.test.js
index 3d7cb838d..60485cdbb 100644
--- a/frontend/src/components/ChatView/__tests__/accessibilityHardening.test.js
+++ b/frontend/src/components/ChatView/__tests__/accessibilityHardening.test.js
@@ -45,6 +45,9 @@ test('first-use guidance is a labeled non-modal region with a dismiss action', (
   assert.match(source, /role="region"/)
   assert.match(source, /aria-labelledby="wt-title"/)
   assert.match(source, /aria-label="Dismiss welcome"/)
+  assert.match(source, /aria-labelledby="wt-install-title"/)
+  assert.match(source, /aria-expanded=/)
+  assert.match(source, /role="status"/)
   assert.doesNotMatch(source, /aria-modal="true"/)
 })
 
diff --git a/frontend/src/components/Shell/Shell.css b/frontend/src/components/Shell/Shell.css
index b7c0dde13..374697b95 100644
--- a/frontend/src/components/Shell/Shell.css
+++ b/frontend/src/components/Shell/Shell.css
@@ -424,11 +424,10 @@
 
 /* The install affordance lives in the first-sign-in walkthrough now
    (see frontend/src/components/Walkthrough/WalkthroughOverlay.jsx).
-   beforeinstallprompt capture and the drawer banner that used to
-   live here are gone — the walkthrough's "Add to home screen" step
-   tells the user how to install for their platform exactly once,
-   then never appears again. Sub-app install lives in the standalone
-   card surfaced from drawer ⋮ on a mini-app. */
+   App.jsx captures beforeinstallprompt early enough to survive account
+   setup; the walkthrough consumes it or shows platform-specific manual
+   guidance. The old drawer banner stays retired. Sub-app installation
+   lives in the standalone card surfaced from drawer ⋮ on a mini-app. */
 
   /* Global offline indicator pill in the top bar. Shown only when the
      browser reports offline (useOnlineStatus). Keeps the user oriented
diff --git a/frontend/src/components/Shell/__tests__/workspaceUi.test.js b/frontend/src/components/Shell/__tests__/workspaceUi.test.js
index 2791d3535..ee0e4b916 100644
--- a/frontend/src/components/Shell/__tests__/workspaceUi.test.js
+++ b/frontend/src/components/Shell/__tests__/workspaceUi.test.js
@@ -122,6 +122,8 @@ test('the first-run walkthrough stays short and action-first', () => {
   assert.match(walkthrough, /Your Möbius is ready/)
   assert.match(walkthrough, /Connect an agent/)
   assert.match(walkthrough, /Open the App Store/)
+  assert.match(walkthrough, /Keep Möbius close/)
+  assert.match(walkthrough, /requestInstall/)
   assert.match(walkthrough, /I’ll explore/)
   assert.match(walkthrough, /mobius:walkthrough-completed/)
 })
diff --git a/frontend/src/components/Walkthrough/WalkthroughOverlay.css b/frontend/src/components/Walkthrough/WalkthroughOverlay.css
index c9afbc033..81e326782 100644
--- a/frontend/src/components/Walkthrough/WalkthroughOverlay.css
+++ b/frontend/src/components/Walkthrough/WalkthroughOverlay.css
@@ -62,6 +62,7 @@
 }
 
 .wt__close:focus-visible,
+.wt__install-btn:focus-visible,
 .wt__path:focus-visible,
 .wt__dismiss:focus-visible {
   outline: 2px solid var(--accent, #8b6cf7);
@@ -116,6 +117,92 @@
   line-height: 1.55;
 }
 
+.wt__install {
+  display: grid;
+  grid-template-columns: 36px minmax(0, 1fr) auto;
+  gap: 4px 10px;
+  align-items: center;
+  margin-top: 18px;
+  padding: 12px;
+  background: color-mix(in srgb, var(--accent, #8b6cf7) 8%, var(--surface2, #1a1f28));
+  border: 1px solid color-mix(in srgb, var(--accent, #8b6cf7) 22%, var(--border, #252b36));
+  border-radius: 12px;
+}
+
+.wt__install-icon {
+  display: grid;
+  place-items: center;
+  width: 36px;
+  height: 36px;
+  color: var(--accent, #a78bfa);
+  background: color-mix(in srgb, var(--accent, #8b6cf7) 15%, transparent);
+  border-radius: 10px;
+}
+
+.wt__install-copy {
+  min-width: 0;
+}
+
+.wt__install-copy h3 {
+  margin: 0;
+  color: var(--text, #e4e4e7);
+  font-size: 14px;
+  font-weight: 680;
+  line-height: 1.25;
+}
+
+.wt__install-copy p {
+  margin: 3px 0 0;
+  color: var(--muted, #a1a1aa);
+  font-size: 12px;
+  line-height: 1.35;
+}
+
+.wt__install-btn {
+  min-height: 34px;
+  padding: 6px 10px;
+  color: var(--accent, #a78bfa);
+  background: color-mix(in srgb, var(--accent, #8b6cf7) 11%, transparent);
+  border: 0;
+  border-radius: 9px;
+  font: inherit;
+  font-size: 12px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.wt__install-btn:hover:not(:disabled) {
+  background: color-mix(in srgb, var(--accent, #8b6cf7) 18%, transparent);
+}
+
+.wt__install-btn:disabled {
+  opacity: 0.64;
+  cursor: wait;
+}
+
+.wt__install-help,
+.wt__install-feedback {
+  grid-column: 2 / -1;
+  margin: 7px 0 0;
+  font-size: 12px;
+  line-height: 1.45;
+}
+
+.wt__install-help {
+  display: grid;
+  gap: 2px;
+  color: var(--muted, #a1a1aa);
+}
+
+.wt__install-help strong {
+  color: var(--text, #e4e4e7);
+  font-weight: 650;
+}
+
+.wt__install-feedback {
+  color: var(--muted, #a1a1aa);
+}
+
 .wt__paths {
   display: grid;
   gap: 1px;
@@ -195,6 +282,11 @@
   .wt__path small {
     white-space: normal;
   }
+
+  .wt__install {
+    grid-template-columns: 34px minmax(0, 1fr) auto;
+    padding: 10px;
+  }
 }
 
 @media (prefers-reduced-motion: reduce) {
diff --git a/frontend/src/components/Walkthrough/WalkthroughOverlay.jsx b/frontend/src/components/Walkthrough/WalkthroughOverlay.jsx
index c88b8a7dd..bcdb4f672 100644
--- a/frontend/src/components/Walkthrough/WalkthroughOverlay.jsx
+++ b/frontend/src/components/Walkthrough/WalkthroughOverlay.jsx
@@ -1,12 +1,32 @@
-import { useEffect, useRef } from 'react'
+import { useEffect, useRef, useState, useSyncExternalStore } from 'react'
 import { useQueryClient } from '@tanstack/react-query'
+import { Download } from 'lucide-react'
 import { api } from '../../api/client.js'
 import { ownerQueries } from '../../hooks/queries.js'
+import {
+  getInstallPromptSnapshot,
+  requestInstall,
+  subscribeInstallPrompt,
+} from '../../lib/installPrompt.js'
+import {
+  detectInstallPlatform,
+  installCopyForPlatform,
+} from '../../utils/installPlatform.js'
 import './WalkthroughOverlay.css'
 
 export default function WalkthroughOverlay({ onDone, onOpenSettings, onExploreApps }) {
   const queryClient = useQueryClient()
   const closingRef = useRef(false)
+  const [platform] = useState(() => detectInstallPlatform())
+  const [installCopy] = useState(() => installCopyForPlatform(platform))
+  const [showInstallHelp, setShowInstallHelp] = useState(false)
+  const [installBusy, setInstallBusy] = useState(false)
+  const [installFeedback, setInstallFeedback] = useState('')
+  const installState = useSyncExternalStore(
+    subscribeInstallPrompt,
+    getInstallPromptSnapshot,
+    getInstallPromptSnapshot,
+  )
 
   function finish() {
     if (closingRef.current) return
@@ -25,16 +45,41 @@ export default function WalkthroughOverlay({ onDone, onOpenSettings, onExploreAp
     action?.()
   }
 
+  async function handleInstall() {
+    setInstallFeedback('')
+    if (installState !== 'ready') {
+      setShowInstallHelp((visible) => !visible)
+      return
+    }
+
+    setInstallBusy(true)
+    const result = await requestInstall()
+    setInstallBusy(false)
+    if (result.outcome === 'accepted') {
+      finish()
+      return
+    }
+
+    setShowInstallHelp(true)
+    setInstallFeedback(
+      result.outcome === 'dismissed'
+        ? 'Not installed. You can use the browser menu whenever you’re ready.'
+        : 'The browser prompt wasn’t available. Use the steps below instead.',
+    )
+  }
+
   useEffect(() => {
-    const standalone =
-      (typeof window !== 'undefined' &&
-        window.matchMedia &&
-        window.matchMedia('(display-mode: standalone)').matches) ||
-      (typeof navigator !== 'undefined' && navigator.standalone === true)
-    if (standalone) finish()
-    // finish is guarded and this should run only once on mount.
+    if (installState === 'installed') finish()
+    // The event can arrive after mount; finish is guarded across rerenders.
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [])
+  }, [installState])
+
+  const nativeInstallReady = installState === 'ready'
+  const installButtonLabel = installBusy
+    ? 'Opening…'
+    : (nativeInstallReady
+        ? 'Install'
+        : (showInstallHelp ? 'Hide' : installCopy.ctaLabel))
 
   return (
     <aside
@@ -59,6 +104,40 @@ export default function WalkthroughOverlay({ onDone, onOpenSettings, onExploreAp
         You can explore now. Add an agent only when you want chats to act and
         build on your behalf.
       </p>
+      <section className="wt__install" aria-labelledby="wt-install-title">
+        <span className="wt__install-icon" aria-hidden="true">
+          <Download size={18} strokeWidth={2} />
+        </span>
+        <div className="wt__install-copy">
+          <h3 id="wt-install-title">Keep Möbius close</h3>
+          <p>
+            {nativeInstallReady
+              ? 'Install it on this device for a full-screen, one-tap launch.'
+              : installCopy.summary}
+          </p>
+        </div>
+        <button
+          type="button"
+          className="wt__install-btn"
+          onClick={handleInstall}
+          disabled={installBusy}
+          aria-expanded={nativeInstallReady ? undefined : showInstallHelp}
+          aria-controls={nativeInstallReady ? undefined : 'wt-install-help'}
+        >
+          {installButtonLabel}
+        </button>
+        {showInstallHelp && (
+          <div className="wt__install-help" id="wt-install-help">
+            <strong>{installCopy.title}</strong>
+            <span>{installCopy.body}</span>
+          </div>
+        )}
+        {installFeedback && (
+          <p className="wt__install-feedback" role="status">
+            {installFeedback}
+          </p>
+        )}
+      </section>
       <div className="wt__paths">
         <button
           type="button"
diff --git a/frontend/src/lib/__tests__/installPrompt.test.js b/frontend/src/lib/__tests__/installPrompt.test.js
new file mode 100644
index 000000000..094e28789
--- /dev/null
+++ b/frontend/src/lib/__tests__/installPrompt.test.js
@@ -0,0 +1,90 @@
+/**
+ * Unit tests for the early PWA install-prompt capture.
+ */
+import { test } from 'node:test'
+import assert from 'node:assert/strict'
+
+async function freshModule() {
+  return import(new URL(`../installPrompt.js?t=${Math.random()}`, import.meta.url))
+}
+
+function makeTarget({ standalone = false } = {}) {
+  const handlers = new Map()
+  return {
+    navigator: { standalone: false },
+    matchMedia: () => ({ matches: standalone }),
+    addEventListener(type, handler) {
+      handlers.set(type, handler)
+    },
+    dispatch(type, event = {}) {
+      handlers.get(type)?.(event)
+    },
+  }
+}
+
+test('captures and consumes a one-shot native install prompt', async () => {
+  const installPrompt = await freshModule()
+  const target = makeTarget()
+  let prevented = false
+  let promptCalls = 0
+  installPrompt.startInstallPromptCapture(target)
+
+  target.dispatch('beforeinstallprompt', {
+    preventDefault() { prevented = true },
+    async prompt() {
+      promptCalls += 1
+      return { outcome: 'accepted' }
+    },
+  })
+
+  assert.equal(prevented, true)
+  assert.equal(installPrompt.getInstallPromptSnapshot(), 'ready')
+  assert.deepEqual(await installPrompt.requestInstall(), { outcome: 'accepted' })
+  assert.equal(promptCalls, 1)
+  assert.equal(installPrompt.getInstallPromptSnapshot(), 'manual')
+  assert.deepEqual(await installPrompt.requestInstall(), { outcome: 'unavailable' })
+  assert.equal(promptCalls, 1)
+})
+
+test('falls back to userChoice for older Chromium prompt results', async () => {
+  const installPrompt = await freshModule()
+  const target = makeTarget()
+  installPrompt.startInstallPromptCapture(target)
+  target.dispatch('beforeinstallprompt', {
+    preventDefault() {},
+    async prompt() {},
+    userChoice: Promise.resolve({ outcome: 'dismissed' }),
+  })
+
+  assert.deepEqual(await installPrompt.requestInstall(), { outcome: 'dismissed' })
+})
+
+test('appinstalled and standalone launch suppress the install invitation', async () => {
+  const captured = await freshModule()
+  const target = makeTarget()
+  captured.startInstallPromptCapture(target)
+  target.dispatch('appinstalled')
+  assert.equal(captured.getInstallPromptSnapshot(), 'installed')
+
+  const standalone = await freshModule()
+  standalone.startInstallPromptCapture(makeTarget({ standalone: true }))
+  assert.equal(standalone.getInstallPromptSnapshot(), 'installed')
+})
+
+test('subscribers are notified when prompt availability changes', async () => {
+  const installPrompt = await freshModule()
+  const target = makeTarget()
+  let changes = 0
+  installPrompt.startInstallPromptCapture(target)
+  const unsubscribe = installPrompt.subscribeInstallPrompt(() => { changes += 1 })
+
+  target.dispatch('beforeinstallprompt', {
+    preventDefault() {},
+    async prompt() { return { outcome: 'dismissed' } },
+  })
+  await installPrompt.requestInstall()
+  unsubscribe()
+  target.dispatch('appinstalled')
+
+  assert.equal(changes, 2)
+})
diff --git a/frontend/src/lib/installPrompt.js b/frontend/src/lib/installPrompt.js
new file mode 100644
index 000000000..f0c040de3
--- /dev/null
+++ b/frontend/src/lib/installPrompt.js
@@ -0,0 +1,80 @@
+/**
+ * Captures the browser's one-shot PWA install prompt for later user action.
+ *
+ * Chromium can emit `beforeinstallprompt` while account setup is still on
+ * screen, before the first-use card has mounted. App.jsx therefore starts
+ * this module eagerly and the card subscribes to its small external-store
+ * interface when it eventually appears.
+ */
+
+let captureStarted = false
+let deferredPrompt = null
+let installed = false
+const listeners = new Set()
+
+function emitChange() {
+  for (const listener of listeners) listener()
+}
+
+function isStandalone(target) {
+  try {
+    if (target?.navigator?.standalone === true) return true
+    return target?.matchMedia?.('(display-mode: standalone)')?.matches === true
+  } catch {
+    return false
+  }
+}
+
+export function startInstallPromptCapture(
+  target = typeof window !== 'undefined' ? window : null,
+) {
+  if (!target || captureStarted) return
+  captureStarted = true
+  installed = isStandalone(target)
+
+  target.addEventListener('beforeinstallprompt', (event) => {
+    if (installed) return
+    event.preventDefault?.()
+    deferredPrompt = event
+    emitChange()
+  })
+
+  target.addEventListener('appinstalled', () => {
+    deferredPrompt = null
+    installed = true
+    emitChange()
+  })
+}
+
+export function getInstallPromptSnapshot() {
+  if (installed) return 'installed'
+  if (deferredPrompt) return 'ready'
+  return 'manual'
+}
+
+export function subscribeInstallPrompt(listener) {
+  listeners.add(listener)
+  return () => listeners.delete(listener)
+}
+
+export async function requestInstall() {
+  const promptEvent = deferredPrompt
+  if (!promptEvent) return { outcome: 'unavailable' }
+
+  // A BeforeInstallPromptEvent can only be used once. Clear it before
+  // awaiting browser UI so a fast second tap cannot call prompt() twice.
+  deferredPrompt = null
+  emitChange()
+
+  try {
+    const promptResult = await promptEvent.prompt()
+    const choice = typeof promptResult?.outcome === 'string'
+      ? promptResult
+      : await promptEvent.userChoice
+    return {
+      outcome: choice?.outcome === 'accepted' ? 'accepted' : 'dismissed',
+    }
+  } catch {
+    return { outcome: 'unavailable' }
+  }
+}
diff --git a/frontend/src/utils/__tests__/installPlatform.test.js b/frontend/src/utils/__tests__/installPlatform.test.js
index 23e3f12a3..a6df7ae14 100644
--- a/frontend/src/utils/__tests__/installPlatform.test.js
+++ b/frontend/src/utils/__tests__/installPlatform.test.js
@@ -1,25 +1,5 @@
 /**
- * Unit tests for installPlatform.js (UA detection + per-platform install
- * copy + clipboard helper).
- *
- * Run with:
- *   cd frontend && node --test src/utils/__tests__/installPlatform.test.js
- *
- * Pure functions only — detectInstallPlatform takes an explicit UA
- * string, installCopyForPlatform takes a plain object, copyOriginUrl
- * touches navigator.clipboard (covered by a stub).
- *
- * Coverage focuses on the branches today's walkthrough relies on:
- *   - iosSafari → arrowDir 'down', includes Share-button copy
- *   - iosNonSafari (CriOS/FxiOS/etc.) → unsupported=true, ctaLabel
- *     'Copy link' (drives WalkthroughOverlay's STEPS_NO_INSTALL filter)
- *   - chromium-on-Android / Chromium-on-desktop → arrowDir 'up'
- *   - firefox-on-desktop → unsupported (Firefox desktop has no PWA
- *     install API)
- *   - empty UA / SSR-style call (no navigator) → no crash
- *
- * If any of these regress, walkthrough renders wrong copy for the
- * platform OR crashes during SSR, both of which are user-visible.
+ * Unit tests for platform detection and manual install instructions.
  */
 import { test } from 'node:test'
 import assert from 'node:assert/strict'
@@ -29,138 +9,133 @@ import {
   installCopyForPlatform,
 } from '../installPlatform.js'
 
-// Real UA strings observed in the wild — keep these literal so a
-// regex tweak in installPlatform.js can be validated against real
-// device output rather than a synthesized minimal string.
 const UA = {
   iosSafari: 'Mozilla/5.0 (iPhone; CPU iPhone OS 17_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.2 Mobile/15E148 Safari/604.1',
   iosChrome: 'Mozilla/5.0 (iPhone; CPU iPhone OS 17_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/120.0.6099.119 Mobile/15E148 Safari/604.1',
   iosFirefox: 'Mozilla/5.0 (iPhone; CPU iPhone OS 17_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/121.0 Mobile/15E148 Safari/605.1.15',
+  ipadDesktop: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.2 Safari/605.1.15',
   androidChrome: 'Mozilla/5.0 (Linux; Android 14; Pixel 8) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.6099.144 Mobile Safari/537.36',
   androidFirefox: 'Mozilla/5.0 (Android 14; Mobile; rv:121.0) Gecko/121.0 Firefox/121.0',
   androidSamsung: 'Mozilla/5.0 (Linux; Android 14; SAMSUNG SM-G991B) AppleWebKit/537.36 (KHTML, like Gecko) SamsungBrowser/23.0 Chrome/115.0.0.0 Mobile Safari/537.36',
   desktopChrome: 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
   desktopEdge: 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0',
-  desktopFirefox: 'Mozilla/5.0 (X11; Linux x86_64; rv:121.0) Gecko/20100101 Firefox/121.0',
+  windowsFirefox: 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:143.0) Gecko/20100101 Firefox/143.0',
+  linuxFirefox: 'Mozilla/5.0 (X11; Linux x86_64; rv:143.0) Gecko/20100101 Firefox/143.0',
+  macSafari: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 14_4) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4 Safari/605.1.15',
 }
 
-test('iOS Safari is detected and NOT treated as iOS-non-Safari', () => {
-  const p = detectInstallPlatform(UA.iosSafari)
-  assert.equal(p.ios, true)
-  assert.equal(p.iosSafari, true)
-  assert.equal(p.iosNonSafari, false)
-  assert.equal(p.bipCapable, false)
-  assert.equal(p.installPossible, true)
-})
+test('iOS Safari and third-party browsers are all install-capable', () => {
+  const safari = detectInstallPlatform(UA.iosSafari)
+  const chrome = detectInstallPlatform(UA.iosChrome)
+  const firefox = detectInstallPlatform(UA.iosFirefox)
 
-test('iOS Chrome (CriOS) is detected as iOS-non-Safari', () => {
-  const p = detectInstallPlatform(UA.iosChrome)
-  assert.equal(p.ios, true)
-  assert.equal(p.iosSafari, false)
-  assert.equal(p.iosNonSafari, true)
-  // Walkthrough relies on this to drop the install step.
-  assert.equal(p.installPossible, false)
+  assert.equal(safari.iosSafari, true)
+  assert.equal(safari.iosNonSafari, false)
+  assert.equal(chrome.iosNonSafari, true)
+  assert.equal(firefox.iosNonSafari, true)
+  assert.equal(safari.installPossible, true)
+  assert.equal(chrome.installPossible, true)
+  assert.equal(firefox.installPossible, true)
 })
 
-test('iOS Firefox (FxiOS) is detected as iOS-non-Safari', () => {
-  const p = detectInstallPlatform(UA.iosFirefox)
-  assert.equal(p.iosSafari, false)
-  assert.equal(p.iosNonSafari, true)
-})
+test('iPadOS desktop UA is not mistaken for desktop Safari', () => {
+  const platform = detectInstallPlatform(UA.ipadDesktop, 5)
+  const copy = installCopyForPlatform(platform)
 
-test('Android Chrome is chromium + android + bipCapable', () => {
-  const p = detectInstallPlatform(UA.androidChrome)
-  assert.equal(p.android, true)
-  assert.equal(p.chromium, true)
-  assert.equal(p.ios, false)
-  assert.equal(p.bipCapable, true)
+  assert.equal(platform.ios, true)
+  assert.equal(platform.desktopSafari, false)
+  assert.match(copy.body, /Add to Home Screen/)
 })
 
-test('Android Firefox is firefox + android (not iosNonSafari)', () => {
-  const p = detectInstallPlatform(UA.androidFirefox)
-  assert.equal(p.firefox, true)
-  assert.equal(p.android, true)
-  assert.equal(p.iosNonSafari, false)
-  assert.equal(p.installPossible, true)
-})
+test('Android install-capable browsers are detected without iOS overlap', () => {
+  const chrome = detectInstallPlatform(UA.androidChrome)
+  const firefox = detectInstallPlatform(UA.androidFirefox)
+  const samsung = detectInstallPlatform(UA.androidSamsung)
 
-test('Samsung Internet is chromium-family on Android', () => {
-  const p = detectInstallPlatform(UA.androidSamsung)
-  assert.equal(p.samsung, true)
-  assert.equal(p.chromium, true)
-  assert.equal(p.android, true)
+  assert.equal(chrome.android, true)
+  assert.equal(chrome.chromium, true)
+  assert.equal(chrome.bipCapable, true)
+  assert.equal(firefox.android, true)
+  assert.equal(firefox.firefox, true)
+  assert.equal(samsung.samsung, true)
+  assert.equal(samsung.chromium, true)
 })
 
-test('Desktop Chrome is chromium + desktop + bipCapable', () => {
-  const p = detectInstallPlatform(UA.desktopChrome)
-  assert.equal(p.chromium, true)
-  assert.equal(p.desktop, true)
-  assert.equal(p.android, false)
-  assert.equal(p.ios, false)
+test('Chromium desktop includes Chrome and Edge', () => {
+  const chrome = detectInstallPlatform(UA.desktopChrome)
+  const edge = detectInstallPlatform(UA.desktopEdge)
+
+  assert.equal(chrome.chromium, true)
+  assert.equal(chrome.desktop, true)
+  assert.equal(edge.edge, true)
+  assert.equal(edge.chromium, true)
 })
 
-test('Desktop Edge is chromium-family (matches Edg/ regex)', () => {
-  const p = detectInstallPlatform(UA.desktopEdge)
-  assert.equal(p.edge, true)
-  assert.equal(p.chromium, true)
+test('Firefox on Windows exposes current web-app instructions', () => {
+  const platform = detectInstallPlatform(UA.windowsFirefox)
+  const copy = installCopyForPlatform(platform)
+
+  assert.equal(platform.firefox, true)
+  assert.equal(platform.windows, true)
+  assert.equal(platform.installPossible, true)
+  assert.equal(copy.unsupported, undefined)
+  assert.match(copy.body, /web-app button/)
 })
 
-test('Desktop Firefox is firefox + desktop and installCopy marks unsupported', () => {
-  const p = detectInstallPlatform(UA.desktopFirefox)
-  assert.equal(p.firefox, true)
-  assert.equal(p.desktop, true)
-  const copy = installCopyForPlatform(p)
+test('Firefox on Linux offers an honest cross-browser fallback', () => {
+  const platform = detectInstallPlatform(UA.linuxFirefox)
+  const copy = installCopyForPlatform(platform)
+
+  assert.equal(platform.windows, false)
+  assert.equal(platform.installPossible, false)
   assert.equal(copy.unsupported, true)
-  assert.equal(copy.arrowDir, null)
+  assert.match(copy.body, /Chrome|Edge|Safari/)
 })
 
-test('Empty UA does not crash (SSR/test safety)', () => {
-  const p = detectInstallPlatform('')
-  assert.equal(typeof p, 'object')
-  assert.equal(p.ios, false)
-  assert.equal(p.android, false)
-})
+test('desktop Safari offers Add to Dock', () => {
+  const platform = detectInstallPlatform(UA.macSafari)
+  const copy = installCopyForPlatform(platform)
 
-test('installCopyForPlatform: iOS Safari shows Share + arrow-down + Got it', () => {
-  const p = detectInstallPlatform(UA.iosSafari)
-  const copy = installCopyForPlatform(p)
-  assert.equal(copy.arrowDir, 'down')
-  assert.equal(copy.ctaLabel, 'Got it')
-  assert.match(copy.body, /Share/)
+  assert.equal(platform.desktopSafari, true)
+  assert.equal(platform.mac, true)
+  assert.match(copy.body, /Add to Dock/)
 })
 
-test('installCopyForPlatform: iOS Chrome shows unsupported + Copy link CTA', () => {
-  const p = detectInstallPlatform(UA.iosChrome)
-  const copy = installCopyForPlatform(p)
-  assert.equal(copy.unsupported, true)
-  assert.equal(copy.ctaLabel, 'Copy link')
+test('empty UA does not crash in non-browser contexts', () => {
+  const platform = detectInstallPlatform('')
+  assert.equal(platform.ios, false)
+  assert.equal(platform.android, false)
+  assert.equal(typeof installCopyForPlatform(platform).summary, 'string')
 })
 
-test('installCopyForPlatform: Android Chrome shows arrow-up + menu instruction', () => {
-  const p = detectInstallPlatform(UA.androidChrome)
-  const copy = installCopyForPlatform(p)
-  assert.equal(copy.arrowDir, 'up')
-  assert.match(copy.body, /menu/)
+test('iOS instructions use the Share menu in Safari, Chrome, and Firefox', () => {
+  for (const ua of [UA.iosSafari, UA.iosChrome, UA.iosFirefox]) {
+    const copy = installCopyForPlatform(detectInstallPlatform(ua))
+    assert.equal(copy.unsupported, undefined)
+    assert.equal(copy.ctaLabel, 'Show me')
+    assert.match(copy.body, /Share/)
+    assert.match(copy.body, /Add to Home Screen/)
+  }
 })
 
-test('installCopyForPlatform: Android Firefox shows arrow-up + menu instruction', () => {
-  const p = detectInstallPlatform(UA.androidFirefox)
-  const copy = installCopyForPlatform(p)
-  assert.equal(copy.arrowDir, 'up')
+test('Android browsers get their own menu wording', () => {
+  const chrome = installCopyForPlatform(detectInstallPlatform(UA.androidChrome))
+  const firefox = installCopyForPlatform(detectInstallPlatform(UA.androidFirefox))
+
+  assert.match(chrome.body, /browser menu/)
+  assert.match(firefox.body, /Firefox menu/)
 })
 
-test('installCopyForPlatform: Desktop Chrome shows arrow-up + address-bar copy', () => {
-  const p = detectInstallPlatform(UA.desktopChrome)
-  const copy = installCopyForPlatform(p)
-  assert.equal(copy.arrowDir, 'up')
-  assert.match(copy.body, /address bar|address-bar/)
+test('desktop Chromium manual fallback names the address bar', () => {
+  const copy = installCopyForPlatform(detectInstallPlatform(UA.desktopChrome))
+  assert.match(copy.body, /address bar/)
 })
 
-test('installCopyForPlatform: fallback for unknown UA returns generic copy', () => {
-  const p = detectInstallPlatform('SomeWeirdEngine/1.0')
-  const copy = installCopyForPlatform(p)
-  // Generic branch: still has a title and body, ctaLabel, no arrow.
-  assert.equal(typeof copy.title, 'string')
-  assert.equal(typeof copy.body, 'string')
-  assert.equal(typeof copy.ctaLabel, 'string')
+test('standalone mode reports installation instead of browser-chrome steps', () => {
+  const copy = installCopyForPlatform(
+    detectInstallPlatform(UA.iosSafari),
+    true,
+  )
+  assert.equal(copy.title, 'Möbius is installed')
+  assert.match(copy.body, /already/)
 })
diff --git a/frontend/src/utils/installPlatform.js b/frontend/src/utils/installPlatform.js
index 79362aac3..7c88c6ef3 100644
--- a/frontend/src/utils/installPlatform.js
+++ b/frontend/src/utils/installPlatform.js
@@ -1,161 +1,138 @@
-// Platform-aware install-instruction helpers.
+// Platform-aware instructions for installing the main Möbius shell.
 //
-// Mirrors the logic baked into `backend/app/routes/standalone.py`'s
-// per-app standalone shell, but for the main Möbius shell. The two
-// can't share source (standalone is Python-rendered HTML, this is an
-// ES module the bundler picks up), but they MUST stay logically in
-// sync — the walkthrough's "Add to home screen" step and the sub-app
-// install card should agree on which arrow points where on a given
-// device.
-//
-// UA-based, fragile-but-fine: we use this for hint copy only. If we
-// guess wrong on an edge case the browser still has its own menu.
-// Feature-detect when possible (matchMedia, navigator.standalone).
+// UA detection is intentionally limited to hint copy. Native install
+// availability is feature-detected separately through `beforeinstallprompt`;
+// if a browser changes its menu, Möbius still leaves installation to the
+// browser rather than pretending a guessed instruction is an API.
 
-export function detectInstallPlatform(ua) {
-  // Default to navigator.userAgent only if we're in a browser. Tests
-  // and any future SSR path can pass an explicit UA without crashing
-  // on undefined `navigator`. The `window.MSStream` check is the same
-  // — only consult it when window exists.
+export function detectInstallPlatform(ua, maxTouchPoints) {
   if (ua === undefined) {
     ua = typeof navigator !== 'undefined' ? (navigator.userAgent || '') : ''
   }
+  if (maxTouchPoints === undefined) {
+    maxTouchPoints = typeof navigator !== 'undefined'
+      ? (navigator.maxTouchPoints || 0)
+      : 0
+  }
   const hasWindow = typeof window !== 'undefined'
-  const ios = /iPad|iPhone|iPod/.test(ua) && !(hasWindow && window.MSStream)
-  // Every iOS browser uses WebKit (Apple gates engine choice until
-  // iOS 17.4 EU). CriOS = Chrome on iOS, FxiOS = Firefox on iOS, etc.
+  // iPadOS can request a desktop UA and identify as Macintosh. Touch points
+  // distinguish that mode from a real Mac for install-copy purposes.
+  const ipadDesktop = /Macintosh/.test(ua) && maxTouchPoints > 1
+  const ios = (/iPad|iPhone|iPod/.test(ua) || ipadDesktop) &&
+    !(hasWindow && window.MSStream)
   const iosNonSafari = ios && /CriOS|FxiOS|EdgiOS|OPiOS|GSA/.test(ua)
   const iosSafari = ios && !iosNonSafari
   const android = /Android/.test(ua)
   const samsung = /SamsungBrowser/.test(ua)
   const edge = /\bEdg\//.test(ua)
   const firefox = /Firefox|FxiOS/.test(ua)
-  // Chromium-family install-capable browsers — Chrome, Edge,
-  // Samsung Internet. CriOS is excluded because Apple forces it to
-  // be WebKit-engined on iOS.
+  const windows = /Windows/.test(ua)
+  const mac = /Macintosh|Mac OS X/.test(ua) && !ios
+  const desktopSafari = !ios && /Safari/.test(ua) &&
+    !/Chrome|Chromium|CriOS|Edg|OPR|Firefox/.test(ua)
   const chromium = !ios && (
     (/Chrome/.test(ua) && !/Edge\//.test(ua)) || edge || samsung
   )
   const desktop = !ios && !android
+
   return {
     ua,
     ios, iosSafari, iosNonSafari,
     android, chromium, edge, firefox, samsung, desktop,
+    desktopSafari, mac, windows,
     // `beforeinstallprompt` can fire here.
     bipCapable: chromium,
-    // PWA install is possible at all on this platform.
-    installPossible: iosSafari || chromium || (firefox && !ios),
+    // iOS 16.4+ allows third-party browsers to expose Add to Home Screen.
+    // Firefox desktop currently supports web apps on Windows only.
+    installPossible: ios || chromium || desktopSafari ||
+      (firefox && (android || windows)),
   }
 }
 
-// Returns rendering hints for the "Add to home screen" walkthrough
-// step. Each shape:
-//   {
-//     title:     short heading
-//     body:      one or two sentences explaining the path
-//     ctaLabel:  the primary-action button label
-//     arrowDir:  'up' | 'down' | null — for any directional UI accent
-//     unsupported: true on platforms where install is impossible
-//                  (renders an alternate CTA, e.g. copy-link)
-//   }
-//
-// The walkthrough overlay doesn't need to know about BIP — by the
-// time the user reaches step 2 they're on a Möbius origin where the
-// real install action is "tap your browser's menu" (Möbius can't
-// reliably auto-fire prompt() at walkthrough-step-2 time, especially
-// for first-time visitors who haven't built engagement yet). The
-// honest copy matches that reality.
-//
-// `standaloneMode` (optional, default false) flags that the caller is
-// ALREADY running inside an installed standalone PWA. On iOS Safari the
-// Share button only exists in the in-browser chrome; a standalone
-// launch has none, so the "tap the Share button below" copy would point
-// at an absent control. When standaloneMode is true on iOS Safari we
-// advise opening the page in Safari proper instead. Default-false keeps
-// the return shape and copy identical for every existing caller — an
-// unset param means "behave exactly as before"; callers that care detect
-// navigator.standalone===true themselves and pass it in.
+// Manual fallback for browsers that do not expose `beforeinstallprompt`.
+// Native prompt availability always wins in the UI; these instructions keep
+// iOS, Android, and desktop useful without it.
 export function installCopyForPlatform(
   p = detectInstallPlatform(),
   standaloneMode = false,
 ) {
-  if (p.iosSafari) {
-    if (standaloneMode) {
-      // Already launched standalone — the Share button isn't on screen.
-      // Tell the user to open the page in Safari, where it lives.
-      return {
-        title: 'Open Möbius in Safari',
-        body: 'You’re already in the installed app, so the Share button isn’t shown here. Open this page in Safari to add another app to your home screen.',
-        ctaLabel: 'Got it',
-        arrowDir: null,
-      }
-    }
+  if (standaloneMode) {
     return {
-      title: 'Add Möbius to your home screen',
-      body: 'Tap the Share button below (the square with the up-arrow), then choose Add to Home Screen.',
+      title: 'Möbius is installed',
+      summary: 'It already opens as an app on this device.',
+      body: 'You’re already using the installed app.',
       ctaLabel: 'Got it',
-      arrowDir: 'down',
     }
   }
-  if (p.iosNonSafari) {
+
+  if (p.ios) {
     return {
-      title: 'Open Möbius in Safari',
-      body: 'On iPhone and iPad, only Safari can install web apps. Copy this page’s link and open it in Safari, then tap Share → Add to Home Screen.',
-      ctaLabel: 'Copy link',
-      arrowDir: null,
-      unsupported: true,
+      title: 'Add Möbius to your Home Screen',
+      summary: 'Use Share, then Add to Home Screen.',
+      body: 'Open your browser’s Share menu, choose Add to Home Screen, keep Open as Web App turned on, then tap Add.',
+      ctaLabel: 'Show me',
     }
   }
+
   if (p.firefox && p.android) {
     return {
-      title: 'Add Möbius to your home screen',
-      body: 'Tap the ⋮ menu at the top right, then choose Install.',
-      ctaLabel: 'Got it',
-      arrowDir: 'up',
+      title: 'Install Möbius',
+      summary: 'Use the Firefox menu to add it.',
+      body: 'Open the Firefox menu, tap Install, then add Möbius to your Home Screen.',
+      ctaLabel: 'Show me',
     }
   }
-  if (p.firefox && p.desktop) {
+
+  if (p.firefox && p.windows) {
     return {
-      title: 'Install isn’t supported in Firefox',
-      body: 'Firefox on desktop doesn’t install web apps. Open Möbius in Chrome or Edge to add it as a desktop app, or just bookmark it.',
-      ctaLabel: 'Got it',
-      arrowDir: null,
-      unsupported: true,
+      title: 'Install Möbius',
+      summary: 'Pin it to your Windows taskbar.',
+      body: 'Click the web-app button in the Firefox address bar. Möbius will open in its own window and appear in your taskbar and Start menu.',
+      ctaLabel: 'Show me',
     }
   }
+
   if (p.chromium && p.android) {
     return {
-      title: 'Add Möbius to your home screen',
-      body: 'Tap the ⋮ menu in the address bar, then Install app (or Add to Home screen).',
-      ctaLabel: 'Got it',
-      arrowDir: 'up',
+      title: 'Install Möbius',
+      summary: 'Use your browser menu to add it.',
+      body: 'Open the browser menu, then choose Install app or Add to Home screen.',
+      ctaLabel: 'Show me',
     }
   }
+
   if (p.chromium && p.desktop) {
     return {
       title: 'Install Möbius',
-      body: 'Click the install icon on the right side of the address bar, or open the ⋮ menu and choose Install Möbius.',
-      ctaLabel: 'Got it',
-      arrowDir: 'up',
+      summary: 'Keep it in your dock or taskbar.',
+      body: 'Click the install icon in the address bar, or open the browser menu and choose Install Möbius.',
+      ctaLabel: 'Show me',
     }
   }
-  return {
-    title: 'Add Möbius to your home screen',
-    body: 'Look for an Install or Add to Home Screen option in your browser’s menu (usually ⋮ or ⋯).',
-    ctaLabel: 'Got it',
-    arrowDir: null,
+
+  if (p.desktopSafari && p.mac) {
+    return {
+      title: 'Add Möbius to your Dock',
+      summary: 'Open it like a Mac app.',
+      body: 'In Safari, open the File menu and choose Add to Dock.',
+      ctaLabel: 'Show me',
+    }
+  }
+
+  if (p.firefox && p.desktop) {
+    return {
+      title: 'Keep Möbius close',
+      summary: 'This Firefox version cannot install web apps.',
+      body: 'Open Möbius in Chrome, Edge, or Safari to install it as an app, or bookmark this page in Firefox.',
+      ctaLabel: 'Options',
+      unsupported: true,
+    }
   }
-}
 
-// Attempts to copy the current URL to the clipboard. Used by the
-// iOS-non-Safari path where the only escape hatch is paste-into-
-// Safari. Returns true on success, false on any clipboard failure
-// (typically lack of permission or the page not being foregrounded).
-export async function copyOriginUrl() {
-  try {
-    await navigator.clipboard.writeText(window.location.href)
-    return true
-  } catch {
-    return false
+  return {
+    title: 'Install Möbius',
+    summary: 'Keep it one click away.',
+    body: 'Look for Install, Add to Home Screen, or Add to Dock in your browser’s address bar or menu.',
+    ctaLabel: 'Show me',
   }
 }