diff --git a/README.md b/README.md
index 27e7b7e..7a7f931 100644
--- a/README.md
+++ b/README.md
@@ -69,7 +69,7 @@ bun run site:build                              # store/site/dist, which the Wor
 
 A merge to `main` that touches the store deploys it, migrations first (`.github/workflows/store.yml`); `main` takes changes through pull requests only.
 
-An app's page there has one way to install it, a button that opens Pocket Hub; that hand-off is not open yet, and the button says so. [docs/applets.md](docs/applets.md) has the store's routes, the website, the publishing rules, the sample data format and what an installed app can reach.
+An app's page there has one way to install it, a button that opens Pocket Hub on the app (a `pocket-hub://store/app/<id>` link); Hub installs it from there. [docs/applets.md](docs/applets.md) has the store's routes, the website, the publishing rules, the sample data format and what an installed app can reach.
 
 ## License
 
diff --git a/docs/applets.md b/docs/applets.md
index 90d96bc..d1ad674 100644
--- a/docs/applets.md
+++ b/docs/applets.md
@@ -48,7 +48,7 @@ bun run typecheck:site
 
 `wrangler dev` and `wrangler deploy` in `store/` run the build themselves (`build` in `store/wrangler.jsonc`), so `store/site/dist` is never committed. What the build copies as it is lives in `store/site/public/`: the response headers (`_headers`), the favicons and the applet player.
 
-**An app's page says what the app is and nothing about which device it fits.** It has the icon, title, summary and publisher, a button that installs it, the app running on its sample data when it has some, and its version, size and date. **Installing is Pocket Hub's**: the button opens Hub, and Hub decides whether a device can run the app and installs it. That hand-off is not open yet, so `hubInstallLink` in `store/site/src/hub.ts` returns no link and the button reads "Not open yet". The page gives no install steps of its own.
+**An app's page says what the app is and nothing about which device it fits.** It has the icon, title, summary and publisher, a button that installs it, the app running on its sample data when it has some, and its version, size and date. **Installing is Pocket Hub's**: the button opens Hub, and Hub decides whether a device can run the app and installs it. The button is a link, `pocket-hub://store/app/<id>`, that the system opens Pocket Hub's Mac app with; `hubInstallLink` in `store/site/src/hub.ts` is the one place that builds it, and Pocket Hub's `docs/DEEP-LINKS.md` is the contract for it. The link carries the app's id and nothing else, and following it only shows the app in Hub: the install is a click there, on a device Hub chose. A browser does not tell a page whether such a link opened anything, so once a visitor has followed it the page says what should have happened and what is missing when nothing did: Pocket Hub, which is not released yet. The page gives no install steps of its own.
 
 **What a package says about itself is one level down**, in a sheet the page's "more" menu opens (`?details=compatibility`, `access`, `versions` or `package`), read from `/v1/manifests` and `/v1/apps/<id>/versions` when it opens: the device of each variant (`rg-ds-plus` is Omarchy Pocket, `tab5-home` the M5Stack Tab5, `3ds-dev` the Nintendo 3DS) with its host ABI, the capabilities the app needs and the ones it uses where a device has them, each with what it lets the app do, and the surface it lays out for; the hosts and services it reaches; every listed version with its package to download; and the id, publisher key, package hash, framework, applet API version and, for each build, its sections' sizes, build hash and profile hash.
 
diff --git a/store/site/src/components/InstallButton.vue b/store/site/src/components/InstallButton.vue
index de2065c..2acfcc3 100644
--- a/store/site/src/components/InstallButton.vue
+++ b/store/site/src/components/InstallButton.vue
@@ -1,7 +1,8 @@
 <script setup lang="ts">
-// The way an app reaches a device: this button opens Pocket Hub, and Hub does
-// the rest. Until that hand-off opens (hub.ts) the button holds its place and
-// says it is not open yet.
+// The way an app reaches a device: this button is a link that opens Pocket
+// Hub on the app (hub.ts), and Hub does the rest. The browser follows it like
+// any link to another program, asking the visitor first, and tells the page
+// nothing of what came of it, so the page is only told that it was followed.
 import { computed } from "vue";
 import { useLanguage } from "../i18n/index.ts";
 import type { StoreApp } from "../api.ts";
@@ -9,19 +10,16 @@ import { hubInstallLink } from "../hub.ts";
 import UiIcon from "./UiIcon.vue";
 
 const props = defineProps<{ app: StoreApp }>();
+defineEmits<{ follow: [] }>();
 const link = computed(() => hubInstallLink(props.app));
 const { t } = useLanguage();
 </script>
 
 <template>
-  <a v-if="link" class="install" :href="link">
+  <a class="install" :href="link" @click="$emit('follow')">
     <UiIcon name="download" :size="22" />
-    <span class="words"><strong>{{ t("install.withHub") }}</strong></span>
+    <strong>{{ t("install.withHub") }}</strong>
   </a>
-  <button v-else class="install" type="button" disabled>
-    <UiIcon name="download" :size="22" />
-    <span class="words"><small>{{ t("install.notOpen") }}</small><strong>{{ t("install.withHub") }}</strong></span>
-  </button>
 </template>
 
 <style scoped>
@@ -34,40 +32,17 @@ const { t } = useLanguage();
   border-radius: 16px;
   background: var(--accent);
   color: var(--on-accent);
-  text-align: left;
   transition: background 0.15s, transform 0.15s var(--ease);
 }
 
-a.install:hover {
+.install:hover {
   background: var(--accent-hover);
 }
 
-a.install:active {
+.install:active {
   transform: scale(0.98);
 }
 
-.install:disabled {
-  background: var(--fill);
-  color: var(--text-2);
-}
-
-.install:disabled .glyph {
-  color: var(--text-3);
-}
-
-.words {
-  display: grid;
-}
-
-small {
-  font-size: 11px;
-  font-weight: 600;
-  line-height: 1.3;
-  letter-spacing: 0.06em;
-  text-transform: uppercase;
-  color: var(--text-3);
-}
-
 strong {
   font-size: 15.5px;
   font-weight: 600;
diff --git a/store/site/src/hub.ts b/store/site/src/hub.ts
index d241062..ff3a749 100644
--- a/store/site/src/hub.ts
+++ b/store/site/src/hub.ts
@@ -1,11 +1,19 @@
 // Installing is Pocket Hub's work, not this page's: the page hands Hub the
-// app, and Hub decides whether a device can run it and installs it. That
-// hand-off is not open yet, so there is no link to give and the install button
-// (components/InstallButton.vue) says so. When it opens, this is the one
-// place that changes.
+// app, and Hub decides whether a device can run it and installs it. The
+// hand-off is a link the system opens Pocket Hub with, and this is the one
+// place that builds it.
+//
+// The link and what Hub does with it are Pocket Hub's docs/DEEP-LINKS.md
+// (§1 the link, §2 what Hub does): pocket-hub://store/app/<id>. It carries
+// the app's id and nothing else, since Hub reads everything about the app out
+// of its own catalog, and following it only shows the app in Hub: installing
+// stays the owner's click there.
 import type { StoreApp } from "./api.ts";
 
-/** The link that opens Pocket Hub on this app, or null while there is none. */
-export function hubInstallLink(_app: StoreApp): string | null {
-  return null;
+/** The link that opens Pocket Hub on this app. */
+export function hubInstallLink(app: StoreApp): string {
+  // An id the store lists needs no encoding (store/src/shared.ts ID). One that
+  // somehow held a "?" or a "#" must not read as another app's id with a
+  // query, which Hub ignores: encoded, Hub refuses the link instead.
+  return `pocket-hub://store/app/${encodeURIComponent(app.id)}`;
 }
diff --git a/store/site/src/i18n/en.ts b/store/site/src/i18n/en.ts
index 14c6ea3..cc27c09 100644
--- a/store/site/src/i18n/en.ts
+++ b/store/site/src/i18n/en.ts
@@ -61,7 +61,7 @@ export default {
   },
   install: {
     withHub: "Install with Pocket Hub",
-    notOpen: "Not open yet",
+    followed: "Pocket Hub should open on this applet now. If nothing happens, this computer has no Pocket Hub: it is a Mac app, and it is not released yet.",
   },
   player: {
     firstScreen: "{title}'s first screen",
diff --git a/store/site/src/i18n/zh-CN.ts b/store/site/src/i18n/zh-CN.ts
index ff0adb7..8f6ed60 100644
--- a/store/site/src/i18n/zh-CN.ts
+++ b/store/site/src/i18n/zh-CN.ts
@@ -59,7 +59,7 @@ const zhCN: Wording = {
   },
   install: {
     withHub: "通过 Pocket Hub 安装",
-    notOpen: "暂未开放",
+    followed: "Pocket Hub 现在应该会打开并显示这个 Applet。如果没有反应，说明这台电脑上还没有 Pocket Hub：它是一款 Mac 应用，目前尚未发布。",
   },
   player: {
     firstScreen: "{title} 的首屏",
diff --git a/store/site/src/pages/AppPage.vue b/store/site/src/pages/AppPage.vue
index 891e121..2aadec3 100644
--- a/store/site/src/pages/AppPage.vue
+++ b/store/site/src/pages/AppPage.vue
@@ -3,6 +3,11 @@
 // Nothing here says which devices it fits or what it asks of them: Pocket Hub
 // settles that at install, and the curious find it one level down, in the
 // details sheet the "more" menu opens (?details=<section>).
+//
+// The button opens Pocket Hub on the app (hub.ts). A browser does not say
+// whether a link to another program opened one, so once the visitor has
+// followed it the page says what should have happened, and what is missing
+// when nothing did.
 import { computed, onBeforeUnmount, ref } from "vue";
 import { useLanguage } from "../i18n/index.ts";
 import { RouterLink, useRoute, useRouter } from "vue-router";
@@ -63,6 +68,9 @@ function shut() {
   else void router.replace({ query: {} });
 }
 
+/** The visitor followed the button's link into Pocket Hub. */
+const followed = ref(false);
+
 const copied = ref(false);
 let fading: ReturnType<typeof setTimeout> | undefined;
 async function copyLink() {
@@ -116,10 +124,11 @@ onBeforeUnmount(() => clearTimeout(fading));
               <span v-if="app.official" class="visually-hidden">{{ t("app.official") }}</span>
             </RouterLink>
             <div class="actions">
-              <InstallButton :app="app" />
+              <InstallButton :app="app" @follow="followed = true" />
               <MenuButton :label="t('app.more')" :items="menu" @choose="choose" />
             </div>
           </div>
+          <p v-if="followed" class="followed" role="status">{{ t("install.followed") }}</p>
           <AppPlayer v-if="app.mock" :app="app" />
         </section>
 
@@ -275,6 +284,26 @@ h1 {
   margin-top: 30px;
 }
 
+/* What the page says once the button was followed goes in the row under the
+   screen, like what the player opens there: the name above it does not move. */
+.followed {
+  grid-area: 2 / 1;
+  align-self: start;
+  max-width: 31em;
+  font-size: 13.5px;
+  line-height: 1.45;
+  color: var(--text-2);
+  text-wrap: pretty;
+  animation: followed-in 0.3s var(--ease) both;
+}
+
+@keyframes followed-in {
+  from {
+    opacity: 0;
+    transform: translateY(-4px);
+  }
+}
+
 .facts {
   display: grid;
   grid-template-columns: repeat(4, minmax(0, 1fr));
@@ -433,6 +462,13 @@ h1 {
     justify-content: center;
   }
 
+  /* one column: under the buttons, nearer to them than to the screen */
+  .followed {
+    grid-area: auto;
+    max-width: none;
+    margin: -14px 0 16px;
+  }
+
   .ghost-title,
   .ghost-line {
     margin-top: 0;
diff --git a/store/test/hub.test.ts b/store/test/hub.test.ts
new file mode 100644
index 0000000..bfa30ed
--- /dev/null
+++ b/store/test/hub.test.ts
@@ -0,0 +1,30 @@
+// The link the website's install button carries into Pocket Hub. Its grammar
+// is Pocket Hub's docs/DEEP-LINKS.md §1, and Hub refuses anything outside it,
+// so this holds the website to exactly that shape.
+import { expect, test } from "bun:test";
+import type { StoreApp } from "../site/src/api.ts";
+import { hubInstallLink } from "../site/src/hub.ts";
+import { ID } from "../src/shared.ts";
+
+const app = (id: string) => ({ id }) as StoreApp;
+
+/** What Hub takes for a link: the scheme, the host `store`, `/app/` and an id of the store's shape. */
+const LINK = new RegExp(`^pocket-hub://store/app/(${ID.source.slice(1, -1)})$`);
+
+test("an app's link into Pocket Hub is its id under pocket-hub://store/app", () => {
+  expect(hubInstallLink(app("dev.pocket-nexus.hn"))).toBe("pocket-hub://store/app/dev.pocket-nexus.hn");
+  for (const id of ["dev.pocket-nexus.hn", "io.example.pixels", "a1.b2.c3.d4.e5.f6"]) {
+    expect(ID.test(id)).toBe(true);
+    expect(hubInstallLink(app(id)).match(LINK)?.[1]).toBe(id);
+  }
+});
+
+test("an id outside the store's shape never reads as another app's link", () => {
+  // Hub ignores a query and a fragment: unencoded, these would open dev.pocket-nexus.hn.
+  for (const id of ["dev.pocket-nexus.hn?x=1", "dev.pocket-nexus.hn#top", "dev.pocket-nexus.hn/../x"]) {
+    const link = hubInstallLink(app(id));
+    expect(LINK.test(link)).toBe(false);
+    expect(new URL(link).search + new URL(link).hash).toBe("");
+    expect(new URL(link).pathname.split("/").length).toBe(3);
+  }
+});