diff --git a/client/src/components/Sidebar.tsx b/client/src/components/Sidebar.tsx
index 75882d06..b3ac6024 100644
--- a/client/src/components/Sidebar.tsx
+++ b/client/src/components/Sidebar.tsx
@@ -368,15 +368,25 @@ export function Sidebar({ wsConnected, collapsed, onToggle }: SidebarProps) {
     ? t("nav:checkingForUpdates")
     : checkError
       ? t("nav:checkFailed")
-      : updateAvailable
-        ? updateStatus?.latest_release
-          ? t("nav:releaseAvailable", { version: updateStatus.latest_release })
-          : t("nav:updateAvailable")
-        : updateStatus?.dev_build
-          ? t("nav:devBuild", { count: updateStatus.commits_ahead_of_release ?? 0 })
-          : updateStatus
-            ? t("nav:upToDate")
-            : t("nav:checkForUpdates");
+      : updateStatus?.installed_not_running
+        ? t("nav:installedNotRunning", {
+            version: updateStatus.installed_not_running.version ?? "?",
+          })
+        : updateAvailable
+          ? updateStatus?.latest_release
+            ? t("nav:releaseAvailable", { version: updateStatus.latest_release })
+            : t("nav:updateAvailable")
+          : updateStatus?.dev_build
+            ? t("nav:devBuild", { count: updateStatus.commits_ahead_of_release ?? 0 })
+            : // A plugin install has no commit count to fall back on: a release
+              // that could not be read is "unknown", never "up to date".
+              updateStatus?.install_kind === "plugin" &&
+                updateStatus.release_check &&
+                updateStatus.release_check !== "ok"
+              ? t("nav:releaseUnchecked")
+              : updateStatus
+                ? t("nav:upToDate")
+                : t("nav:checkForUpdates");
   const currentLanguage = normalizeLanguage(i18n.resolvedLanguage ?? i18n.language);
   const currentIndex = SUPPORTED_LANGUAGES.indexOf(currentLanguage);
   const nextLanguage = SUPPORTED_LANGUAGES[(currentIndex + 1) % SUPPORTED_LANGUAGES.length];
diff --git a/client/src/components/UpdateNotifier.tsx b/client/src/components/UpdateNotifier.tsx
index f85327aa..33974003 100644
--- a/client/src/components/UpdateNotifier.tsx
+++ b/client/src/components/UpdateNotifier.tsx
@@ -185,7 +185,13 @@ export function UpdateNotifier() {
   // also swallow v1.6.0 — and so the prompt survives the tag pointing at a
   // commit the user already has. Falls back to the upstream SHA for the
   // commit-count path (no release readable).
-  const dismissKey = status?.latest_release || status?.remote_sha || null;
+  // A build installed from a terminal while this server kept running has no
+  // tag or sha when the forge is unreachable — key it by its directory.
+  const installed = status?.installed_not_running ?? null;
+  const dismissKey =
+    status?.latest_release ||
+    status?.remote_sha ||
+    (installed ? `installed:${installed.root}` : null);
   const show = Boolean(status?.update_available && dismissKey && dismissedSha !== dismissKey);
 
   const dismiss = useCallback(() => {
@@ -320,12 +326,16 @@ export function UpdateNotifier() {
                 id="update-notifier-title"
                 className="text-sm font-semibold text-fg-primary truncate"
               >
-                {release ? t("releaseTitle", { version: release }) : t("title")}
+                {installed
+                  ? t("installedTitle", { version: installed.version ?? "?" })
+                  : release
+                    ? t("releaseTitle", { version: release })
+                    : t("title")}
               </h2>
               <p className="text-[11px] text-fg-muted mt-0.5 font-mono truncate">
                 {/* Never print a commit count on a shallow clone — the number
                     is a graft artefact, not a distance. */}
-                {release && !status.shallow_clone && status.local_version
+                {(release || installed) && !status.shallow_clone && status.local_version
                   ? t("releaseSubtitle", { current: status.local_version })
                   : t("commitsBehind", { count: behind, ref: refLabel })}
               </p>
diff --git a/client/src/components/__tests__/Sidebar.test.tsx b/client/src/components/__tests__/Sidebar.test.tsx
index 2f4fd51f..a77cf7de 100644
--- a/client/src/components/__tests__/Sidebar.test.tsx
+++ b/client/src/components/__tests__/Sidebar.test.tsx
@@ -5,10 +5,11 @@
  */
 
 import { describe, it, expect } from "vitest";
-import { render, screen, waitFor } from "@testing-library/react";
+import { act, render, screen, waitFor } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
 import { MemoryRouter } from "react-router-dom";
 import { Sidebar } from "../Sidebar";
+import { eventBus } from "../../lib/eventBus";
 
 function renderSidebar(wsConnected: boolean, collapsed = false) {
   return render(
@@ -103,4 +104,44 @@ describe("Sidebar", () => {
       expect(screen.getByText("VI")).toBeInTheDocument();
     });
   });
+
+  describe("update status line", () => {
+    const plugin = {
+      git_repo: false,
+      install_kind: "plugin",
+      situation: "plugin_managed",
+      local_version: "1.8.10",
+    };
+    const publish = (data: object) =>
+      act(() => eventBus.publish({ type: "update_status", data } as never));
+
+    it("does not claim up to date when a plugin install could not read the release", () => {
+      renderSidebar(true);
+      publish({ ...plugin, update_available: false, release_check: "unreachable" });
+      expect(screen.queryByText("Up to date")).toBeNull();
+      expect(screen.getByText("Could not check for updates")).toBeInTheDocument();
+    });
+
+    it("names a build installed beside the running one", () => {
+      renderSidebar(true);
+      publish({
+        ...plugin,
+        update_available: true,
+        release_check: "unreachable",
+        installed_not_running: { root: "/x", version: "1.8.12" },
+      });
+      expect(screen.getByText("1.8.12 installed, not running")).toBeInTheDocument();
+    });
+
+    it("still says up to date when the release was read and matches", () => {
+      renderSidebar(true);
+      publish({
+        ...plugin,
+        update_available: false,
+        release_check: "ok",
+        latest_release: "v1.8.10",
+      });
+      expect(screen.getByText("Up to date")).toBeInTheDocument();
+    });
+  });
 });
diff --git a/client/src/components/__tests__/UpdateNotifier.test.tsx b/client/src/components/__tests__/UpdateNotifier.test.tsx
index b3793719..3dac8876 100644
--- a/client/src/components/__tests__/UpdateNotifier.test.tsx
+++ b/client/src/components/__tests__/UpdateNotifier.test.tsx
@@ -137,6 +137,33 @@ describe("UpdateNotifier — Update now", () => {
     expect(screen.queryByText(i18n.t("updates:notGit"))).not.toBeInTheDocument();
   });
 
+  it("offers Update now for a build installed from a terminal, even with no release read", async () => {
+    // `claude plugin update` started nothing and the forge was unreachable:
+    // no release tag and no sha to key the modal on, yet a newer build sits
+    // on disk. That used to read as "up to date" with no way to switch.
+    statusMock.mockResolvedValue({
+      ...BASE_STATUS,
+      git_repo: false,
+      situation: "plugin_managed",
+      install_kind: "plugin",
+      plugin_marketplace: "sg",
+      plugin_name: "agenthub",
+      remote_sha: null,
+      commits_behind: 0,
+      local_version: "1.8.10",
+      release_check: "unreachable",
+      latest_release: null,
+      installed_not_running: { root: "/cache/sg/agenthub/new", version: "1.8.12" },
+    });
+    render(<UpdateNotifier />);
+
+    await screen.findByText(i18n.t("updates:installedTitle", { version: "1.8.12" }));
+    expect(
+      screen.getByText(i18n.t("updates:releaseSubtitle", { current: "1.8.10" }))
+    ).toBeInTheDocument();
+    expect(screen.getByText(i18n.t("updates:updateNow"))).toBeInTheDocument();
+  });
+
   it("surfaces a previous plugin chain's failure so a dead update isn't silent", async () => {
     statusMock.mockResolvedValue({
       ...BASE_STATUS,
diff --git a/client/src/i18n/locales/en/nav.json b/client/src/i18n/locales/en/nav.json
index 9b533636..7f9d462b 100644
--- a/client/src/i18n/locales/en/nav.json
+++ b/client/src/i18n/locales/en/nav.json
@@ -68,5 +68,7 @@
   "workspace": "Workspace",
   "wsEndpoint": "WebSocket",
   "releaseAvailable": "{{version}} available",
-  "devBuild": "Dev build · {{count}} ahead"
+  "devBuild": "Dev build · {{count}} ahead",
+  "installedNotRunning": "{{version}} installed, not running",
+  "releaseUnchecked": "Could not check for updates"
 }
diff --git a/client/src/i18n/locales/en/updates.json b/client/src/i18n/locales/en/updates.json
index 031abdd3..e87ba6cf 100644
--- a/client/src/i18n/locales/en/updates.json
+++ b/client/src/i18n/locales/en/updates.json
@@ -26,5 +26,6 @@
   "pluginAutoNote": "This dashboard is installed as a Claude Code plugin. \"Update now\" pulls the new plugin version, reinstalls the runtime, and restarts the server for you — it takes a few minutes. Newly added skills and slash commands only appear in an already-open Claude Code session after you run /reload-plugins there.",
   "pluginUpdating": "Pulling the new plugin version and reinstalling the runtime — this takes a few minutes, the page reloads itself when the new server is up...",
   "lastPluginUpdateFailed": "The last plugin update failed at step \"{{step}}\": {{error}} — run /agenthub-update in Claude Code to recover.",
-  "restartingShort": "Restarting…"
+  "restartingShort": "Restarting…",
+  "installedTitle": "Version {{version}} is installed but not running"
 }
diff --git a/client/src/i18n/locales/vi/nav.json b/client/src/i18n/locales/vi/nav.json
index dbf3046b..ed487baf 100644
--- a/client/src/i18n/locales/vi/nav.json
+++ b/client/src/i18n/locales/vi/nav.json
@@ -68,5 +68,7 @@
   "workspace": "Không gian làm việc",
   "wsEndpoint": "WebSocket",
   "releaseAvailable": "Có {{version}}",
-  "devBuild": "Bản dev · trước {{count}} commit"
+  "devBuild": "Bản dev · trước {{count}} commit",
+  "installedNotRunning": "Đã cài {{version}}, chưa chạy",
+  "releaseUnchecked": "Không kiểm tra được bản mới"
 }
diff --git a/client/src/i18n/locales/vi/updates.json b/client/src/i18n/locales/vi/updates.json
index 0fa9194f..ea130491 100644
--- a/client/src/i18n/locales/vi/updates.json
+++ b/client/src/i18n/locales/vi/updates.json
@@ -26,5 +26,6 @@
   "pluginAutoNote": "Dashboard này cài dạng plugin của Claude Code. Bấm \"Cập nhật ngay\" sẽ tự tải bản plugin mới, cài lại runtime và khởi động lại server — mất vài phút. Riêng skill và slash command mới thì session Claude Code đang mở chỉ thấy sau khi bạn chạy /reload-plugins ở đó.",
   "pluginUpdating": "Đang tải bản plugin mới và cài lại runtime — mất vài phút, trang sẽ tự reload khi server mới lên...",
   "lastPluginUpdateFailed": "Lần cập nhật plugin trước thất bại ở bước \"{{step}}\": {{error}} — chạy /agenthub-update trong Claude Code để khắc phục.",
-  "restartingShort": "Đang khởi động lại…"
+  "restartingShort": "Đang khởi động lại…",
+  "installedTitle": "Đã cài bản {{version}} nhưng chưa chạy"
 }
diff --git a/client/src/lib/types.ts b/client/src/lib/types.ts
index cfb45c1e..3c187978 100644
--- a/client/src/lib/types.ts
+++ b/client/src/lib/types.ts
@@ -1352,6 +1352,10 @@ export interface UpdateStatusPayload {
    *  or `"http_<status>"`. Anything but `"ok"` means detection fell back to
    *  the commit-count comparison. */
   release_check?: string;
+  /** Plugin installs only: a newer build Claude Code has installed beside the
+   *  running one (`claude plugin update` from a terminal starts nothing), or
+   *  null. Sets `update_available`; "Update now" hands the server over to it. */
+  installed_not_running?: { root: string; version: string | null } | null;
   /** Tag of the newest published release, e.g. `"v1.5.0"`. null when
    *  `release_check !== "ok"`. */
   latest_release?: string | null;
diff --git a/docs/PLUGINS.md b/docs/PLUGINS.md
index 7ca1a989..8e18be8a 100644
--- a/docs/PLUGINS.md
+++ b/docs/PLUGINS.md
@@ -185,6 +185,34 @@ key, which holds without parsing a cache path or trusting a name. An entry
 pointing at a directory that no longer exists is ignored — a phantom must never
 wedge a bootstrap shut.
 
+### A build installed while the server kept running
+
+The same record answers the opposite case. `claude plugin update` run from a
+terminal (or with only the Claude desktop app open) starts **nothing**: no
+SessionStart fires, so no bootstrap hands the server over, and the dashboard
+keeps running the old directory — across reboots too, since
+`agenthub.service` still names it and it still exists. `agenthub open` only
+opens the browser.
+
+So `getUpdatesStatus` (`server/lib/update-check.js`) asks `supersededBy` for
+its own root: when a sibling build is the installed one, the status carries
+`installed_not_running: {root, version}` and `update_available: true` — with
+no network needed, so an unreachable forge can no longer hide it. The sidebar
+reads **`<version>` installed, not running**, and the update modal's **Update
+now** runs the usual chain; `scripts/plugin-update-helper.js` hands over to the
+recorded install first (`supersededBy(oldRoot)`), falling back to the newest
+sibling directory only when there is no record.
+
+Separately, a plugin install whose release lookup failed (`release_check` not
+`ok`) now reads **Could not check for updates** in the sidebar instead of
+**Up to date** — a plugin install has no commit count to fall back on.
+
+To hand over by hand without the dashboard:
+
+```bash
+node "$(python3 -c 'import json,os;d=json.load(open(os.path.expanduser("~/.claude/plugins/installed_plugins.json")));print([e["installPath"] for k,v in d["plugins"].items() if k.startswith("agenthub@") for e in v][0])')/scripts/plugin-bootstrap.js" --force
+```
+
 ### Pruning the plugin cache
 
 Claude Code unpacks every update beside the last one and does not reliably
diff --git a/scripts/plugin-update-helper.js b/scripts/plugin-update-helper.js
index 2caa2b89..87015881 100644
--- a/scripts/plugin-update-helper.js
+++ b/scripts/plugin-update-helper.js
@@ -158,7 +158,10 @@ function main() {
     return;
   }
 
-  const newRoot = findNewRoot(oldRoot);
+  // Claude Code's own install record first: newest-mtime is only a guess, and a
+  // build installed from a terminal while this server kept running is exactly
+  // the one to hand over to, whether or not this chain pulled anything.
+  const newRoot = require("./plugin-bootstrap").supersededBy(oldRoot) || findNewRoot(oldRoot);
   if (!newRoot) {
     // Already newest: the marketplace had nothing to pull. Not a failure — the
     // old server is still running and untouched, so say so plainly.
diff --git a/server/__tests__/update-check-plugin-nogit.test.js b/server/__tests__/update-check-plugin-nogit.test.js
index fbb402fe..bdbd0add 100644
--- a/server/__tests__/update-check-plugin-nogit.test.js
+++ b/server/__tests__/update-check-plugin-nogit.test.js
@@ -384,3 +384,39 @@ describe("fetchReleaseFromUrl", () => {
     }
   });
 });
+
+describe("a newer build installed beside the running one", () => {
+  /** Record `installed` as Claude Code's install of agenthub@sg. */
+  function recordInstall(home, installed) {
+    fs.writeFileSync(
+      path.join(home, "plugins", "installed_plugins.json"),
+      JSON.stringify({ plugins: { "agenthub@sg": [{ scope: "user", installPath: installed }] } })
+    );
+  }
+
+  it("reports an update even when the release check fails", async () => {
+    // `claude plugin update` from a terminal unpacks the new build and starts
+    // nothing: the server keeps running the old directory, and with the forge
+    // unreachable it used to answer "up to date" forever.
+    const { root, home } = makePluginInstall("installed-newer", { version: "1.8.10" });
+    const newer = path.join(path.dirname(root), "aaaaaaaaaaaa");
+    fs.mkdirSync(newer, { recursive: true });
+    fs.writeFileSync(path.join(newer, "package.json"), JSON.stringify({ version: "1.8.12" }));
+    recordInstall(home, newer);
+
+    const s = await getUpdatesStatus(root, {
+      latestRelease: { ok: false, reason: "unreachable" },
+    });
+    assert.equal(s.update_available, true);
+    assert.deepEqual(s.installed_not_running, { root: newer, version: "1.8.12" });
+    assert.match(s.message, /1\.8\.12 is installed but not running/);
+  });
+
+  it("says nothing extra when the running build is the installed one", async () => {
+    const { root, home } = makePluginInstall("installed-same", { version: "1.8.12" });
+    recordInstall(home, root);
+    const s = await getUpdatesStatus(root, { latestRelease: release("v1.8.12") });
+    assert.equal(s.update_available, false);
+    assert.equal(s.installed_not_running, null);
+  });
+});
diff --git a/server/lib/update-check.js b/server/lib/update-check.js
index c9509683..f0b69094 100644
--- a/server/lib/update-check.js
+++ b/server/lib/update-check.js
@@ -415,6 +415,18 @@ async function pluginStatus(root, pluginInstall, options = {}) {
   const comparable = release.ok && Boolean(localVersion);
   const releaseIsNewer = comparable && compareVersions(release.tag, localVersion) > 0;
 
+  // `claude plugin update` run from a terminal unpacks the new build into a
+  // sibling cache dir and starts NOTHING — only a SessionStart or this
+  // dashboard's own update chain hands the server over. Without a Claude Code
+  // session this server ran the old build forever, and with the forge
+  // unreachable it said "up to date". The local record needs no network, and
+  // "Update now" already re-bootstraps from the newest sibling.
+  const installedRoot = require("../../scripts/plugin-bootstrap").supersededBy(root);
+  const installedNotRunning = installedRoot
+    ? { root: installedRoot, version: readLocalVersion(installedRoot) }
+    : null;
+  const updateAvailable = releaseIsNewer || Boolean(installedNotRunning);
+
   const manualParts = [
     `claude plugin marketplace update ${pluginInstall.marketplace}`,
     `claude plugin update ${pluginInstall.plugin}@${pluginInstall.marketplace} -y`,
@@ -425,7 +437,8 @@ async function pluginStatus(root, pluginInstall, options = {}) {
     // `install_kind`, not on this, or they will report "check manually" for an
     // install the dashboard can in fact check AND update.
     git_repo: false,
-    update_available: releaseIsNewer,
+    update_available: updateAvailable,
+    installed_not_running: installedNotRunning,
     repo_root: root,
     situation: "plugin_managed",
     situation_note:
@@ -438,13 +451,16 @@ async function pluginStatus(root, pluginInstall, options = {}) {
     // gets the same sentence. Left null, `agenthub update-check` printed the
     // literal "null" as its headline on every plugin-cache install — the one
     // install kind that cannot fall back to a commit count.
-    message: releaseIsNewer
-      ? `Release ${release.tag} is available (this install reports ${localVersion || "no version"}).`
-      : comparable
-        ? `Running the newest release (${release.tag}).`
-        : release.ok
-          ? `This install reports no version, so it cannot be compared with release ${release.tag}.`
-          : `Could not read the latest release (${release.reason}); version comparison unavailable.`,
+    message: installedNotRunning
+      ? `Version ${installedNotRunning.version || "(unknown)"} is installed but not running ` +
+        `(this server runs ${localVersion || "no version"}); "Update now" switches the dashboard to it.`
+      : releaseIsNewer
+        ? `Release ${release.tag} is available (this install reports ${localVersion || "no version"}).`
+        : comparable
+          ? `Running the newest release (${release.tag}).`
+          : release.ok
+            ? `This install reports no version, so it cannot be compared with release ${release.tag}.`
+            : `Could not read the latest release (${release.reason}); version comparison unavailable.`,
 
     install_kind: "plugin",
     plugin_marketplace: pluginInstall.marketplace,
diff --git a/server/openapi.js b/server/openapi.js
index b246d3d3..8cf43419 100644
--- a/server/openapi.js
+++ b/server/openapi.js
@@ -2419,7 +2419,7 @@ function createOpenApiSpec() {
                     type: "object",
                     additionalProperties: true,
                     description:
-                      'Reads the newest published release from the forge API (derived from the origin remote) and compares its tag against this install\'s package.json version; falls back to a commit count against the canonical default branch when no release can be read, with the reason in release_check. Includes git_repo, update_available, install_kind ("plugin" | "checkout"), plugin_marketplace, local_version, shallow_clone, release_check, latest_release, latest_release_name, latest_release_url, latest_release_published_at, latest_release_notes, release_sha, commits_behind_release, commits_ahead_of_release, dev_build, commits_behind, remote_ref, local_sha, remote_sha, situation, manual_command, and optional error/message fields. dev_build is true when this install is strictly ahead of the newest release; commits_* fields are null on a shallow clone, where distances are meaningless.',
+                      'Reads the newest published release from the forge API (derived from the origin remote) and compares its tag against this install\'s package.json version; falls back to a commit count against the canonical default branch when no release can be read, with the reason in release_check. Includes git_repo, update_available, install_kind ("plugin" | "checkout"), plugin_marketplace, local_version, shallow_clone, release_check, latest_release, latest_release_name, latest_release_url, latest_release_published_at, latest_release_notes, release_sha, commits_behind_release, commits_ahead_of_release, dev_build, commits_behind, remote_ref, local_sha, remote_sha, situation, manual_command, and optional error/message fields. installed_not_running ({root, version} or null, plugin installs only) names a newer build Claude Code installed beside the running one and sets update_available without any network; dev_build is true when this install is strictly ahead of the newest release; commits_* fields are null on a shallow clone, where distances are meaningless.',
                   },
                 },
               },