diff --git a/frontend/package.json b/frontend/package.json
index 2279b12..0c9176b 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -6,8 +6,10 @@
   "author": "Vesti",
   "scripts": {
     "dev": "plasmo dev",
+    "dev:firefox": "plasmo dev --target=firefox-mv3",
     "prebuild": "pnpm -C ../packages/vesti-ui build && pnpm -C .. install --frozen-lockfile",
     "build": "plasmo build",
+    "build:firefox": "plasmo build --target=firefox-mv3",
     "package": "node -e \"console.error('Local packaging is disabled. Use CI workflow extension-package or run pnpm -C frontend package:safe.'); process.exit(1)\"",
     "package:ci": "pnpm run build && plasmo package",
     "package:safe": "powershell -NoProfile -ExecutionPolicy Bypass -File ../scripts/safe-package.ps1 -Overwrite",
diff --git a/frontend/src/background/index.ts b/frontend/src/background/index.ts
index 92e9309..806b4c5 100644
--- a/frontend/src/background/index.ts
+++ b/frontend/src/background/index.ts
@@ -638,13 +638,64 @@ if (chrome?.alarms?.create) {
 }
 
 function openSidepanelForTab(tabId: number): void {
-  if (!chrome?.sidePanel?.open) {
-    logger.warn("background", "sidePanel API not available");
+  const openLibraryTab = () => {
+    const url = chrome.runtime.getURL("options.html?tab=library");
+    chrome.tabs.create({ url }, () => {
+      void chrome.runtime.lastError;
+    });
+  };
+
+  if (chrome?.sidePanel?.open) {
+    chrome.sidePanel.setOptions({ tabId, path: "sidepanel.html", enabled: true }, () => {
+      chrome.sidePanel.open({ tabId }, () => {
+        void chrome.runtime.lastError;
+      });
+    });
     return;
   }
-  chrome.sidePanel.setOptions({ tabId, path: "sidepanel.html", enabled: true }, () => {
-    chrome.sidePanel.open({ tabId }, () => {
-      void chrome.runtime.lastError;
+
+  const browserSidebarAction = (
+    globalThis as typeof globalThis & {
+      browser?: {
+        sidebarAction?: {
+          open?: () => Promise<void>;
+        };
+      };
+    }
+  ).browser?.sidebarAction;
+
+  if (typeof browserSidebarAction?.open === "function") {
+    void browserSidebarAction.open().catch((error) => {
+      logger.warn("background", "sidebarAction.open failed; falling back to options tab", {
+        error: (error as Error)?.message ?? String(error),
+      });
+      openLibraryTab();
+    });
+    return;
+  }
+
+  logger.warn("background", "No side panel API available; falling back to options tab");
+  openLibraryTab();
+}
+
+if (chrome?.action?.onClicked) {
+  chrome.action.onClicked.addListener((tab) => {
+    const tabId = tab.id;
+    if (typeof tabId === "number") {
+      openSidepanelForTab(tabId);
+      return;
+    }
+
+    chrome.tabs.query({ active: true, currentWindow: true }, (tabs) => {
+      const activeId = tabs[0]?.id;
+      if (typeof activeId === "number") {
+        openSidepanelForTab(activeId);
+      } else {
+        const url = chrome.runtime.getURL("options.html?tab=library");
+        chrome.tabs.create({ url }, () => {
+          void chrome.runtime.lastError;
+        });
+      }
     });
   });
 }