perf(extension): gate iframe content script injection

.changeset/quiet-frames-speedometer.md

@@ -0,0 +1,5 @@
+---
+"@read-frog/extension": patch
+---
+
+perf(extension): gate iframe content script injection

src/entrypoints/background/__tests__/iframe-injection.test.ts

@@ -1,3 +1,4 @@
+import { browser, storage } from "#imports"
 import { beforeEach, describe, expect, it, vi } from "vitest"
 import { SITE_CONTROL_URL_WINDOW_KEY } from "@/utils/site-control"
 
@@ -6,39 +7,12 @@ const webNavigationOnBeforeNavigateAddListenerMock = vi.fn()
 const webNavigationOnCompletedAddListenerMock = vi.fn()
 const getAllFramesMock = vi.fn()
 const executeScriptMock = vi.fn()
+const storageGetItemMock = vi.fn()
 
 const getLocalConfigMock = vi.fn()
 const loggerErrorMock = vi.fn()
 const loggerWarnMock = vi.fn()
 
-const browserMock = {
-  tabs: {
-    onRemoved: {
-      addListener: tabsOnRemovedAddListenerMock,
-    },
-  },
-  webNavigation: {
-    onBeforeNavigate: {
-      addListener: webNavigationOnBeforeNavigateAddListenerMock,
-    },
-    onCompleted: {
-      addListener: webNavigationOnCompletedAddListenerMock,
-    },
-    getAllFrames: getAllFramesMock,
-  },
-  scripting: {
-    executeScript: executeScriptMock,
-  },
-}
-
-vi.mock("#imports", () => ({
-  browser: browserMock,
-}))
-
-vi.mock("wxt/browser", () => ({
-  browser: browserMock,
-}))
-
 vi.mock("@/utils/config/storage", () => ({
   getLocalConfig: getLocalConfigMock,
 }))
@@ -109,14 +83,32 @@ describe("setupIframeInjection", () => {
     vi.clearAllMocks()
     currentTabId += 1
 
+    browser.tabs.onRemoved.addListener = tabsOnRemovedAddListenerMock
+    browser.webNavigation.onBeforeNavigate.addListener = webNavigationOnBeforeNavigateAddListenerMock
+    browser.webNavigation.onCompleted.addListener = webNavigationOnCompletedAddListenerMock
+    browser.webNavigation.getAllFrames = getAllFramesMock
+    browser.scripting.executeScript = executeScriptMock
+    storage.getItem = storageGetItemMock
+
     getLocalConfigMock.mockResolvedValue(null)
     getAllFramesMock.mockResolvedValue([
       createFrame(0, "https://example.com/app", -1),
       createFrame(2, "https://example.com/frame"),
     ])
+    storageGetItemMock.mockResolvedValue({ enabled: true })
     executeScriptMock.mockResolvedValue(undefined)
   })
 
+  it("skips iframe injection when page translation is not enabled", async () => {
+    const { onCompleted } = await setupSubject()
+    storageGetItemMock.mockResolvedValue({ enabled: false })
+
+    await onCompleted(createDetails())
+
+    expect(getAllFramesMock).not.toHaveBeenCalled()
+    expect(executeScriptMock).not.toHaveBeenCalled()
+  })
+
   it("injects each document once and targets documentIds when available", async () => {
     const { onCompleted } = await setupSubject()
     const details = createDetails()
@@ -124,7 +116,7 @@ describe("setupIframeInjection", () => {
     await onCompleted(details)
     await onCompleted(details)
 
-    expect(executeScriptMock).toHaveBeenCalledTimes(3)
+    expect(executeScriptMock).toHaveBeenCalledTimes(2)
     expect(executeScriptMock).toHaveBeenNthCalledWith(1, expect.objectContaining({
       target: { tabId: currentTabId, documentIds: ["doc-1"] },
       func: expect.any(Function),
@@ -141,7 +133,7 @@ describe("setupIframeInjection", () => {
 
     await onCompleted(createDetails({ documentId: undefined }))
 
-    expect(executeScriptMock).toHaveBeenCalledTimes(3)
+    expect(executeScriptMock).toHaveBeenCalledTimes(2)
     for (const [call] of executeScriptMock.mock.calls) {
       expect(call.target).toEqual({ tabId: currentTabId, frameIds: [2] })
     }
@@ -153,12 +145,12 @@ describe("setupIframeInjection", () => {
 
     await onCompleted(details)
     await onCompleted(details)
-    expect(executeScriptMock).toHaveBeenCalledTimes(3)
+    expect(executeScriptMock).toHaveBeenCalledTimes(2)
 
     onBeforeNavigate({ tabId: currentTabId, frameId: 2 })
     await onCompleted(details)
 
-    expect(executeScriptMock).toHaveBeenCalledTimes(6)
+    expect(executeScriptMock).toHaveBeenCalledTimes(4)
   })
 
   it("prunes injected records for frames that are no longer live", async () => {
@@ -194,10 +186,10 @@ describe("setupIframeInjection", () => {
       url: "https://example.com/old-frame",
     }))
 
-    expect(executeScriptMock).toHaveBeenCalledTimes(9)
+    expect(executeScriptMock).toHaveBeenCalledTimes(6)
     expect(executeScriptMock).toHaveBeenLastCalledWith(expect.objectContaining({
       target: { tabId: currentTabId, documentIds: ["doc-stale"] },
-      files: ["/content-scripts/selection.js"],
+      files: ["/content-scripts/host.js"],
     }))
   })
 
@@ -207,14 +199,14 @@ describe("setupIframeInjection", () => {
 
     await onCompleted(details)
     await onCompleted(details)
-    expect(executeScriptMock).toHaveBeenCalledTimes(3)
+    expect(executeScriptMock).toHaveBeenCalledTimes(2)
 
     onBeforeNavigate({ tabId: currentTabId, frameId: 0 })
     await onCompleted(details)
-    expect(executeScriptMock).toHaveBeenCalledTimes(6)
+    expect(executeScriptMock).toHaveBeenCalledTimes(4)
 
     onRemoved(currentTabId)
     await onCompleted(details)
-    expect(executeScriptMock).toHaveBeenCalledTimes(9)
+    expect(executeScriptMock).toHaveBeenCalledTimes(6)
   })
 })

src/entrypoints/background/__tests__/translation-signal.test.ts

@@ -0,0 +1,129 @@
+import { browser, storage } from "#imports"
+import { beforeEach, describe, expect, it, vi } from "vitest"
+import { getTranslationStateKey } from "@/utils/constants/storage-keys"
+
+const sendMessageMock = vi.fn()
+const onMessageMock = vi.fn()
+const storageGetItemMock = vi.fn()
+const storageSetItemMock = vi.fn()
+const storageRemoveItemMock = vi.fn()
+const tabsOnRemovedAddListenerMock = vi.fn()
+const webNavigationOnCommittedAddListenerMock = vi.fn()
+const injectHostContentIntoTabIframesMock = vi.fn()
+const loggerErrorMock = vi.fn()
+const loggerWarnMock = vi.fn()
+const shouldEnableAutoTranslationMock = vi.fn()
+
+const messageHandlers = new Map<string, (msg: any) => any>()
+
+vi.mock("@/utils/message", () => ({
+  onMessage: onMessageMock,
+  sendMessage: sendMessageMock,
+}))
+
+vi.mock("@/utils/host/translate/auto-translation", () => ({
+  shouldEnableAutoTranslation: shouldEnableAutoTranslationMock,
+}))
+
+vi.mock("@/utils/logger", () => ({
+  logger: {
+    error: loggerErrorMock,
+    warn: loggerWarnMock,
+  },
+}))
+
+vi.mock("../iframe-injection", () => ({
+  injectHostContentIntoTabIframes: injectHostContentIntoTabIframesMock,
+}))
+
+function getHandler(name: string) {
+  const handler = messageHandlers.get(name)
+  if (!handler) {
+    throw new Error(`Expected message handler to be registered: ${name}`)
+  }
+  return handler
+}
+
+async function setupSubject() {
+  const { translationMessage } = await import("../translation-signal")
+  translationMessage()
+}
+
+describe("translationMessage", () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    messageHandlers.clear()
+
+    browser.tabs.onRemoved.addListener = tabsOnRemovedAddListenerMock
+    browser.webNavigation.onCommitted.addListener = webNavigationOnCommittedAddListenerMock
+    storage.getItem = storageGetItemMock
+    storage.setItem = storageSetItemMock
+    storage.removeItem = storageRemoveItemMock
+
+    onMessageMock.mockImplementation((name: string, handler: (msg: any) => any) => {
+      messageHandlers.set(name, handler)
+      return vi.fn()
+    })
+    sendMessageMock.mockResolvedValue(undefined)
+    storageGetItemMock.mockResolvedValue(undefined)
+    storageSetItemMock.mockResolvedValue(undefined)
+    storageRemoveItemMock.mockResolvedValue(undefined)
+    shouldEnableAutoTranslationMock.mockResolvedValue(false)
+  })
+
+  it("persists manager-enabled state and injects current iframes from the top frame", async () => {
+    await setupSubject()
+
+    await getHandler("setAndNotifyPageTranslationStateChangedByManager")({
+      data: { enabled: true },
+      sender: { tab: { id: 42 }, frameId: 0 },
+    })
+
+    expect(storageSetItemMock).toHaveBeenCalledWith(getTranslationStateKey(42), { enabled: true })
+    expect(sendMessageMock).toHaveBeenCalledWith("notifyTranslationStateChanged", { enabled: true }, 42)
+    expect(injectHostContentIntoTabIframesMock).toHaveBeenCalledWith(42)
+  })
+
+  it("does not reinject every iframe when an iframe manager echoes enabled state", async () => {
+    await setupSubject()
+
+    await getHandler("setAndNotifyPageTranslationStateChangedByManager")({
+      data: { enabled: true },
+      sender: { tab: { id: 42 }, frameId: 7 },
+    })
+
+    expect(storageSetItemMock).toHaveBeenCalledWith(getTranslationStateKey(42), { enabled: true })
+    expect(sendMessageMock).toHaveBeenCalledWith("notifyTranslationStateChanged", { enabled: true }, 42)
+    expect(injectHostContentIntoTabIframesMock).not.toHaveBeenCalled()
+  })
+
+  it("clears state immediately when a tab-level request disables page translation", async () => {
+    await setupSubject()
+
+    await getHandler("tryToSetEnablePageTranslationByTabId")({
+      data: { tabId: 42, enabled: false },
+    })
+
+    expect(storageSetItemMock).toHaveBeenCalledWith(getTranslationStateKey(42), { enabled: false })
+    expect(sendMessageMock).toHaveBeenCalledWith("notifyTranslationStateChanged", { enabled: false }, 42)
+    expect(sendMessageMock).toHaveBeenCalledWith("askManagerToTogglePageTranslation", {
+      enabled: false,
+      analyticsContext: undefined,
+    }, 42)
+  })
+
+  it("waits for the top-frame manager to validate before enabling iframe injection", async () => {
+    await setupSubject()
+
+    await getHandler("tryToSetEnablePageTranslationByTabId")({
+      data: { tabId: 42, enabled: true },
+    })
+
+    expect(storageSetItemMock).not.toHaveBeenCalled()
+    expect(injectHostContentIntoTabIframesMock).not.toHaveBeenCalled()
+    expect(sendMessageMock).toHaveBeenCalledWith("askManagerToTogglePageTranslation", {
+      enabled: true,
+      analyticsContext: undefined,
+    }, 42)
+  })
+})

src/entrypoints/background/context-menu.ts

@@ -7,6 +7,7 @@ import { CONFIG_STORAGE_KEY } from "@/utils/constants/config"
 import { getTranslationStateKey, TRANSLATION_STATE_KEY_PREFIX } from "@/utils/constants/storage-keys"
 import { sendMessage } from "@/utils/message"
 import { ensureInitializedConfig } from "./config"
+import { getPageTranslationEnabled, setPageTranslationEnabled } from "./page-translation-state"
 
 export const MENU_ID_TRANSLATE = "read-frog-translate"
 export const MENU_ID_SELECTION_TRANSLATE = "read-frog-selection-translate"
@@ -194,14 +195,13 @@ async function handleContextMenuClick(
  * Handle translate menu click - toggle page translation
  */
 async function handleTranslateClick(tabId: number) {
-  const state = await storage.getItem<{ enabled: boolean }>(
-    getTranslationStateKey(tabId),
-  )
-  const isCurrentlyTranslated = state?.enabled ?? false
+  const isCurrentlyTranslated = await getPageTranslationEnabled(tabId)
   const newState = !isCurrentlyTranslated
 
-  // Update storage directly (instead of sending message to self)
-  await storage.setItem(getTranslationStateKey(tabId), { enabled: newState })
+  if (!newState) {
+    await setPageTranslationEnabled(tabId, false)
+    void sendMessage("notifyTranslationStateChanged", { enabled: false }, tabId)
+  }
 
   // Notify content script in that specific tab
   void sendMessage("askManagerToTogglePageTranslation", {
@@ -212,7 +212,7 @@ async function handleTranslateClick(tabId: number) {
   }, tabId)
 
   // Update menu title immediately
-  await updateTranslateMenuTitle(tabId)
+  await updateTranslateMenuTitle(tabId, newState)
 }
 
 async function handleSelectionTranslateClick(

src/entrypoints/background/iframe-injection.ts

@@ -1,19 +1,27 @@
+import type { FrameInfoForSiteControl } from "./iframe-injection-utils"
+import type { Config } from "@/types/config/config"
 import { browser } from "#imports"
 import { getLocalConfig } from "@/utils/config/storage"
 import { logger } from "@/utils/logger"
 import { isSiteEnabled, SITE_CONTROL_URL_WINDOW_KEY } from "@/utils/site-control"
 import { resolveSiteControlUrl } from "./iframe-injection-utils"
+import { getPageTranslationEnabled } from "./page-translation-state"
 
 const pendingDocumentKeys = new Set<string>()
 const injectedDocumentKeysByFrame = new Map<string, string>()
 
-function getDocumentInjectionKey(details: { tabId: number, frameId: number, documentId?: string }) {
-  // Gracefully skip document-level deduplication when Chromium does not expose documentId.
-  if (!details.documentId) {
-    return null
-  }
+interface FrameInjectionDetails {
+  tabId: number
+  frameId: number
+  documentId?: string
+  parentFrameId?: number
+  url?: string
+}
 
-  return `${details.tabId}:${details.frameId}:${details.documentId}`
+function getDocumentInjectionKey(details: FrameInjectionDetails) {
+  // documentId is best, but getAllFrames may not expose it. Fall back to URL so
+  // explicit per-tab injections still dedupe until the frame navigates.
+  return `${details.tabId}:${details.frameId}:${details.documentId ?? details.url ?? "unknown"}`
 }
 
 function getFrameInjectionKey(details: { tabId: number, frameId: number }) {
@@ -63,7 +71,7 @@ function setInjectedSiteControlUrl(propertyName: string, siteControlUrl: string)
   ;(globalThis as Record<string, unknown>)[propertyName] = siteControlUrl
 }
 
-function getInjectionTarget(details: { tabId: number, frameId: number, documentId?: string }) {
+function getInjectionTarget(details: FrameInjectionDetails) {
   if (details.documentId) {
     return { tabId: details.tabId, documentIds: [details.documentId] }
   }
@@ -71,6 +79,119 @@ function getInjectionTarget(details: { tabId: number, frameId: number, documentI
   return { tabId: details.tabId, frameIds: [details.frameId] }
 }
 
+async function getFrameSnapshot(tabId: number): Promise<FrameInfoForSiteControl[]> {
+  return await browser.webNavigation.getAllFrames({ tabId }) ?? []
+}
+
+async function injectHostContentIntoFrame(
+  details: FrameInjectionDetails,
+  frames?: FrameInfoForSiteControl[],
+  existingConfig?: Config | null,
+) {
+  const frameKey = getFrameInjectionKey(details)
+  const documentKey = getDocumentInjectionKey(details)
+
+  if (
+    pendingDocumentKeys.has(documentKey)
+    || injectedDocumentKeysByFrame.get(frameKey) === documentKey
+  ) {
+    return
+  }
+
+  pendingDocumentKeys.add(documentKey)
+
+  try {
+    let siteControlUrl: string | undefined
+
+    try {
+      const [config, frameSnapshot] = await Promise.all([
+        existingConfig === undefined ? getLocalConfig() : Promise.resolve(existingConfig),
+        frames === undefined ? getFrameSnapshot(details.tabId) : Promise.resolve(frames),
+      ])
+      const liveFrameIds = new Set(frameSnapshot.map(frame => frame.frameId))
+      liveFrameIds.add(details.frameId)
+      pruneInjectedFrames(details.tabId, liveFrameIds)
+
+      siteControlUrl = resolveSiteControlUrl(
+        details.frameId,
+        details.url,
+        frameSnapshot,
+        getParentFrameIdHint(details),
+      )
+
+      if (!siteControlUrl || !isSiteEnabled(siteControlUrl, config)) {
+        return
+      }
+    }
+    catch (error) {
+      logger.error("[Background][IframeInjection] Failed to resolve iframe injection prerequisites", error)
+      return
+    }
+
+    try {
+      const target = getInjectionTarget(details) as Parameters<typeof browser.scripting.executeScript>[0]["target"]
+
+      await browser.scripting.executeScript({
+        target,
+        func: setInjectedSiteControlUrl,
+        args: [SITE_CONTROL_URL_WINDOW_KEY, siteControlUrl],
+      })
+
+      await browser.scripting.executeScript({
+        target,
+        files: ["/content-scripts/host.js"],
+      })
+
+      injectedDocumentKeysByFrame.set(frameKey, documentKey)
+    }
+    catch (error) {
+      logger.warn("[Background][IframeInjection] Failed to inject iframe content scripts", error)
+    }
+  }
+  finally {
+    pendingDocumentKeys.delete(documentKey)
+  }
+}
+
+export async function injectHostContentIntoTabIframes(tabId: number) {
+  let isEnabled: boolean
+  try {
+    isEnabled = await getPageTranslationEnabled(tabId)
+  }
+  catch (error) {
+    logger.warn("[Background][IframeInjection] Failed to read page translation state", error)
+    return
+  }
+
+  if (!isEnabled)
+    return
+
+  let config: Config | null
+  let frames: FrameInfoForSiteControl[]
+  try {
+    [config, frames] = await Promise.all([
+      getLocalConfig(),
+      getFrameSnapshot(tabId),
+    ])
+  }
+  catch (error) {
+    logger.error("[Background][IframeInjection] Failed to resolve tab iframe injection prerequisites", error)
+    return
+  }
+
+  const liveFrameIds = new Set(frames.map(frame => frame.frameId))
+  pruneInjectedFrames(tabId, liveFrameIds)
+
+  await Promise.all(frames
+    .filter(frame => frame.frameId !== 0)
+    .map(frame => injectHostContentIntoFrame({
+      tabId,
+      frameId: frame.frameId,
+      parentFrameId: frame.parentFrameId,
+      url: frame.url,
+    }, frames, config)))
+}
+
 export function setupIframeInjection() {
   browser.tabs.onRemoved.addListener(clearTabDocumentState)
   browser.webNavigation.onBeforeNavigate.addListener((details) => {
@@ -82,86 +203,24 @@ export function setupIframeInjection() {
     clearFrameInjectedDocumentState(details.tabId, details.frameId)
   })
 
-  // Listen for iframe loads and inject content scripts programmatically
-  // This catches iframes that Chrome's manifest-based all_frames: true misses
-  // (e.g., dynamically created iframes, sandboxed iframes like edX)
+  // Only inject into subframes after page translation is enabled for the tab.
+  // This keeps iframe-heavy pages and benchmarks from paying content-script cost
+  // before the feature is actually used.
   browser.webNavigation.onCompleted.addListener(async (details) => {
     // Skip main frame (frameId === 0), only handle iframes
     if (details.frameId === 0)
       return
 
-    const frameKey = getFrameInjectionKey(details)
-    const documentKey = getDocumentInjectionKey(details)
-    if (documentKey) {
-      if (
-        pendingDocumentKeys.has(documentKey)
-        || injectedDocumentKeysByFrame.get(frameKey) === documentKey
-      ) {
-        return
-      }
-
-      pendingDocumentKeys.add(documentKey)
-    }
-
     try {
-      let siteControlUrl: string | undefined
-
-      try {
-        const config = await getLocalConfig()
-        const frames = await browser.webNavigation.getAllFrames({ tabId: details.tabId }) ?? []
-        const liveFrameIds = new Set(frames.map(frame => frame.frameId))
-        liveFrameIds.add(details.frameId)
-        pruneInjectedFrames(details.tabId, liveFrameIds)
-
-        siteControlUrl = resolveSiteControlUrl(
-          details.frameId,
-          details.url,
-          frames,
-          getParentFrameIdHint(details),
-        )
-
-        if (!siteControlUrl || !isSiteEnabled(siteControlUrl, config)) {
-          return
-        }
-      }
-      catch (error) {
-        logger.error("[Background][IframeInjection] Failed to resolve iframe injection prerequisites", error)
+      const isEnabled = await getPageTranslationEnabled(details.tabId)
+      if (!isEnabled)
         return
-      }
-
-      try {
-        const target = getInjectionTarget(details) as Parameters<typeof browser.scripting.executeScript>[0]["target"]
-
-        await browser.scripting.executeScript({
-          target,
-          func: setInjectedSiteControlUrl,
-          args: [SITE_CONTROL_URL_WINDOW_KEY, siteControlUrl],
-        })
-
-        // Inject host.content script into the iframe
-        await browser.scripting.executeScript({
-          target,
-          files: ["/content-scripts/host.js"],
-        })
-
-        // Inject selection.content script into the iframe
-        await browser.scripting.executeScript({
-          target,
-          files: ["/content-scripts/selection.js"],
-        })
-
-        if (documentKey) {
-          injectedDocumentKeysByFrame.set(frameKey, documentKey)
-        }
-      }
-      catch (error) {
-        logger.warn("[Background][IframeInjection] Failed to inject iframe content scripts", error)
-      }
     }
-    finally {
-      if (documentKey) {
-        pendingDocumentKeys.delete(documentKey)
-      }
+    catch (error) {
+      logger.warn("[Background][IframeInjection] Failed to read page translation state", error)
+      return
     }
+
+    await injectHostContentIntoFrame(details)
   })
 }

src/entrypoints/background/index.ts

@@ -109,7 +109,7 @@ export default defineBackground({
     setupTTSPlaybackMessageHandlers()
     void initMockData()
 
-    // Setup programmatic injection for iframes that Chrome's manifest-based all_frames misses
+    // Setup on-demand iframe injection after page translation is enabled.
     setupIframeInjection()
   },
 })

src/entrypoints/background/page-translation-state.ts

@@ -0,0 +1,17 @@
+import type { TranslationState } from "@/types/translation-state"
+import { storage } from "#imports"
+import { getTranslationStateKey } from "@/utils/constants/storage-keys"
+
+export async function getPageTranslationEnabled(tabId: number): Promise<boolean> {
+  const state = await storage.getItem<TranslationState>(
+    getTranslationStateKey(tabId),
+  )
+  return state?.enabled ?? false
+}
+
+export async function setPageTranslationEnabled(tabId: number, enabled: boolean): Promise<void> {
+  await storage.setItem<TranslationState>(
+    getTranslationStateKey(tabId),
+    { enabled },
+  )
+}

src/entrypoints/background/translation-signal.ts

@@ -1,5 +1,5 @@
+import type { FeatureUsageContext } from "@/types/analytics"
 import type { Config } from "@/types/config/config"
-import type { TranslationState } from "@/types/translation-state"
 import { browser, storage } from "#imports"
 import { ANALYTICS_FEATURE, ANALYTICS_SURFACE } from "@/types/analytics"
 import { createFeatureUsageContext } from "@/utils/analytics"
@@ -8,6 +8,22 @@ import { getTranslationStateKey } from "@/utils/constants/storage-keys"
 import { shouldEnableAutoTranslation } from "@/utils/host/translate/auto-translation"
 import { logger } from "@/utils/logger"
 import { onMessage, sendMessage } from "@/utils/message"
+import { injectHostContentIntoTabIframes } from "./iframe-injection"
+import { getPageTranslationEnabled, setPageTranslationEnabled } from "./page-translation-state"
+
+function notifyPageTranslationStateChanged(tabId: number, enabled: boolean) {
+  void sendMessage("notifyTranslationStateChanged", { enabled }, tabId)
+    .catch(error => logger.warn("Failed to notify page translation state change", error))
+}
+
+function requestManagerToTogglePageTranslation(
+  tabId: number,
+  enabled: boolean,
+  analyticsContext?: FeatureUsageContext,
+) {
+  void sendMessage("askManagerToTogglePageTranslation", { enabled, analyticsContext }, tabId)
+    .catch(error => logger.warn("Failed to ask page translation manager to toggle", error))
+}
 
 export function translationMessage() {
   onMessage("getEnablePageTranslationByTabId", async (msg) => {
@@ -26,7 +42,11 @@ export function translationMessage() {
 
   onMessage("tryToSetEnablePageTranslationByTabId", async (msg) => {
     const { tabId, enabled, analyticsContext } = msg.data
-    void sendMessage("askManagerToTogglePageTranslation", { enabled, analyticsContext }, tabId)
+    if (!enabled) {
+      await setPageTranslationEnabled(tabId, false)
+      notifyPageTranslationStateChanged(tabId, false)
+    }
+    requestManagerToTogglePageTranslation(tabId, enabled, analyticsContext)
   })
 
   onMessage("tryToSetEnablePageTranslationOnContentScript", async (msg) => {
@@ -34,7 +54,11 @@ export function translationMessage() {
     const { enabled, analyticsContext } = msg.data
     if (typeof tabId === "number") {
       logger.info("sending tryToSetEnablePageTranslationOnContentScript to manager", { enabled, tabId })
-      await sendMessage("askManagerToTogglePageTranslation", { enabled, analyticsContext }, tabId)
+      if (!enabled) {
+        await setPageTranslationEnabled(tabId, false)
+        notifyPageTranslationStateChanged(tabId, false)
+      }
+      requestManagerToTogglePageTranslation(tabId, enabled, analyticsContext)
     }
     else {
       logger.error("tabId is not a number", msg)
@@ -50,10 +74,11 @@ export function translationMessage() {
         return
       const shouldEnable = await shouldEnableAutoTranslation(url, detectedCodeOrUnd, config)
       if (shouldEnable) {
-        void sendMessage("askManagerToTogglePageTranslation", {
-          enabled: true,
-          analyticsContext: createFeatureUsageContext(ANALYTICS_FEATURE.PAGE_TRANSLATION, ANALYTICS_SURFACE.PAGE_AUTO),
-        }, tabId)
+        requestManagerToTogglePageTranslation(
+          tabId,
+          true,
+          createFeatureUsageContext(ANALYTICS_FEATURE.PAGE_TRANSLATION, ANALYTICS_SURFACE.PAGE_AUTO),
+        )
       }
     }
   })
@@ -62,11 +87,13 @@ export function translationMessage() {
     const tabId = msg.sender?.tab?.id
     const { enabled } = msg.data
     if (typeof tabId === "number") {
-      await storage.setItem<TranslationState>(
-        getTranslationStateKey(tabId),
-        { enabled },
-      )
-      void sendMessage("notifyTranslationStateChanged", { enabled }, tabId)
+      await setPageTranslationEnabled(tabId, enabled)
+      notifyPageTranslationStateChanged(tabId, enabled)
+
+      const senderFrameId = msg.sender?.frameId
+      if (enabled && (senderFrameId === 0 || senderFrameId === undefined)) {
+        void injectHostContentIntoTabIframes(tabId)
+      }
     }
     else {
       logger.error("tabId is not a number", msg)
@@ -75,10 +102,7 @@ export function translationMessage() {
 
   // === Helper Functions ===
   async function getTranslationState(tabId: number): Promise<boolean> {
-    const state = await storage.getItem<TranslationState>(
-      getTranslationStateKey(tabId),
-    )
-    return state?.enabled ?? false
+    return await getPageTranslationEnabled(tabId)
   }
 
   // === Cleanup ===

src/entrypoints/host.content/index.tsx

@@ -12,7 +12,6 @@ declare global {
 export default defineContentScript({
   matches: ["*://*/*", "file:///*"],
   cssInjectionMode: "manual",
-  allFrames: true,
   async main(ctx) {
     // Prevent double injection (manifest-based + programmatic injection)
     if (window.__READ_FROG_HOST_INJECTED__)

src/entrypoints/host.content/runtime.ts

@@ -78,6 +78,15 @@ export async function bootstrapHostContent(ctx: ContentScriptContext, initialCon
     enabled ? void manager.start(window === window.top ? analyticsContext : undefined) : manager.stop()
   })
 
+  const cleanupFrameTranslationStateListener = window === window.top
+    ? () => {}
+    : onMessage("notifyTranslationStateChanged", (msg) => {
+        const { enabled } = msg.data
+        if (enabled === manager.isActive)
+          return
+        enabled ? void manager.start() : manager.stop()
+      })
+
   ctx.onInvalidated(() => {
     removeHostToast()
     cleanupUrlListener()
@@ -85,6 +94,7 @@ export async function bootstrapHostContent(ctx: ContentScriptContext, initialCon
     cleanupPageTranslationTriggers()
     cleanupTranslationShortcut()
     cleanupTranslationStateListener()
+    cleanupFrameTranslationStateListener()
     window.removeEventListener("extension:URLChange", handleExtensionUrlChange)
     window.__READ_FROG_HOST_INJECTED__ = false
     clearEffectiveSiteControlUrl()

src/entrypoints/selection.content/index.tsx

@@ -85,7 +85,6 @@ async function mountSelectionUI(ctx: ContentScriptContext) {
 export default defineContentScript({
   matches: ["*://*/*", "file:///*"],
   cssInjectionMode: "ui",
-  allFrames: true,
   async main(ctx) {
     // Prevent double injection (manifest-based + programmatic injection)
     if (window.__READ_FROG_SELECTION_INJECTED__)