fix(lint): move the doc preview guest-focus handoff into its own hook (#28110)

HtmlDocPreview.tsx reached 403 lines on main (#27608 + #27875), over the
400-line limit for .tsx, so lint and the pre-commit hook fail on any
branch that merges main. The focus handoff effect moves unchanged into
use-doc-preview-guest-focus.ts.

Co-authored-by: Orca Worker <orca-worker@localhost>

src/renderer/src/components/browser-pane/workspace-doc/HtmlDocPreview.tsx

@@ -34,12 +34,11 @@ import {
 import { DocPreviewToolbar } from './doc-preview-toolbar'
 import { buildDocPreviewShareControl } from './doc-preview-artifact-share'
 import { useDocPreviewWebviewHistory } from './doc-preview-webview-history'
+import { useDocPreviewGuestFocus } from './use-doc-preview-guest-focus'
 import { useDocPreviewGuestTools } from './use-doc-preview-guest-tools'
 
 type PreviewState = 'loading' | 'ready' | 'unavailable'
 
-/** Frames a preview keeps offering focus to a guest that is still attaching. */
-const GUEST_FOCUS_FRAMES = 10
 const MAX_ASSET_FAILURES = 50
 
 export function HtmlDocPreview({
@@ -301,58 +300,13 @@ export function HtmlDocPreview({
       .recordWorkspaceDocVisit({ kind: 'workspace-doc', worktreeId, filePath }, null)
   }, [filePath, worktreeId])
 
-  // Why the guest is handed focus: a preview has no address bar to make the usual handoff, so a
-  // surfaced document would otherwise look active while its keyboard and link input land elsewhere.
-  useEffect(() => {
-    if (!holdsGuestFocus || state !== 'ready') {
-      return
-    }
-    let frameId = 0
-    let attempts = 0
-    let claimedOnly = false
-    const focusGuest = (): void => {
-      const webview = webviewRef.current
-      attempts += 1
-      // Why a re-offer yields: it is a handoff for focus nothing else wanted, and the reader
-      // pressing a tab lands here first. Taking it back would fight them for the keyboard, which
-      // is what shut the tab strip while a preview was open.
-      if (
-        claimedOnly &&
-        document.activeElement !== document.body &&
-        document.activeElement !== webview
-      ) {
-        return
-      }
-      try {
-        webview?.focus()
-      } catch {
-        // Why swallowed: WebViewElement.focus() reads null internals once the guest is destroyed.
-        return
-      }
-      // Why retried: the guest takes focus only once it is attached and laid out, a frame or two
-      // after it reports ready.
-      if (document.activeElement !== webview && attempts < GUEST_FOCUS_FRAMES) {
-        frameId = window.requestAnimationFrame(focusGuest)
-      }
-    }
-    const offerFocus = (yieldToOtherClaims: boolean): void => {
-      window.cancelAnimationFrame(frameId)
-      attempts = 0
-      claimedOnly = yieldToOtherClaims
-      frameId = window.requestAnimationFrame(focusGuest)
-    }
-    // Why assertive: the reader just made this preview their surface, so the handoff is the point.
-    offerFocus(false)
-    // Why re-offered on the window's own focus: another app taking the front takes focus out of the
-    // guest, and coming back puts it on the embedder. Nothing hands it on, so the route out of the
-    // preview would stay shut until something remounted it.
-    const reofferFocus = (): void => offerFocus(true)
-    window.addEventListener('focus', reofferFocus)
-    return () => {
-      window.removeEventListener('focus', reofferFocus)
-      window.cancelAnimationFrame(frameId)
-    }
-  }, [holdsGuestFocus, previewId, remintCount, state])
+  useDocPreviewGuestFocus({
+    webviewRef,
+    holdsGuestFocus,
+    ready: state === 'ready',
+    previewId,
+    remintCount
+  })
 
   // Why: a grant is pinned to the owner ids resolved when it was minted, so after a pairing or
   // SSH reconnect the old one reads nothing and reloading the guest would just refetch the

src/renderer/src/components/browser-pane/workspace-doc/use-doc-preview-guest-focus.ts

@@ -0,0 +1,74 @@
+import { useEffect, type MutableRefObject } from 'react'
+
+/** Frames a preview keeps offering focus to a guest that is still attaching. */
+const GUEST_FOCUS_FRAMES = 10
+
+/**
+ * Hands a ready preview's guest the keyboard. A preview has no address bar to make the usual
+ * handoff, so a surfaced document would otherwise look active while its keyboard and link input
+ * land elsewhere. `remintCount` re-runs the handoff when a re-mint replaces the guest.
+ */
+export function useDocPreviewGuestFocus({
+  webviewRef,
+  holdsGuestFocus,
+  ready,
+  previewId,
+  remintCount
+}: {
+  webviewRef: MutableRefObject<Electron.WebviewTag | null>
+  holdsGuestFocus: boolean
+  ready: boolean
+  previewId: string
+  remintCount: number
+}): void {
+  useEffect(() => {
+    if (!holdsGuestFocus || !ready) {
+      return
+    }
+    let frameId = 0
+    let attempts = 0
+    let claimedOnly = false
+    const focusGuest = (): void => {
+      const webview = webviewRef.current
+      attempts += 1
+      // Why a re-offer yields: it is a handoff for focus nothing else wanted, and the reader
+      // pressing a tab lands here first. Taking it back would fight them for the keyboard, which
+      // is what shut the tab strip while a preview was open.
+      if (
+        claimedOnly &&
+        document.activeElement !== document.body &&
+        document.activeElement !== webview
+      ) {
+        return
+      }
+      try {
+        webview?.focus()
+      } catch {
+        // Why swallowed: WebViewElement.focus() reads null internals once the guest is destroyed.
+        return
+      }
+      // Why retried: the guest takes focus only once it is attached and laid out, a frame or two
+      // after it reports ready.
+      if (document.activeElement !== webview && attempts < GUEST_FOCUS_FRAMES) {
+        frameId = window.requestAnimationFrame(focusGuest)
+      }
+    }
+    const offerFocus = (yieldToOtherClaims: boolean): void => {
+      window.cancelAnimationFrame(frameId)
+      attempts = 0
+      claimedOnly = yieldToOtherClaims
+      frameId = window.requestAnimationFrame(focusGuest)
+    }
+    // Why assertive: the reader just made this preview their surface, so the handoff is the point.
+    offerFocus(false)
+    // Why re-offered on the window's own focus: another app taking the front takes focus out of the
+    // guest, and coming back puts it on the embedder. Nothing hands it on, so the route out of the
+    // preview would stay shut until something remounted it.
+    const reofferFocus = (): void => offerFocus(true)
+    window.addEventListener('focus', reofferFocus)
+    return () => {
+      window.removeEventListener('focus', reofferFocus)
+      window.cancelAnimationFrame(frameId)
+    }
+  }, [holdsGuestFocus, previewId, ready, remintCount, webviewRef])
+}