fix(browser): debounce find-in-page query to stop per-keystroke flash (#836)

* fix(browser): debounce find-in-page query to stop per-keystroke flash

Why: findInPage re-highlights the active match on every call, which flashed
as the user typed. Debounce (200ms) so the highlight only re-runs once typing
settles. Enter still uses the live query for immediate next/previous nav.

* fix(browser): auto-select top suggestion, preserve address-bar typing

- Top history suggestion is auto-selected so Enter navigates to the best
  match without an extra ArrowDown keypress.
- URL syncs from the store and webview navigation events no longer clobber
  the address bar while the user is actively typing in it. Previously,
  opening a fresh tab and starting to type could be overridden when the
  configured default URL (e.g. google.com) finished resolving.

src/renderer/src/components/browser-pane/BrowserAddressBar.tsx

@@ -162,8 +162,11 @@ export default function BrowserAddressBar({
     }
   }, [open, suggestions.length])
 
+  // Why: auto-select the top suggestion so Enter navigates to the best match
+  // without an extra ArrowDown. Fall back to clearing selection when nothing
+  // matches so stale highlights don't persist.
   useEffect(() => {
-    setSelectedValue('')
+    setSelectedValue(suggestions[0]?.url ?? '')
   }, [suggestions])
 
   return (

src/renderer/src/components/browser-pane/BrowserFind.tsx

@@ -15,9 +15,19 @@ export default function BrowserFind({
 }: BrowserFindProps): React.JSX.Element | null {
   const inputRef = useRef<HTMLInputElement>(null)
   const [query, setQuery] = useState('')
+  const [debouncedQuery, setDebouncedQuery] = useState('')
   const [activeMatch, setActiveMatch] = useState(0)
   const [totalMatches, setTotalMatches] = useState(0)
 
+  // Why: findInPage re-highlights the active match on every call, which causes
+  // a visible flash as the user types. Debounce to only re-run once typing
+  // settles. Enter (findNext/findPrevious) still uses the live `query` so
+  // explicit navigation is immediate.
+  useEffect(() => {
+    const id = setTimeout(() => setDebouncedQuery(query), 200)
+    return () => clearTimeout(id)
+  }, [query])
+
   const safeFindInPage = useCallback(
     (text: string, opts?: Electron.FindInPageOptions): void => {
       const webview = webviewRef.current
@@ -70,16 +80,16 @@ export default function BrowserFind({
   }, [isOpen, safeStopFindInPage])
 
   useEffect(() => {
-    if (!query) {
+    if (!debouncedQuery) {
       safeStopFindInPage()
       setActiveMatch(0)
       setTotalMatches(0)
       return
     }
     if (isOpen) {
-      safeFindInPage(query)
+      safeFindInPage(debouncedQuery)
     }
-  }, [query, isOpen, safeFindInPage, safeStopFindInPage])
+  }, [debouncedQuery, isOpen, safeFindInPage, safeStopFindInPage])
 
   // Why: this effect captures `webviewRef.current` into a local variable, so
   // if the webview element were replaced while `isOpen` stays true the listener

src/renderer/src/components/browser-pane/BrowserPane.tsx

@@ -505,6 +505,13 @@ function BrowserPagePane({
   }, [browserTab.id, browserTab.url])
 
   useEffect(() => {
+    // Why: if the user is actively typing in the address bar (focused), do not
+    // clobber their in-progress query when an async URL update lands (e.g., the
+    // configured default URL resolving after a new tab opens). Syncing will
+    // resume on the next legitimate URL change after the input loses focus.
+    if (document.activeElement === addressBarInputRef.current) {
+      return
+    }
     setAddressBarValue(toDisplayUrl(browserTab.url))
   }, [browserTab.url])
 
@@ -1056,7 +1063,11 @@ function BrowserPagePane({
       activeLoadFailureRef.current = null
       lastKnownWebviewUrlRef.current = normalizeBrowserNavigationUrl(currentUrl) ?? currentUrl
       rememberLiveBrowserUrl(browserTab.id, currentUrl)
-      setAddressBarValue(toDisplayUrl(currentUrl))
+      // Why: don't overwrite in-progress typing. See comment on the
+      // browserTab.url sync effect above.
+      if (document.activeElement !== addressBarInputRef.current) {
+        setAddressBarValue(toDisplayUrl(currentUrl))
+      }
       onSetUrlRef.current(browserTab.id, currentUrl)
       if (keepAddressBarFocusRef.current && currentUrl === ORCA_BROWSER_BLANK_URL) {
         focusAddressBarNow()
@@ -1083,7 +1094,10 @@ function BrowserPagePane({
       }
       lastKnownWebviewUrlRef.current = normalizeBrowserNavigationUrl(currentUrl) ?? currentUrl
       rememberLiveBrowserUrl(browserTab.id, currentUrl)
-      setAddressBarValue(toDisplayUrl(currentUrl))
+      // Why: don't overwrite in-progress typing (see above).
+      if (document.activeElement !== addressBarInputRef.current) {
+        setAddressBarValue(toDisplayUrl(currentUrl))
+      }
       onSetUrlRef.current(browserTab.id, currentUrl)
       onUpdatePageStateRef.current(browserTab.id, {
         title: webview.getTitle() || currentUrl,