perf: replace useSearchParams() with window.location.search in effects

Components were calling useSearchParams() at the top level but only
reading the value inside useEffect or callbacks, never in JSX. This
subscribed the entire component tree to every URL query change.

Fix: read from window.location.search directly inside the effect so
no React subscription is created.

Changes:
- new-chat/page.tsx: read commentId inside effect + popstate listener
  for SPA back/forward support; removes subscription from 1500+ line tree
- dashboard/page.tsx: read window.location.search at redirect time;
  removes searchParams from dep array
- public-chat-footer.tsx: one-shot mount read for action=clone param
- TokenHandler.tsx: one-shot mount read for token + refresh_token params

Implements Vercel React Best Practices Rule: rerender-defer-reads (5.2)

surfsense_web/app/dashboard/[search_space_id]/new-chat/[[...chat_id]]/page.tsx

@@ -8,7 +8,7 @@ import {
 } from "@assistant-ui/react";
 import { useQueryClient } from "@tanstack/react-query";
 import { useAtomValue, useSetAtom } from "jotai";
-import { useParams, useSearchParams } from "next/navigation";
+import { useParams } from "next/navigation";
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { toast } from "sonner";
 import { z } from "zod";
@@ -388,22 +388,32 @@ export default function NewChatPage() {
 	}, [searchSpaceId, queryClient]);
 
 	// Handle scroll to comment from URL query params (e.g., from inbox item click)
-	const searchParams = useSearchParams();
-	const targetCommentIdParam = searchParams.get("commentId");
-
-	// Set target comment ID from URL param - the AssistantMessage and CommentItem
-	// components will handle scrolling and highlighting once comments are loaded
+	// Read from window.location.search inside the effect instead of subscribing via
+	// useSearchParams() — avoids re-rendering this heavy component tree on every
+	// unrelated query-string change. (Vercel Best Practice: rerender-defer-reads 5.2)
 	useEffect(() => {
-		if (targetCommentIdParam && !isInitializing) {
-			const commentId = Number.parseInt(targetCommentIdParam, 10);
-			if (!Number.isNaN(commentId)) {
-				setTargetCommentId(commentId);
+		const readAndApplyCommentId = () => {
+			const params = new URLSearchParams(window.location.search);
+			const raw = params.get("commentId");
+			if (raw && !isInitializing) {
+				const commentId = Number.parseInt(raw, 10);
+				if (!Number.isNaN(commentId)) {
+					setTargetCommentId(commentId);
+				}
 			}
-		}
+		};
+
+		readAndApplyCommentId();
+
+		// Also respond to SPA navigations (back/forward) that change the query string
+		window.addEventListener("popstate", readAndApplyCommentId);
 
 		// Cleanup on unmount or when navigating away
-		return () => clearTargetCommentId();
-	}, [targetCommentIdParam, isInitializing, setTargetCommentId, clearTargetCommentId]);
+		return () => {
+			window.removeEventListener("popstate", readAndApplyCommentId);
+			clearTargetCommentId();
+		};
+	}, [isInitializing, setTargetCommentId, clearTargetCommentId]);
 
 	// Sync current thread state to atom
 	useEffect(() => {

surfsense_web/app/dashboard/page.tsx

@@ -3,7 +3,7 @@
 import { useAtomValue } from "jotai";
 import { AlertCircle, Plus, Search } from "lucide-react";
 import { motion } from "motion/react";
-import { useRouter, useSearchParams } from "next/navigation";
+import { useRouter } from "next/navigation";
 import { useTranslations } from "next-intl";
 import { useEffect, useState } from "react";
 import { searchSpacesAtom } from "@/atoms/search-spaces/search-space-query.atoms";
@@ -89,7 +89,6 @@ function EmptyState({ onCreateClick }: { onCreateClick: () => void }) {
 
 export default function DashboardPage() {
 	const router = useRouter();
-	const searchParams = useSearchParams();
 	const [showCreateDialog, setShowCreateDialog] = useState(false);
 
 	const t = useTranslations("dashboard");
@@ -99,11 +98,12 @@ export default function DashboardPage() {
 		if (isLoading) return;
 
 		if (searchSpaces.length > 0) {
-			const params = searchParams.toString();
-			const query = params ? `?${params}` : "";
+			// Read the query string at the time of redirect — no subscription needed.
+			// (Vercel Best Practice: rerender-defer-reads 5.2)
+			const query = window.location.search;
 			router.replace(`/dashboard/${searchSpaces[0].id}/new-chat${query}`);
 		}
-	}, [isLoading, searchSpaces, router, searchParams]);
+	}, [isLoading, searchSpaces, router]);
 
 	// Show loading while fetching or while we have spaces and are about to redirect
 	const shouldShowLoading = isLoading || searchSpaces.length > 0;

surfsense_web/components/TokenHandler.tsx

@@ -1,6 +1,5 @@
 "use client";
 
-import { useSearchParams } from "next/navigation";
 import { useEffect } from "react";
 import { useGlobalLoadingEffect } from "@/hooks/use-global-loading";
 import { getAndClearRedirectPath, setBearerToken, setRefreshToken } from "@/lib/auth-utils";
@@ -26,8 +25,6 @@ const TokenHandler = ({
 	tokenParamName = "token",
 	storageKey = "surfsense_bearer_token",
 }: TokenHandlerProps) => {
-	const searchParams = useSearchParams();
-
 	// Always show loading for this component - spinner animation won't reset
 	useGlobalLoadingEffect(true);
 
@@ -35,9 +32,13 @@ const TokenHandler = ({
 		// Only run on client-side
 		if (typeof window === "undefined") return;
 
-		// Get tokens from URL parameters
-		const token = searchParams.get(tokenParamName);
-		const refreshToken = searchParams.get("refresh_token");
+		// Read tokens from URL at mount time — no subscription needed.
+		// TokenHandler only runs once after an auth redirect, so a stale read
+		// is impossible and useSearchParams() would add a pointless subscription.
+		// (Vercel Best Practice: rerender-defer-reads 5.2)
+		const params = new URLSearchParams(window.location.search);
+		const token = params.get(tokenParamName);
+		const refreshToken = params.get("refresh_token");
 
 		if (token) {
 			try {
@@ -74,7 +75,7 @@ const TokenHandler = ({
 				window.location.href = redirectPath;
 			}
 		}
-	}, [searchParams, tokenParamName, storageKey, redirectPath]);
+	}, [tokenParamName, storageKey, redirectPath]);
 
 	// Return null - the global provider handles the loading UI
 	return null;

surfsense_web/components/public-chat/public-chat-footer.tsx

@@ -1,7 +1,7 @@
 "use client";
 
 import { Copy } from "lucide-react";
-import { useRouter, useSearchParams } from "next/navigation";
+import { useRouter } from "next/navigation";
 import { useCallback, useEffect, useRef, useState } from "react";
 import { toast } from "sonner";
 import { Button } from "@/components/ui/button";
@@ -15,7 +15,6 @@ interface PublicChatFooterProps {
 
 export function PublicChatFooter({ shareToken }: PublicChatFooterProps) {
 	const router = useRouter();
-	const searchParams = useSearchParams();
 	const [isCloning, setIsCloning] = useState(false);
 	const hasAutoCloned = useRef(false);
 
@@ -36,9 +35,11 @@ export function PublicChatFooter({ shareToken }: PublicChatFooterProps) {
 		}
 	}, [shareToken, router]);
 
-	// Auto-trigger clone if user just logged in with action=clone
+	// Auto-trigger clone if user just logged in with action=clone.
+	// Read from window.location.search on mount — no subscription needed since
+	// this is a one-time post-login check. (Vercel Best Practice: rerender-defer-reads 5.2)
 	useEffect(() => {
-		const action = searchParams.get("action");
+		const action = new URLSearchParams(window.location.search).get("action");
 		const token = getBearerToken();
 
 		// Only auto-clone once, if authenticated and action=clone is present
@@ -46,7 +47,7 @@ export function PublicChatFooter({ shareToken }: PublicChatFooterProps) {
 			hasAutoCloned.current = true;
 			triggerClone();
 		}
-	}, [searchParams, isCloning, triggerClone]);
+	}, [isCloning, triggerClone]);
 
 	const handleCopyAndContinue = async () => {
 		const token = getBearerToken();