feat(nav): add flow-guarding for exam result screens

app/exam/[id]/page.tsx

@@ -1,22 +1,33 @@
 "use client";
 
 import React, { useEffect, useCallback, useState } from "react";
-import { useRouter, useSearchParams } from "next/navigation";
+import { usePathname, useRouter, useSearchParams } from "next/navigation";
 import Header from "@/components/Header";
 import QuestionItem from "@/components/QuestionItem";
 import BackgroundWrapper from "@/components/BackgroundWrapper";
 import { useExamStore } from "@/stores/examStore";
 import { useTimerStore } from "@/stores/timerStore";
+import { useExamExitGuard } from "@/hooks/useExamExitGuard";
 
 export default function ExamPage() {
   const router = useRouter();
+  const pathname = usePathname();
   const searchParams = useSearchParams();
   const test_id = searchParams.get("test_id") || "";
   const type = searchParams.get("type") || "";
 
-  const { test, answers, startExam, setAnswer, submitExam, cancelExam } =
+  const {
-    useExamStore();
+    setStatus,
+    test,
+    answers,
+    startExam,
+    setAnswer,
+    submitExam,
+    cancelExam,
+    status,
+  } = useExamStore();
   const { resetTimer, stopTimer } = useTimerStore();
+  const { showExitDialog } = useExamExitGuard(type);
 
   const [isSubmitting, setIsSubmitting] = useState(false);
 
@@ -25,24 +36,52 @@ export default function ExamPage() {
     if (type && test_id) {
       startExam(type, test_id).then((fetchedTest) => {
         if (fetchedTest?.metadata.time_limit_minutes) {
+          setStatus("in-progress"); // ✅ make sure exam status is set here
           resetTimer(fetchedTest.metadata.time_limit_minutes * 60, () => {
-            // Timer ended → auto-submit exam
+            // Timer ended → auto-submit
+            setStatus("finished");
             stopTimer();
             submitExam(type);
-            router.push(`/exam/results`);
+            router.replace(`/exam/results`);
           });
         }
       });
     }
-  }, [type, test_id, startExam, resetTimer, submitExam, router]);
+  }, [
+    type,
+    test_id,
+    startExam,
+    resetTimer,
+    submitExam,
+    router,
+    setStatus,
+    stopTimer,
+  ]);
 
-  const showExitDialog = useCallback(() => {
+  // useEffect(() => {
-    if (window.confirm("Are you sure you want to quit the exam?")) {
+  //   const handlePopState = (event: PopStateEvent) => {
-      stopTimer();
+  //     if (status === "in-progress") {
-      cancelExam();
+  //       const confirmExit = window.confirm(
-      router.push(`/categories/${type}s`);
+  //         "Are you sure you want to quit the exam?"
-    }
+  //       );
-  }, [stopTimer, cancelExam, router, type]);
+
+  //       if (confirmExit) {
+  //         setStatus("finished");
+  //         stopTimer();
+  //         cancelExam();
+  //         router.replace(`/categories/${type}s`);
+  //       } else {
+  //         // User canceled → push them back to current page
+  //         router.replace(pathname, { scroll: false });
+  //       }
+  //     } else {
+  //       router.replace(`/categories/${type}s`);
+  //     }
+  //   };
+
+  //   window.addEventListener("popstate", handlePopState);
+  //   return () => window.removeEventListener("popstate", handlePopState);
+  // }, [status, router, pathname, type, setStatus, stopTimer, cancelExam]);
 
   if (!test) {
     return (
@@ -57,10 +96,11 @@ export default function ExamPage() {
 
   const handleSubmitExam = async (type: string) => {
     try {
+      setStatus("finished"); // ✅ mark exam finished
       stopTimer();
       setIsSubmitting(true);
       await submitExam(type);
-      router.push(`/exam/results`);
+      router.replace(`/exam/results`); // ✅ replace to prevent back nav
     } finally {
       setIsSubmitting(false);
     }

app/exam/pretest/page.tsx

@@ -13,7 +13,6 @@ import {
 import DestructibleAlert from "@/components/DestructibleAlert";
 import BackgroundWrapper from "@/components/BackgroundWrapper";
 import { API_URL, getToken } from "@/lib/auth";
-import { useExam } from "@/context/ExamContext";
 import { Test } from "@/types/exam";
 import { Metadata } from "@/types/exam";
 import { useExamStore } from "@/stores/examStore";
@@ -21,7 +20,7 @@ import { useExamStore } from "@/stores/examStore";
 function PretestPageContent() {
   const router = useRouter();
   const searchParams = useSearchParams();
-  const { startExam } = useExamStore();
+
   const [examData, setExamData] = useState<Test>();
 
   // Get params from URL search params
@@ -35,6 +34,7 @@ function PretestPageContent() {
   const [metadata, setMetadata] = useState<Metadata | null>(null);
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string>();
+  const { setStatus } = useExamStore();
 
   useEffect(() => {
     async function fetchQuestions() {
@@ -123,6 +123,7 @@ function PretestPageContent() {
 
   function handleStartExam() {
     if (!examData) return;
+    setStatus("in-progress");
 
     router.push(
       `/exam/${id}?type=${type}&test_id=${metadata?.test_id}&attempt_id=${metadata?.attempt_id}`

app/exam/results/page.tsx

@@ -1,7 +1,7 @@
 "use client";
 
 import { useRouter } from "next/navigation";
-import React from "react";
+import React, { useEffect } from "react";
 import { ArrowLeft } from "lucide-react";
 import { useExamStore } from "@/stores/examStore";
 import QuestionItem from "@/components/QuestionItem";
@@ -10,7 +10,20 @@ import { getResultViews } from "@/lib/gallery-views";
 
 export default function ResultsPage() {
   const router = useRouter();
-  const { result, clearResult } = useExamStore();
+  const { result, clearResult, setStatus, status } = useExamStore();
+
+  useEffect(() => {
+    const handlePopState = () => {
+      if (status !== "finished") {
+        router.replace(`/categories`);
+      }
+    };
+
+    window.addEventListener("popstate", handlePopState);
+    return () => {
+      window.removeEventListener("popstate", handlePopState);
+    };
+  }, [status, router, setStatus]);
 
   if (!result) {
     return (
@@ -21,8 +34,9 @@ export default function ResultsPage() {
   }
 
   const handleBackToHome = () => {
-    clearResult();
+    setStatus("not-started"); // ✅ reset exam flow
-    router.push("/categories");
+    clearResult(); // ✅ clear stored results
+    router.replace("/categories"); // ✅ prevent re-entry
   };
 
   const views = getResultViews(result);

hooks/useExamExitGuard.ts

@@ -0,0 +1,42 @@
+import { useRouter, usePathname } from "next/navigation";
+import { useEffect } from "react";
+import { useExamStore } from "@/stores/examStore";
+import { useTimerStore } from "@/stores/timerStore";
+
+export function useExamExitGuard(type: string) {
+  const { status, setStatus, cancelExam } = useExamStore();
+  const router = useRouter();
+  const pathname = usePathname();
+  const { stopTimer } = useTimerStore();
+
+  // Guard page render: always redirect if status invalid
+  useEffect(() => {
+    if (status !== "in-progress") {
+      router.replace(`/categories/${type}s`);
+    }
+  }, [status, router, type]);
+
+  // Confirm before leaving page / tab close
+  useEffect(() => {
+    const handleBeforeUnload = (e: BeforeUnloadEvent) => {
+      if (status === "in-progress") {
+        e.preventDefault();
+        e.returnValue = ""; // shows native browser dialog
+      }
+    };
+    window.addEventListener("beforeunload", handleBeforeUnload);
+    return () => window.removeEventListener("beforeunload", handleBeforeUnload);
+  }, [status]);
+
+  // Call this to quit exam manually
+  const showExitDialog = () => {
+    if (window.confirm("Are you sure you want to quit the exam?")) {
+      setStatus("finished");
+      stopTimer();
+      cancelExam();
+      router.replace(`/categories/${type}s`);
+    }
+  };
+
+  return { showExitDialog };
+}

stores/examStore.ts

@@ -7,10 +7,14 @@ import { ExamResult } from "@/types/exam";
 
 // Result type (based on your API response)
 
+type ExamStatus = "not-started" | "in-progress" | "finished";
+
 interface ExamState {
   test: Test | null;
   answers: Answer[];
   result: ExamResult | null;
+  status: ExamStatus;
+  setStatus: (status: ExamStatus) => void;
 
   startExam: (testType: string, testId: string) => Promise<Test | null>;
   setAnswer: (questionIndex: number, answer: Answer) => void;
@@ -23,6 +27,8 @@ export const useExamStore = create<ExamState>((set, get) => ({
   test: null,
   answers: [],
   result: null,
+  status: "not-started",
+  setStatus: (status) => set({ status }),
 
   // start exam
   startExam: async (testType: string, testId: string) => {