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src/views/InstructorView.js

@@ -477,129 +477,170 @@ export function setupInstructorEvents() {
 
     // Create Room
     if (createBtn) {
-        createBtn.addEventListener('click', async () => {
-            const roomCode = Math.random().toString(36).substring(2, 8).toUpperCase();
-            try {
-                // Ensure roomInfo is visible
-                const roomInfo = document.getElementById('room-info');
-                const displayRoomCode = document.getElementById('display-room-code');
-                const createContainer = document.getElementById('create-room-container');
-                const dashboardContent = document.getElementById('dashboard-content');
-
-                await createRoom(roomCode, currentInstructor ? currentInstructor.name : 'Unknown');
-                displayRoomCode.textContent = roomCode;
-
-                // Store in LocalStorage
-                localStorage.setItem('vibecoding_room_code', roomCode);
-                localStorage.setItem('vibecoding_is_host', 'true');
-
-                // UI Updates
-                createContainer.classList.add('hidden');
-                roomInfo.classList.remove('hidden');
-                dashboardContent.classList.remove('hidden');
-
-                // Start Subscription
-                subscribeToRoom(roomCode, (data) => {
-                    updateDashboard(data);
-                });
+        // Dashboard Update Logic
+        const updateDashboard = (data) => {
+            const dashboardContent = document.getElementById('dashboard-content');
+            const heatmapBody = document.getElementById('heatmap-body');
+            const heatmapHeader = document.getElementById('heatmap-header');
 
-            } catch (e) {
-                console.error(e);
-                alert("無法建立教室: " + e.message);
+            if (!data || !data.users) {
+                heatmapBody.innerHTML = '<tr><td colspan="100" class="text-center py-10 text-gray-500">尚無學員加入</td></tr>';
+                return;
             }
-        });
-    }
 
-    // Rejoin Room
-    const rejoinBtn = document.getElementById('rejoin-room-btn');
-    if (rejoinBtn) {
-        rejoinBtn.addEventListener('click', async () => {
-            const inputCode = document.getElementById('rejoin-room-code').value.trim().toUpperCase();
-            if (!inputCode) return alert("請輸入代碼");
+            // Just a simple render for now - can be expanded
+            // Clearing existing rows
+            heatmapBody.innerHTML = '';
 
-            try {
-                // Ensure roomInfo is visible
-                const roomInfo = document.getElementById('room-info');
-                const displayRoomCode = document.getElementById('display-room-code');
-                const createContainer = document.getElementById('create-room-container');
-                const dashboardContent = document.getElementById('dashboard-content');
-
-                // Check if room exists first (optional, subscribe handles it usually)
-                displayRoomCode.textContent = inputCode;
-                localStorage.setItem('vibecoding_room_code', inputCode);
-
-                // UI Updates
-                createContainer.classList.add('hidden');
-                roomInfo.classList.remove('hidden');
-                dashboardContent.classList.remove('hidden');
-
-                subscribeToRoom(inputCode, (data) => {
-                    updateDashboard(data);
-                });
-            } catch (e) {
-                alert("重回失敗: " + e.message);
-            }
-        });
+            // This part needs real logic based on your data structure
+            // For now, let's just list users to prove it works
+            Object.values(data.users).forEach(user => {
+                const tr = document.createElement('tr');
+                tr.innerHTML = `<td class="p-3 text-white">${user.nickname || 'Unknown'}</td>`;
+                heatmapBody.appendChild(tr);
+            });
+        }
+
+        // Create Room
+        if (createBtn) {
+            createBtn.addEventListener('click', async () => {
+                // 4-Digit Room Code
+                const roomCode = Math.floor(1000 + Math.random() * 9000).toString();
+                try {
+                    // Ensure roomInfo is visible
+                    const roomInfo = document.getElementById('room-info');
+                    const displayRoomCode = document.getElementById('display-room-code');
+                    const createContainer = document.getElementById('create-room-container');
+                    const dashboardContent = document.getElementById('dashboard-content');
+
+                    await createRoom(roomCode, currentInstructor ? currentInstructor.name : 'Unknown');
+                    displayRoomCode.textContent = roomCode;
+
+                    // Store in LocalStorage
+                    localStorage.setItem('vibecoding_room_code', roomCode);
+                    localStorage.setItem('vibecoding_is_host', 'true');
+
+                    // UI Updates
+                    createContainer.classList.add('hidden');
+                    roomInfo.classList.remove('hidden');
+                    dashboardContent.classList.remove('hidden');
+
+                    // Start Subscription
+                    subscribeToRoom(roomCode, (data) => {
+                        updateDashboard(data);
+                    });
+
+                } catch (e) {
+                    console.error(e);
+                    alert("無法建立教室: " + e.message);
+                }
+            });
+        }
+
+    } catch (e) {
+        console.error(e);
+        alert("無法建立教室: " + e.message);
     }
+});
+    }
+
+// Rejoin Room
+const rejoinBtn = document.getElementById('rejoin-room-btn');
+if (rejoinBtn) {
+    rejoinBtn.addEventListener('click', async () => {
+        const inputCode = document.getElementById('rejoin-room-code').value.trim().toUpperCase();
+        if (!inputCode) return alert("請輸入代碼");
 
-    // Leave Room
-    const leaveBtn = document.getElementById('leave-room-btn');
-    if (leaveBtn) {
-        leaveBtn.addEventListener('click', () => {
+        try {
+            // Ensure roomInfo is visible
             const roomInfo = document.getElementById('room-info');
+            const displayRoomCode = document.getElementById('display-room-code');
             const createContainer = document.getElementById('create-room-container');
             const dashboardContent = document.getElementById('dashboard-content');
-            const displayRoomCode = document.getElementById('display-room-code');
 
-            localStorage.removeItem('vibecoding_room_code');
-            localStorage.removeItem('vibecoding_is_host');
+            // Check if room exists first (optional, subscribe handles it usually)
+            displayRoomCode.textContent = inputCode;
+            localStorage.setItem('vibecoding_room_code', inputCode);
 
-            displayRoomCode.textContent = '';
-            roomInfo.classList.add('hidden');
-            dashboardContent.classList.add('hidden');
-            createContainer.classList.remove('hidden');
+            // UI Updates
+            createContainer.classList.add('hidden');
+            roomInfo.classList.remove('hidden');
+            dashboardContent.classList.remove('hidden');
 
-            // Unsubscribe logic if needed, usually auto-handled by new subscription or page reload
-            window.location.reload();
-        });
-    }
+            subscribeToRoom(inputCode, (data) => {
+                // Check if updateDashboard is defined in scope
+                if (typeof updateDashboard === 'function') {
+                    updateDashboard(data);
+                } else {
+                    console.error("updateDashboard function missing");
+                }
+            });
+        } catch (e) {
+            alert("重回失敗: " + e.message);
+        }
+    });
+}
 
-    // Nav to Admin
-    if (navAdminBtn) {
-        navAdminBtn.addEventListener('click', () => {
-            window.location.hash = '#admin';
-        });
-    }
+// Leave Room
+const leaveBtn = document.getElementById('leave-room-btn');
+if (leaveBtn) {
+    leaveBtn.addEventListener('click', () => {
+        const roomInfo = document.getElementById('room-info');
+        const createContainer = document.getElementById('create-room-container');
+        const dashboardContent = document.getElementById('dashboard-content');
+        const displayRoomCode = document.getElementById('display-room-code');
+
+        localStorage.removeItem('vibecoding_room_code');
+        localStorage.removeItem('vibecoding_is_host');
+
+        displayRoomCode.textContent = '';
+        roomInfo.classList.add('hidden');
+        dashboardContent.classList.add('hidden');
+        createContainer.classList.remove('hidden');
+
+        // Unsubscribe logic if needed, usually auto-handled by new subscription or page reload
+        window.location.reload();
+    });
+}
+
+// Nav to Admin
+if (navAdminBtn) {
+    navAdminBtn.addEventListener('click', () => {
+        window.location.hash = '#admin';
+    });
+}
 
-    // Handle Instructor Management
-    navInstBtn.addEventListener('click', async () => {
-        const modal = document.getElementById('instructor-modal');
-        const listBody = document.getElementById('instructor-list-body');
+// Handle Instructor Management
+navInstBtn.addEventListener('click', async () => {
+    const modal = document.getElementById('instructor-modal');
+    const listBody = document.getElementById('instructor-list-body');
 
-        // Load list
-        const instructors = await getInstructors();
-        listBody.innerHTML = instructors.map(inst => `
+    // Load list
+    const instructors = await getInstructors();
+    listBody.innerHTML = instructors.map(inst => `
             <tr class="border-b border-gray-700 hover:bg-gray-800">
                 <td class="p-3">${inst.name}</td>
                 <td class="p-3 font-mono text-sm text-cyan-400">${inst.email}</td>
                 <td class="p-3 text-xs">
                     ${inst.permissions?.map(p => {
-            const map = { create_room: '開房', add_question: '題目', manage_instructors: '管理' };
-            return `<span class="bg-gray-700 px-2 py-1 rounded mr-1">${map[p] || p}</span>`;
-        }).join('')}
+        const map = { create_room: '開房', add_question: '題目', manage_instructors: '管理' };
+        return `<span class="bg-gray-700 px-2 py-1 rounded mr-1">${map[p] || p}</span>`;
+    }).join('')}
                 </td>
                 <td class="p-3">
                     ${inst.role === 'admin' ? '<span class="text-gray-500 italic">不可移除</span>' :
-                `<button class="text-red-400 hover:text-red-300" onclick="window.removeInst('${inst.email}')">移除</button>`}
+            `<button class="text-red-400 hover:text-red-300" onclick="window.removeInst('${inst.email}')">移除</button>`}
                 </td>
             </tr>
             `).join('');
 
-        modal.classList.remove('hidden');
-    });
+    modal.classList.remove('hidden');
+});
 
-    // Add New Instructor
-    document.getElementById('btn-add-inst').addEventListener('click', async () => {
+// Add New Instructor
+const addInstBtn = document.getElementById('btn-add-inst');
+if (addInstBtn) {
+    addInstBtn.addEventListener('click', async () => {
         const email = document.getElementById('new-inst-email').value.trim();
         const name = document.getElementById('new-inst-name').value.trim();
 
@@ -620,217 +661,219 @@ export function setupInstructorEvents() {
             alert("新增失敗: " + e.message);
         }
     });
+}
+});
 
-    // Global helper for remove (hacky but works for simple onclick)
-    window.removeInst = async (email) => {
-        if (confirm(`確定移除 ${email}?`)) {
-            try {
-                await removeInstructor(email);
-                navInstBtn.click(); // Reload
-            } catch (e) {
-                alert(e.message);
-            }
+// Global helper for remove (hacky but works for simple onclick)
+window.removeInst = async (email) => {
+    if (confirm(`確定移除 ${email}?`)) {
+        try {
+            await removeInstructor(email);
+            navInstBtn.click(); // Reload
+        } catch (e) {
+            alert(e.message);
         }
-    };
+    }
+};
 
-    // Auto Check Auth (Persistence)
-    // We rely on Firebase Auth state observer instead of session storage for security?
-    // Or we can just check if user is already signed in.
-    import("../services/firebase.js").then(async ({ auth }) => {
-        // Handle Redirect Result first
-        try {
-            console.log("Initializing Auth Check...");
-            const { handleRedirectResult } = await import("../services/auth.js");
-            const redirectUser = await handleRedirectResult();
-            if (redirectUser) console.log("Redirect User Found:", redirectUser.email);
-        } catch (e) { console.warn("Redirect check failed", e); }
-
-        auth.onAuthStateChanged(async (user) => {
-            console.log("Auth State Changed to:", user ? user.email : "Logged Out");
-            if (user) {
-                try {
-                    console.log("Checking permissions for:", user.email);
-                    const instructorData = await checkInstructorPermission(user);
-                    console.log("Permission Result:", instructorData);
-
-                    if (instructorData) {
-                        console.log("Hiding Modal and Setting Permissions...");
-                        authModal.classList.add('hidden');
-                        checkPermissions(instructorData);
-                    } else {
-                        console.warn("User logged in but not an instructor.");
-                        // Show unauthorized message
-                        authErrorMsg.textContent = "此帳號無講師權限";
-                        authErrorMsg.classList.remove('hidden');
-                        authModal.classList.remove('hidden'); // Ensure modal stays up
-                    }
-                } catch (e) {
-                    console.error("Permission Check Failed:", e);
-                    authErrorMsg.textContent = "權限檢查失敗: " + e.message;
+// Auto Check Auth (Persistence)
+// We rely on Firebase Auth state observer instead of session storage for security?
+// Or we can just check if user is already signed in.
+import("../services/firebase.js").then(async ({ auth }) => {
+    // Handle Redirect Result first
+    try {
+        console.log("Initializing Auth Check...");
+        const { handleRedirectResult } = await import("../services/auth.js");
+        const redirectUser = await handleRedirectResult();
+        if (redirectUser) console.log("Redirect User Found:", redirectUser.email);
+    } catch (e) { console.warn("Redirect check failed", e); }
+
+    auth.onAuthStateChanged(async (user) => {
+        console.log("Auth State Changed to:", user ? user.email : "Logged Out");
+        if (user) {
+            try {
+                console.log("Checking permissions for:", user.email);
+                const instructorData = await checkInstructorPermission(user);
+                console.log("Permission Result:", instructorData);
+
+                if (instructorData) {
+                    console.log("Hiding Modal and Setting Permissions...");
+                    authModal.classList.add('hidden');
+                    checkPermissions(instructorData);
+                } else {
+                    console.warn("User logged in but not an instructor.");
+                    // Show unauthorized message
+                    authErrorMsg.textContent = "此帳號無講師權限";
                     authErrorMsg.classList.remove('hidden');
+                    authModal.classList.remove('hidden'); // Ensure modal stays up
                 }
-            } else {
-                authModal.classList.remove('hidden');
+            } catch (e) {
+                console.error("Permission Check Failed:", e);
+                authErrorMsg.textContent = "權限檢查失敗: " + e.message;
+                authErrorMsg.classList.remove('hidden');
             }
-        });
+        } else {
+            authModal.classList.remove('hidden');
+        }
     });
+});
 
-    // Define Kick Function globally (robust against auth flow)
-    window.confirmKick = async (userId, nickname) => {
-        if (confirm(`確定要踢出 ${nickname} 嗎？此動作無法復原。`)) {
-            try {
-                const { removeUser } = await import("../services/classroom.js");
-                await removeUser(userId);
-                // UI will update automatically via subscribeToRoom
-            } catch (e) {
-                console.error("Kick failed:", e);
-                alert("移除失敗");
-            }
+// Define Kick Function globally (robust against auth flow)
+window.confirmKick = async (userId, nickname) => {
+    if (confirm(`確定要踢出 ${nickname} 嗎？此動作無法復原。`)) {
+        try {
+            const { removeUser } = await import("../services/classroom.js");
+            await removeUser(userId);
+            // UI will update automatically via subscribeToRoom
+        } catch (e) {
+            console.error("Kick failed:", e);
+            alert("移除失敗");
         }
-    };
+    }
+};
 
 
-    // Snapshot Logic
-    snapshotBtn.addEventListener('click', async () => {
-        if (isSnapshotting || typeof htmlToImage === 'undefined') {
-            if (typeof htmlToImage === 'undefined') alert("截圖元件尚未載入，請稍候再試");
-            return;
-        }
-        isSnapshotting = true;
-
-        const overlay = document.getElementById('snapshot-overlay');
-        const countEl = document.getElementById('countdown-number');
-        const container = document.getElementById('group-photo-container');
-        const modal = document.getElementById('group-photo-modal');
-
-        // Close button hide
-        const closeBtn = modal.querySelector('button');
-        if (closeBtn) closeBtn.style.opacity = '0';
-        snapshotBtn.style.opacity = '0';
-
-        overlay.classList.remove('hidden');
-        overlay.classList.add('flex');
-
-        // Countdown Sequence
-        const runCountdown = (num) => new Promise(resolve => {
-            countEl.textContent = num;
-            countEl.style.transform = 'scale(1.5)';
-            countEl.style.opacity = '1';
-
-            // Animation reset
-            requestAnimationFrame(() => {
-                countEl.style.transition = 'all 0.5s ease-out';
-                countEl.style.transform = 'scale(1)';
-                countEl.style.opacity = '0.5';
-                setTimeout(resolve, 1000);
-            });
+// Snapshot Logic
+snapshotBtn.addEventListener('click', async () => {
+    if (isSnapshotting || typeof htmlToImage === 'undefined') {
+        if (typeof htmlToImage === 'undefined') alert("截圖元件尚未載入，請稍候再試");
+        return;
+    }
+    isSnapshotting = true;
+
+    const overlay = document.getElementById('snapshot-overlay');
+    const countEl = document.getElementById('countdown-number');
+    const container = document.getElementById('group-photo-container');
+    const modal = document.getElementById('group-photo-modal');
+
+    // Close button hide
+    const closeBtn = modal.querySelector('button');
+    if (closeBtn) closeBtn.style.opacity = '0';
+    snapshotBtn.style.opacity = '0';
+
+    overlay.classList.remove('hidden');
+    overlay.classList.add('flex');
+
+    // Countdown Sequence
+    const runCountdown = (num) => new Promise(resolve => {
+        countEl.textContent = num;
+        countEl.style.transform = 'scale(1.5)';
+        countEl.style.opacity = '1';
+
+        // Animation reset
+        requestAnimationFrame(() => {
+            countEl.style.transition = 'all 0.5s ease-out';
+            countEl.style.transform = 'scale(1)';
+            countEl.style.opacity = '0.5';
+            setTimeout(resolve, 1000);
         });
+    });
 
-        await runCountdown(3);
-        await runCountdown(2);
-        await runCountdown(1);
-
-        // Action!
-        countEl.textContent = '';
-        overlay.classList.add('hidden');
-
-        // 1. Emojis Explosion
-        const emojis = ['🤘', '✌️', '👍', '🫶', '😎', '🔥'];
-        const cards = container.querySelectorAll('.group\\/card');
-
-        cards.forEach(card => {
-            // Find the monster image container
-            const imgContainer = card.querySelector('.monster-img-container');
-            if (!imgContainer) return;
-
-            // Random Emoji
-            const emoji = emojis[Math.floor(Math.random() * emojis.length)];
-            const emojiEl = document.createElement('div');
-            emojiEl.textContent = emoji;
-            // Position: Top-Right of the *Image*, slightly overlapping
-            emojiEl.className = 'absolute -top-2 -right-2 text-2xl animate-bounce z-50 drop-shadow-md transform rotate-12';
-            emojiEl.style.animationDuration = '0.6s';
-            imgContainer.appendChild(emojiEl);
-
-            // Remove after 3s
-            setTimeout(() => emojiEl.remove(), 3000);
-        });
+    await runCountdown(3);
+    await runCountdown(2);
+    await runCountdown(1);
+
+    // Action!
+    countEl.textContent = '';
+    overlay.classList.add('hidden');
+
+    // 1. Emojis Explosion
+    const emojis = ['🤘', '✌️', '👍', '🫶', '😎', '🔥'];
+    const cards = container.querySelectorAll('.group\\/card');
+
+    cards.forEach(card => {
+        // Find the monster image container
+        const imgContainer = card.querySelector('.monster-img-container');
+        if (!imgContainer) return;
+
+        // Random Emoji
+        const emoji = emojis[Math.floor(Math.random() * emojis.length)];
+        const emojiEl = document.createElement('div');
+        emojiEl.textContent = emoji;
+        // Position: Top-Right of the *Image*, slightly overlapping
+        emojiEl.className = 'absolute -top-2 -right-2 text-2xl animate-bounce z-50 drop-shadow-md transform rotate-12';
+        emojiEl.style.animationDuration = '0.6s';
+        imgContainer.appendChild(emojiEl);
+
+        // Remove after 3s
+        setTimeout(() => emojiEl.remove(), 3000);
+    });
 
-        // 2. Capture using html-to-image
-        setTimeout(async () => {
-            try {
-                // Flash Effect
-                const flash = document.createElement('div');
-                flash.className = 'fixed inset-0 bg-white z-[100] transition-opacity duration-300 pointer-events-none';
-                document.body.appendChild(flash);
-                setTimeout(() => flash.style.opacity = '0', 50);
-                setTimeout(() => flash.remove(), 300);
-
-                // Use htmlToImage.toPng
-                const dataUrl = await htmlToImage.toPng(container, {
-                    backgroundColor: '#111827',
-                    pixelRatio: 2,
-                    cacheBust: true,
-                });
+    // 2. Capture using html-to-image
+    setTimeout(async () => {
+        try {
+            // Flash Effect
+            const flash = document.createElement('div');
+            flash.className = 'fixed inset-0 bg-white z-[100] transition-opacity duration-300 pointer-events-none';
+            document.body.appendChild(flash);
+            setTimeout(() => flash.style.opacity = '0', 50);
+            setTimeout(() => flash.remove(), 300);
+
+            // Use htmlToImage.toPng
+            const dataUrl = await htmlToImage.toPng(container, {
+                backgroundColor: '#111827',
+                pixelRatio: 2,
+                cacheBust: true,
+            });
 
-                // Download
-                const link = document.createElement('a');
-                const dateStr = new Date().toISOString().slice(0, 10);
-                link.download = `VIBE_Class_Photo_${dateStr}.png`;
-                link.href = dataUrl;
-                link.click();
+            // Download
+            const link = document.createElement('a');
+            const dateStr = new Date().toISOString().slice(0, 10);
+            link.download = `VIBE_Class_Photo_${dateStr}.png`;
+            link.href = dataUrl;
+            link.click();
 
-            } catch (e) {
-                console.error("Snapshot failed:", e);
-                alert("截圖失敗 (請嘗試手動截圖/PrtSc)\n原因: " + e.message);
-            } finally {
-                // Restore UI
-                if (closeBtn) closeBtn.style.opacity = '1';
-                snapshotBtn.style.opacity = '1';
-                isSnapshotting = false;
-            }
-        }, 600); // Slight delay for emojis to appear
-    });
+        } catch (e) {
+            console.error("Snapshot failed:", e);
+            alert("截圖失敗 (請嘗試手動截圖/PrtSc)\n原因: " + e.message);
+        } finally {
+            // Restore UI
+            if (closeBtn) closeBtn.style.opacity = '1';
+            snapshotBtn.style.opacity = '1';
+            isSnapshotting = false;
+        }
+    }, 600); // Slight delay for emojis to appear
+});
 
-    // Group Photo Logic
-    groupPhotoBtn.addEventListener('click', () => {
-        const modal = document.getElementById('group-photo-modal');
-        const container = document.getElementById('group-photo-container');
-        const dateEl = document.getElementById('photo-date');
+// Group Photo Logic
+groupPhotoBtn.addEventListener('click', () => {
+    const modal = document.getElementById('group-photo-modal');
+    const container = document.getElementById('group-photo-container');
+    const dateEl = document.getElementById('photo-date');
 
-        // Update Date
-        const now = new Date();
-        dateEl.textContent = `${now.getFullYear()}.${String(now.getMonth() + 1).padStart(2, '0')}.${String(now.getDate()).padStart(2, '0')} `;
+    // Update Date
+    const now = new Date();
+    dateEl.textContent = `${now.getFullYear()}.${String(now.getMonth() + 1).padStart(2, '0')}.${String(now.getDate()).padStart(2, '0')} `;
 
-        // Get saved name
-        const savedName = localStorage.getItem('vibecoding_instructor_name') || '講師 (Instructor)';
+    // Get saved name
+    const savedName = localStorage.getItem('vibecoding_instructor_name') || '講師 (Instructor)';
 
-        container.innerHTML = '';
+    container.innerHTML = '';
 
-        // 1. Container for Relative Positioning with Custom Background
-        const relativeContainer = document.createElement('div');
-        relativeContainer.className = 'relative w-full h-[600px] md:h-[700px] overflow-hidden rounded-3xl border border-gray-700/30 shadow-2xl flex items-center justify-center bg-cover bg-center';
-        relativeContainer.style.backgroundImage = "url('assets/photobg.png')";
-        container.appendChild(relativeContainer);
+    // 1. Container for Relative Positioning with Custom Background
+    const relativeContainer = document.createElement('div');
+    relativeContainer.className = 'relative w-full h-[600px] md:h-[700px] overflow-hidden rounded-3xl border border-gray-700/30 shadow-2xl flex items-center justify-center bg-cover bg-center';
+    relativeContainer.style.backgroundImage = "url('assets/photobg.png')";
+    container.appendChild(relativeContainer);
 
-        // Watermark (Bottom Right, High Z-Index, Gradient Text, Dark Backdrop)
-        const watermark = document.createElement('div');
-        watermark.className = 'absolute bottom-2 right-2 md:bottom-4 md:right-4 z-[60] bg-black/70 backdrop-blur-sm rounded-lg px-4 py-2 pointer-events-none select-none border border-white/10 shadow-lg';
+    // Watermark (Bottom Right, High Z-Index, Gradient Text, Dark Backdrop)
+    const watermark = document.createElement('div');
+    watermark.className = 'absolute bottom-2 right-2 md:bottom-4 md:right-4 z-[60] bg-black/70 backdrop-blur-sm rounded-lg px-4 py-2 pointer-events-none select-none border border-white/10 shadow-lg';
 
-        const d = new Date();
-        const dateStr = `${d.getFullYear()}.${String(d.getMonth() + 1).padStart(2, '0')}.${String(d.getDate()).padStart(2, '0')} `;
+    const d = new Date();
+    const dateStr = `${d.getFullYear()}.${String(d.getMonth() + 1).padStart(2, '0')}.${String(d.getDate()).padStart(2, '0')} `;
 
-        watermark.innerHTML = `
+    watermark.innerHTML = `
             <span class="text-lg md:text-2xl font-black font-mono bg-clip-text text-transparent bg-gradient-to-r from-cyan-400 to-purple-400 tracking-wider">
                 ${dateStr} VibeCoding 怪獸成長營
             </span>
             `;
-        relativeContainer.appendChild(watermark);
+    relativeContainer.appendChild(watermark);
 
-        // 2. Instructor Section (Absolute Center)
-        const instructorSection = document.createElement('div');
-        instructorSection.className = 'absolute top-1/2 left-1/2 transform -translate-x-1/2 -translate-y-1/2 flex flex-col items-center justify-center z-20 group cursor-pointer';
-        instructorSection.innerHTML = `
+    // 2. Instructor Section (Absolute Center)
+    const instructorSection = document.createElement('div');
+    instructorSection.className = 'absolute top-1/2 left-1/2 transform -translate-x-1/2 -translate-y-1/2 flex flex-col items-center justify-center z-20 group cursor-pointer';
+    instructorSection.innerHTML = `
             <div class="relative">
                 <div class="absolute inset-0 bg-yellow-500/20 blur-3xl rounded-full animate-pulse"></div>
                 <!--Pixel Art Avatar-->
@@ -849,98 +892,98 @@ export function setupInstructorEvents() {
                     </div>
             </div>
             `;
-        relativeContainer.appendChild(instructorSection);
-
-        // Save name on change
-        setTimeout(() => {
-            const input = document.getElementById('instructor-name-input');
-            if (input) {
-                input.addEventListener('input', (e) => {
-                    localStorage.setItem('vibecoding_instructor_name', e.target.value);
-                });
-            }
-        }, 100);
-
-        // 3. Students Scatter
-        if (currentStudents.length > 0) {
-            // Randomize array to prevent fixed order bias
-            const students = [...currentStudents].sort(() => Math.random() - 0.5);
-            const total = students.length;
-
-            // --- Dynamic Sizing Logic ---
-            let sizeClass = 'w-20 h-20 md:w-24 md:h-24'; // Default (Size 100%)
-            let scaleFactor = 1.0;
-
-            if (total >= 40) {
-                sizeClass = 'w-12 h-12 md:w-14 md:h-14'; // Size 60%
-                scaleFactor = 0.6;
-            } else if (total >= 20) {
-                sizeClass = 'w-16 h-16 md:w-20 md:h-20'; // Size 80%
-                scaleFactor = 0.8;
-            }
+    relativeContainer.appendChild(instructorSection);
 
-            students.forEach((s, index) => {
-                const progressMap = s.progress || {};
-                const totalLikes = Object.values(progressMap).reduce((acc, p) => acc + (p.likes || 0), 0);
-                const totalCompleted = Object.values(progressMap).filter(p => p.status === 'completed').length;
-
-                // FIXED: Prioritize stored ID if valid (same as StudentView logic)
-                let monster;
-                if (s.monster_id && s.monster_id !== 'Egg' && s.monster_id !== 'Unknown') {
-                    const stored = MONSTER_DEFS?.find(m => m.id === s.monster_id);
-                    if (stored) {
-                        monster = stored;
-                    } else {
-                        // Fallback if ID invalid
-                        monster = getNextMonster(s.monster_stage || 0, totalLikes, total, s.monster_id);
-                    }
+    // Save name on change
+    setTimeout(() => {
+        const input = document.getElementById('instructor-name-input');
+        if (input) {
+            input.addEventListener('input', (e) => {
+                localStorage.setItem('vibecoding_instructor_name', e.target.value);
+            });
+        }
+    }, 100);
+
+    // 3. Students Scatter
+    if (currentStudents.length > 0) {
+        // Randomize array to prevent fixed order bias
+        const students = [...currentStudents].sort(() => Math.random() - 0.5);
+        const total = students.length;
+
+        // --- Dynamic Sizing Logic ---
+        let sizeClass = 'w-20 h-20 md:w-24 md:h-24'; // Default (Size 100%)
+        let scaleFactor = 1.0;
+
+        if (total >= 40) {
+            sizeClass = 'w-12 h-12 md:w-14 md:h-14'; // Size 60%
+            scaleFactor = 0.6;
+        } else if (total >= 20) {
+            sizeClass = 'w-16 h-16 md:w-20 md:h-20'; // Size 80%
+            scaleFactor = 0.8;
+        }
+
+        students.forEach((s, index) => {
+            const progressMap = s.progress || {};
+            const totalLikes = Object.values(progressMap).reduce((acc, p) => acc + (p.likes || 0), 0);
+            const totalCompleted = Object.values(progressMap).filter(p => p.status === 'completed').length;
+
+            // FIXED: Prioritize stored ID if valid (same as StudentView logic)
+            let monster;
+            if (s.monster_id && s.monster_id !== 'Egg' && s.monster_id !== 'Unknown') {
+                const stored = MONSTER_DEFS?.find(m => m.id === s.monster_id);
+                if (stored) {
+                    monster = stored;
                 } else {
+                    // Fallback if ID invalid
                     monster = getNextMonster(s.monster_stage || 0, totalLikes, total, s.monster_id);
                 }
+            } else {
+                monster = getNextMonster(s.monster_stage || 0, totalLikes, total, s.monster_id);
+            }
 
-                // --- FIXED: Even Arc Distribution (Safe Zone: 135 deg to 405 deg) ---
-                // Avoids Bottom Right (0-90) and Bottom Center (90-120) entirely
-                const minR = 220;
-                // Avoids Bottom Right (0-90) and Bottom Center (90-120) entirely
+            // --- FIXED: Even Arc Distribution (Safe Zone: 135 deg to 405 deg) ---
+            // Avoids Bottom Right (0-90) and Bottom Center (90-120) entirely
+            const minR = 220;
+            // Avoids Bottom Right (0-90) and Bottom Center (90-120) entirely
 
-                // Safe Arc Range: Starts at 135 deg (Bottom Left) -> Goes CW -> Ends at 405 deg (45 deg, Bottom Right)
-                // Total Span = 270 degrees
-                // If many students, use double ring
+            // Safe Arc Range: Starts at 135 deg (Bottom Left) -> Goes CW -> Ends at 405 deg (45 deg, Bottom Right)
+            // Total Span = 270 degrees
+            // If many students, use double ring
 
-                const safeStartAngle = 135 * (Math.PI / 180);
-                const safeSpan = 270 * (Math.PI / 180);
+            const safeStartAngle = 135 * (Math.PI / 180);
+            const safeSpan = 270 * (Math.PI / 180);
 
-                // Distribute evenly
-                // If only 1 student, put at top (270 deg / 4.71 rad)
-                let finalAngle;
+            // Distribute evenly
+            // If only 1 student, put at top (270 deg / 4.71 rad)
+            let finalAngle;
 
-                if (total === 1) {
-                    finalAngle = 270 * (Math.PI / 180);
-                } else {
-                    const step = safeSpan / (total - 1);
-                    finalAngle = safeStartAngle + (step * index);
-                }
+            if (total === 1) {
+                finalAngle = 270 * (Math.PI / 180);
+            } else {
+                const step = safeSpan / (total - 1);
+                finalAngle = safeStartAngle + (step * index);
+            }
 
-                // Radius: Fixed base + slight variation for "natural" look (but not overlap causing)
-                // Double ring logic if crowded
-                let radius = minR + (index % 2) * 40; // Zigzag radius (220, 260, 220...) to minimize overlap
+            // Radius: Fixed base + slight variation for "natural" look (but not overlap causing)
+            // Double ring logic if crowded
+            let radius = minR + (index % 2) * 40; // Zigzag radius (220, 260, 220...) to minimize overlap
 
-                // Reduce zigzag if few students
-                if (total < 10) radius = minR + (index % 2) * 20;
+            // Reduce zigzag if few students
+            if (total < 10) radius = minR + (index % 2) * 20;
 
-                const xOff = Math.cos(finalAngle) * radius;
-                const yOff = Math.sin(finalAngle) * radius * 0.8;
+            const xOff = Math.cos(finalAngle) * radius;
+            const yOff = Math.sin(finalAngle) * radius * 0.8;
 
-                const card = document.createElement('div');
-                card.className = 'absolute flex flex-col items-center group/card z-10 hover:z-50 transition-all duration-500 cursor-move';
+            const card = document.createElement('div');
+            card.className = 'absolute flex flex-col items-center group/card z-10 hover:z-50 transition-all duration-500 cursor-move';
 
-                card.style.left = `calc(50% + ${xOff}px)`;
-                card.style.top = `calc(50% + ${yOff}px)`;
-                card.style.transform = 'translate(-50%, -50%)';
+            card.style.left = `calc(50% + ${xOff}px)`;
+            card.style.top = `calc(50% + ${yOff}px)`;
+            card.style.transform = 'translate(-50%, -50%)';
 
-                const floatDelay = Math.random() * 2;
+            const floatDelay = Math.random() * 2;
 
-                card.innerHTML = `
+            card.innerHTML = `
             <!--Top Info: Monster Stats-->
             <div class="mb-1 text-center bg-gray-900/60 backdrop-blur-sm rounded-lg px-2 py-1 border border-gray-600/30 group-hover/card:bg-gray-800 group-hover/card:border-cyan-500/50 transition-all opacity-80 group-hover/card:opacity-100 transform translate-y-2 group-hover/card:translate-y-0 duration-300">
                 <div class="text-[10px] text-gray-300 mb-0.5 whitespace-nowrap">${monster.name.split(' ')[1] || monster.name}</div>
@@ -965,77 +1008,77 @@ export function setupInstructorEvents() {
                 <div class="text-xs font-bold text-white shadow-black drop-shadow-md whitespace-nowrap tracking-wide">${s.nickname}</div>
             </div>
             `;
-                relativeContainer.appendChild(card);
+            relativeContainer.appendChild(card);
 
-                // Enable Drag & Drop
-                setupDraggable(card, relativeContainer);
-            });
-        }
+            // Enable Drag & Drop
+            setupDraggable(card, relativeContainer);
+        });
+    }
 
-        modal.classList.remove('hidden');
+    modal.classList.remove('hidden');
+});
+
+// Helper: Drag & Drop Logic
+function setupDraggable(el, container) {
+    let isDragging = false;
+    let startX, startY, initialLeft, initialTop;
+
+    el.addEventListener('mousedown', (e) => {
+        isDragging = true;
+        startX = e.clientX;
+        startY = e.clientY;
+
+        // Disable transition during drag for responsiveness
+        el.style.transition = 'none';
+        el.style.zIndex = 100; // Bring to front
+
+        // Convert current computed position to fixed pixels if relying on calc
+        const rect = el.getBoundingClientRect();
+        const containerRect = container.getBoundingClientRect();
+
+        // Calculate position relative to container
+        // The current transform is translate(-50%, -50%). 
+        // We want to set left/top such that the center remains under the mouse offset, 
+        // but for simplicity, let's just use current offsetLeft/Top if possible, 
+        // OR robustly recalculate from rects.
+
+        // Current center point relative to container:
+        const centerX = rect.left - containerRect.left + rect.width / 2;
+        const centerY = rect.top - containerRect.top + rect.height / 2;
+
+        // Set explicit pixel values replacing calc()
+        el.style.left = `${centerX}px`;
+        el.style.top = `${centerY}px`;
+
+        initialLeft = centerX;
+        initialTop = centerY;
     });
 
-    // Helper: Drag & Drop Logic
-    function setupDraggable(el, container) {
-        let isDragging = false;
-        let startX, startY, initialLeft, initialTop;
+    window.addEventListener('mousemove', (e) => {
+        if (!isDragging) return;
+        e.preventDefault();
 
-        el.addEventListener('mousedown', (e) => {
-            isDragging = true;
-            startX = e.clientX;
-            startY = e.clientY;
+        const dx = e.clientX - startX;
+        const dy = e.clientY - startY;
 
-            // Disable transition during drag for responsiveness
-            el.style.transition = 'none';
-            el.style.zIndex = 100; // Bring to front
-
-            // Convert current computed position to fixed pixels if relying on calc
-            const rect = el.getBoundingClientRect();
-            const containerRect = container.getBoundingClientRect();
-
-            // Calculate position relative to container
-            // The current transform is translate(-50%, -50%). 
-            // We want to set left/top such that the center remains under the mouse offset, 
-            // but for simplicity, let's just use current offsetLeft/Top if possible, 
-            // OR robustly recalculate from rects.
-
-            // Current center point relative to container:
-            const centerX = rect.left - containerRect.left + rect.width / 2;
-            const centerY = rect.top - containerRect.top + rect.height / 2;
-
-            // Set explicit pixel values replacing calc()
-            el.style.left = `${centerX}px`;
-            el.style.top = `${centerY}px`;
-
-            initialLeft = centerX;
-            initialTop = centerY;
-        });
-
-        window.addEventListener('mousemove', (e) => {
-            if (!isDragging) return;
-            e.preventDefault();
-
-            const dx = e.clientX - startX;
-            const dy = e.clientY - startY;
-
-            el.style.left = `${initialLeft + dx}px`;
-            el.style.top = `${initialTop + dy}px`;
-        });
+        el.style.left = `${initialLeft + dx}px`;
+        el.style.top = `${initialTop + dy}px`;
+    });
 
-        window.addEventListener('mouseup', () => {
-            if (isDragging) {
-                isDragging = false;
-                el.style.transition = ''; // Re-enable hover effects
-                el.style.zIndex = ''; // Restore z-index rule (or let hover take over)
-            }
-        });
-    }
+    window.addEventListener('mouseup', () => {
+        if (isDragging) {
+            isDragging = false;
+            el.style.transition = ''; // Re-enable hover effects
+            el.style.zIndex = ''; // Restore z-index rule (or let hover take over)
+        }
+    });
+}
 
-    // Add float animation style if not exists
-    if (!document.getElementById('anim-float')) {
-        const style = document.createElement('style');
-        style.id = 'anim-float';
-        style.innerHTML = `
+// Add float animation style if not exists
+if (!document.getElementById('anim-float')) {
+    const style = document.createElement('style');
+    style.id = 'anim-float';
+    style.innerHTML = `
             @keyframes float {
 
                 0 %, 100 % { transform: translateY(0) scale(1); }
@@ -1043,233 +1086,233 @@ export function setupInstructorEvents() {
 }
 }
             `;
-        document.head.appendChild(style);
+    document.head.appendChild(style);
+}
+
+// Gallery Logic
+document.getElementById('btn-open-gallery').addEventListener('click', () => {
+    window.open('monster_preview.html', '_blank');
+});
+
+// Logout Logic
+document.getElementById('logout-btn').addEventListener('click', async () => {
+    if (confirm('確定要登出講師模式嗎？ (將會回到首頁)')) {
+        await signOutUser();
+        sessionStorage.removeItem('vibecoding_instructor_in_room');
+        sessionStorage.removeItem('vibecoding_admin_referer');
+        window.location.hash = '';
+        window.location.reload();
     }
+});
+
+// Check Previous Session (Handled by onAuthStateChanged now)
+// if (sessionStorage.getItem('vibecoding_instructor_auth') === 'true') {
+//     authModal.classList.add('hidden');
+// }
 
-    // Gallery Logic
-    document.getElementById('btn-open-gallery').addEventListener('click', () => {
-        window.open('monster_preview.html', '_blank');
+// Check Active Room State
+const activeRoom = sessionStorage.getItem('vibecoding_instructor_in_room');
+if (activeRoom === 'true' && savedRoomCode) {
+    enterRoom(savedRoomCode);
+}
+
+// Module-level variable to track subscription (Moved to top)
+
+function enterRoom(roomCode) {
+    createContainer.classList.add('hidden');
+    roomInfo.classList.remove('hidden');
+    dashboardContent.classList.remove('hidden');
+    document.getElementById('group-photo-btn').classList.remove('hidden'); // Show photo button
+    displayRoomCode.textContent = roomCode;
+    localStorage.setItem('vibecoding_instructor_room', roomCode);
+    sessionStorage.setItem('vibecoding_instructor_in_room', 'true');
+
+    // Unsubscribe previous if any
+    if (roomUnsubscribe) roomUnsubscribe();
+
+    // Subscribe to updates
+    roomUnsubscribe = subscribeToRoom(roomCode, (students) => {
+        currentStudents = students;
+        renderTransposedHeatmap(students);
     });
+}
 
-    // Logout Logic
-    document.getElementById('logout-btn').addEventListener('click', async () => {
-        if (confirm('確定要登出講師模式嗎？ (將會回到首頁)')) {
-            await signOutUser();
-            sessionStorage.removeItem('vibecoding_instructor_in_room');
-            sessionStorage.removeItem('vibecoding_admin_referer');
-            window.location.hash = '';
-            window.location.reload();
+// Leave Room Logic
+document.getElementById('leave-room-btn').addEventListener('click', () => {
+    if (confirm('確定要離開目前教室嗎？(不會刪除教室資料，僅回到選擇介面)')) {
+        // Unsubscribe
+        if (roomUnsubscribe) {
+            roomUnsubscribe();
+            roomUnsubscribe = null;
         }
-    });
 
-    // Check Previous Session (Handled by onAuthStateChanged now)
-    // if (sessionStorage.getItem('vibecoding_instructor_auth') === 'true') {
-    //     authModal.classList.add('hidden');
-    // }
+        // UI Reset
+        createContainer.classList.remove('hidden');
+        roomInfo.classList.add('hidden');
+        dashboardContent.classList.add('hidden');
+        document.getElementById('group-photo-btn').classList.add('hidden'); // Hide photo button
 
-    // Check Active Room State
-    const activeRoom = sessionStorage.getItem('vibecoding_instructor_in_room');
-    if (activeRoom === 'true' && savedRoomCode) {
-        enterRoom(savedRoomCode);
+        // Clear Data Display
+        document.getElementById('heatmap-body').innerHTML = '<tr><td colspan="100" class="text-center py-10 text-gray-500">等待資料載入...</td></tr>';
+        document.getElementById('heatmap-header').innerHTML = '<th class="p-3 text-left sticky left-0 bg-gray-800 z-20 border-b border-gray-700 min-w-[150px]">學員 / 關卡</th>';
+
+        // State Clear
+        sessionStorage.removeItem('vibecoding_instructor_in_room');
+        localStorage.removeItem('vibecoding_instructor_room');
     }
+});
+
+// Modal Events
+window.showBroadcastModal = (userId, challengeId) => {
+    const modal = document.getElementById('broadcast-modal');
+    const content = document.getElementById('broadcast-content');
 
-    // Module-level variable to track subscription (Moved to top)
+    // Find Data
+    const student = currentStudents.find(s => s.id === userId);
+    if (!student) return alert('找不到學員資料');
 
-    function enterRoom(roomCode) {
-        createContainer.classList.add('hidden');
-        roomInfo.classList.remove('hidden');
-        dashboardContent.classList.remove('hidden');
-        document.getElementById('group-photo-btn').classList.remove('hidden'); // Show photo button
-        displayRoomCode.textContent = roomCode;
-        localStorage.setItem('vibecoding_instructor_room', roomCode);
-        sessionStorage.setItem('vibecoding_instructor_in_room', 'true');
+    const p = student.progress ? student.progress[challengeId] : null;
+    if (!p) return alert('找不到該作品資料');
 
-        // Unsubscribe previous if any
-        if (roomUnsubscribe) roomUnsubscribe();
+    const challenge = cachedChallenges.find(c => c.id === challengeId);
+    const title = challenge ? challenge.title : '未知題目';
 
-        // Subscribe to updates
-        roomUnsubscribe = subscribeToRoom(roomCode, (students) => {
-            currentStudents = students;
-            renderTransposedHeatmap(students);
-        });
-    }
+    // Populate UI
+    document.getElementById('broadcast-avatar').textContent = student.nickname[0] || '?';
+    document.getElementById('broadcast-author').textContent = student.nickname;
+    document.getElementById('broadcast-challenge').textContent = title;
+    document.getElementById('broadcast-prompt').textContent = p.prompt || '(無內容)';
 
-    // Leave Room Logic
-    document.getElementById('leave-room-btn').addEventListener('click', () => {
-        if (confirm('確定要離開目前教室嗎？(不會刪除教室資料，僅回到選擇介面)')) {
-            // Unsubscribe
-            if (roomUnsubscribe) {
-                roomUnsubscribe();
-                roomUnsubscribe = null;
-            }
+    // Store IDs for Actions (Reject/BroadcastAll)
+    modal.dataset.userId = userId;
+    modal.dataset.challengeId = challengeId;
 
-            // UI Reset
-            createContainer.classList.remove('hidden');
-            roomInfo.classList.add('hidden');
-            dashboardContent.classList.add('hidden');
-            document.getElementById('group-photo-btn').classList.add('hidden'); // Hide photo button
+    // Show
+    modal.classList.remove('hidden');
+    setTimeout(() => {
+        content.classList.remove('scale-95', 'opacity-0');
+        content.classList.add('opacity-100', 'scale-100');
+    }, 10);
+};
 
-            // Clear Data Display
-            document.getElementById('heatmap-body').innerHTML = '<tr><td colspan="100" class="text-center py-10 text-gray-500">等待資料載入...</td></tr>';
-            document.getElementById('heatmap-header').innerHTML = '<th class="p-3 text-left sticky left-0 bg-gray-800 z-20 border-b border-gray-700 min-w-[150px]">學員 / 關卡</th>';
+window.closeBroadcast = () => {
+    const modal = document.getElementById('broadcast-modal');
+    const content = document.getElementById('broadcast-content');
+    content.classList.remove('opacity-100', 'scale-100');
+    content.classList.add('scale-95', 'opacity-0');
+    setTimeout(() => modal.classList.add('hidden'), 300);
+};
 
-            // State Clear
-            sessionStorage.removeItem('vibecoding_instructor_in_room');
-            localStorage.removeItem('vibecoding_instructor_room');
-        }
-    });
+window.openStage = (prompt, author) => {
+    document.getElementById('broadcast-content').classList.add('hidden');
+    const stage = document.getElementById('stage-view');
+    stage.classList.remove('hidden');
+    document.getElementById('stage-prompt').textContent = prompt;
+    document.getElementById('stage-author').textContent = author;
+};
 
-    // Modal Events
-    window.showBroadcastModal = (userId, challengeId) => {
-        const modal = document.getElementById('broadcast-modal');
-        const content = document.getElementById('broadcast-content');
-
-        // Find Data
-        const student = currentStudents.find(s => s.id === userId);
-        if (!student) return alert('找不到學員資料');
-
-        const p = student.progress ? student.progress[challengeId] : null;
-        if (!p) return alert('找不到該作品資料');
-
-        const challenge = cachedChallenges.find(c => c.id === challengeId);
-        const title = challenge ? challenge.title : '未知題目';
-
-        // Populate UI
-        document.getElementById('broadcast-avatar').textContent = student.nickname[0] || '?';
-        document.getElementById('broadcast-author').textContent = student.nickname;
-        document.getElementById('broadcast-challenge').textContent = title;
-        document.getElementById('broadcast-prompt').textContent = p.prompt || '(無內容)';
-
-        // Store IDs for Actions (Reject/BroadcastAll)
-        modal.dataset.userId = userId;
-        modal.dataset.challengeId = challengeId;
-
-        // Show
-        modal.classList.remove('hidden');
-        setTimeout(() => {
-            content.classList.remove('scale-95', 'opacity-0');
-            content.classList.add('opacity-100', 'scale-100');
-        }, 10);
-    };
+window.closeStage = () => {
+    document.getElementById('stage-view').classList.add('hidden');
+    document.getElementById('broadcast-content').classList.remove('hidden');
+};
 
-    window.closeBroadcast = () => {
-        const modal = document.getElementById('broadcast-modal');
-        const content = document.getElementById('broadcast-content');
-        content.classList.remove('opacity-100', 'scale-100');
-        content.classList.add('scale-95', 'opacity-0');
-        setTimeout(() => modal.classList.add('hidden'), 300);
-    };
+document.getElementById('btn-show-stage').addEventListener('click', () => {
+    const prompt = document.getElementById('broadcast-prompt').textContent;
+    const author = document.getElementById('broadcast-author').textContent;
+    window.openStage(prompt, author);
+});
 
-    window.openStage = (prompt, author) => {
-        document.getElementById('broadcast-content').classList.add('hidden');
-        const stage = document.getElementById('stage-view');
-        stage.classList.remove('hidden');
-        document.getElementById('stage-prompt').textContent = prompt;
-        document.getElementById('stage-author').textContent = author;
-    };
+// Reject Logic
+document.getElementById('btn-reject-task').addEventListener('click', async () => {
+    if (!confirm('確定要退回此題目讓學員重做嗎？')) return;
 
-    window.closeStage = () => {
-        document.getElementById('stage-view').classList.add('hidden');
-        document.getElementById('broadcast-content').classList.remove('hidden');
-    };
+    // We need student ID (userId) and Challenge ID.
+    // Currently showBroadcastModal only receives nickname, title, prompt.
+    // We need to attach data-userid and data-challengeid to the modal.
+    const modal = document.getElementById('broadcast-modal');
+    const userId = modal.dataset.userId;
+    const challengeId = modal.dataset.challengeId;
+    const roomCode = localStorage.getItem('vibecoding_instructor_room');
 
-    document.getElementById('btn-show-stage').addEventListener('click', () => {
-        const prompt = document.getElementById('broadcast-prompt').textContent;
-        const author = document.getElementById('broadcast-author').textContent;
-        window.openStage(prompt, author);
-    });
+    if (userId && challengeId && roomCode) {
+        try {
+            await resetProgress(userId, roomCode, challengeId);
+            // Close modal
+            window.closeBroadcast();
+        } catch (e) {
+            console.error(e);
+            alert('退回失敗');
+        }
+    }
+});
+// Prompt Viewer Logic
+window.openPromptList = (type, id, title) => {
+    const modal = document.getElementById('prompt-list-modal');
+    const container = document.getElementById('prompt-list-container');
+    const titleEl = document.getElementById('prompt-list-title');
 
-    // Reject Logic
-    document.getElementById('btn-reject-task').addEventListener('click', async () => {
-        if (!confirm('確定要退回此題目讓學員重做嗎？')) return;
+    titleEl.textContent = type === 'student' ? `${title} 的所有提示詞` : `題目：${title} 的所有作品`;
 
-        // We need student ID (userId) and Challenge ID.
-        // Currently showBroadcastModal only receives nickname, title, prompt.
-        // We need to attach data-userid and data-challengeid to the modal.
-        const modal = document.getElementById('broadcast-modal');
-        const userId = modal.dataset.userId;
-        const challengeId = modal.dataset.challengeId;
-        const roomCode = localStorage.getItem('vibecoding_instructor_room');
+    // Reset Anonymous Toggle in List View
+    const anonCheck = document.getElementById('list-anonymous-toggle');
+    if (anonCheck) anonCheck.checked = false;
 
-        if (userId && challengeId && roomCode) {
-            try {
-                await resetProgress(userId, roomCode, challengeId);
-                // Close modal
-                window.closeBroadcast();
-            } catch (e) {
-                console.error(e);
-                alert('退回失敗');
-            }
+    container.innerHTML = '';
+    modal.classList.remove('hidden');
+
+    // Collect Prompts
+    let prompts = [];
+    // Fix: Reset selection when opening new list to prevent cross-contamination
+    selectedPrompts = [];
+    updateCompareButton();
+
+    if (type === 'student') {
+        const student = currentStudents.find(s => s.id === id);
+        if (student && student.progress) {
+            prompts = Object.entries(student.progress)
+                .filter(([_, p]) => p.status === 'completed' && p.prompt)
+                .map(([challengeId, p]) => {
+                    const challenge = cachedChallenges.find(c => c.id === challengeId);
+                    return {
+                        id: `${student.id}_${challengeId}`,
+                        title: challenge ? challenge.title : '未知題目',
+                        prompt: p.prompt,
+                        author: student.nickname,
+                        studentId: student.id,
+                        challengeId: challengeId,
+                        time: p.completedAt ? new Date(p.completedAt.seconds * 1000).toLocaleString() : ''
+                    };
+                });
         }
-    });
-    // Prompt Viewer Logic
-    window.openPromptList = (type, id, title) => {
-        const modal = document.getElementById('prompt-list-modal');
-        const container = document.getElementById('prompt-list-container');
-        const titleEl = document.getElementById('prompt-list-title');
-
-        titleEl.textContent = type === 'student' ? `${title} 的所有提示詞` : `題目：${title} 的所有作品`;
-
-        // Reset Anonymous Toggle in List View
-        const anonCheck = document.getElementById('list-anonymous-toggle');
-        if (anonCheck) anonCheck.checked = false;
-
-        container.innerHTML = '';
-        modal.classList.remove('hidden');
-
-        // Collect Prompts
-        let prompts = [];
-        // Fix: Reset selection when opening new list to prevent cross-contamination
-        selectedPrompts = [];
-        updateCompareButton();
-
-        if (type === 'student') {
-            const student = currentStudents.find(s => s.id === id);
-            if (student && student.progress) {
-                prompts = Object.entries(student.progress)
-                    .filter(([_, p]) => p.status === 'completed' && p.prompt)
-                    .map(([challengeId, p]) => {
-                        const challenge = cachedChallenges.find(c => c.id === challengeId);
-                        return {
-                            id: `${student.id}_${challengeId}`,
-                            title: challenge ? challenge.title : '未知題目',
-                            prompt: p.prompt,
-                            author: student.nickname,
-                            studentId: student.id,
-                            challengeId: challengeId,
-                            time: p.completedAt ? new Date(p.completedAt.seconds * 1000).toLocaleString() : ''
-                        };
+    } else if (type === 'challenge') {
+        currentStudents.forEach(student => {
+            if (student.progress && student.progress[id]) {
+                const p = student.progress[id];
+                if (p.status === 'completed' && p.prompt) {
+                    prompts.push({
+                        id: `${student.id}_${id}`,
+                        title: student.nickname, // When viewing challenge, title is student name
+                        prompt: p.prompt,
+                        author: student.nickname,
+                        studentId: student.id,
+                        challengeId: id,
+                        time: p.completedAt ? new Date(p.completedAt.seconds * 1000).toLocaleString() : ''
                     });
-            }
-        } else if (type === 'challenge') {
-            currentStudents.forEach(student => {
-                if (student.progress && student.progress[id]) {
-                    const p = student.progress[id];
-                    if (p.status === 'completed' && p.prompt) {
-                        prompts.push({
-                            id: `${student.id}_${id}`,
-                            title: student.nickname, // When viewing challenge, title is student name
-                            prompt: p.prompt,
-                            author: student.nickname,
-                            studentId: student.id,
-                            challengeId: id,
-                            time: p.completedAt ? new Date(p.completedAt.seconds * 1000).toLocaleString() : ''
-                        });
-                    }
                 }
-            });
-        }
+            }
+        });
+    }
 
-        if (prompts.length === 0) {
-            container.innerHTML = '<div class="col-span-full text-center text-gray-500 py-10">無資料</div>';
-            return;
-        }
+    if (prompts.length === 0) {
+        container.innerHTML = '<div class="col-span-full text-center text-gray-500 py-10">無資料</div>';
+        return;
+    }
 
-        prompts.forEach(p => {
-            const card = document.createElement('div');
-            // Reduced height (h-64 -> h-48) and padding, but larger text inside
-            card.className = 'bg-gray-800 rounded-xl p-3 border border-gray-700 hover:border-cyan-500 transition-colors flex flex-col h-48 group';
-            card.innerHTML = `
+    prompts.forEach(p => {
+        const card = document.createElement('div');
+        // Reduced height (h-64 -> h-48) and padding, but larger text inside
+        card.className = 'bg-gray-800 rounded-xl p-3 border border-gray-700 hover:border-cyan-500 transition-colors flex flex-col h-48 group';
+        card.innerHTML = `
             <div class="flex justify-between items-start mb-1.5">
                 <h3 class="font-bold text-white text-base truncate w-3/4" title="${p.title}">${p.title}</h3>
                 <!-- Checkbox -->
@@ -1290,167 +1333,167 @@ export function setupInstructorEvents() {
                 </div>
             </div>
             `;
-            container.appendChild(card);
-        });
-    };
+        container.appendChild(card);
+    });
+};
 
-    // Helper Actions
-    window.confirmReset = async (userId, challengeId, title) => {
-        if (confirm(`確定要退回 ${title} 嗎？此動作將清除學員目前的進度。`)) {
-            const roomCode = localStorage.getItem('vibecoding_instructor_room');
-            if (userId && challengeId && roomCode) {
-                try {
-                    const { resetProgress } = await import("../services/classroom.js");
-                    await resetProgress(userId, roomCode, challengeId);
-                    // Refresh current list if open? (It will stay open but might not update immediately if realtime check isn't hooked to modal content. But subscriptions update `currentStudents`. We might need to refresh list)
-                    // For now, simple alert or auto-close
-                    alert("已退回");
-                    // close modal to refresh data context
-                    document.getElementById('prompt-list-modal').classList.add('hidden');
-                } catch (e) {
-                    console.error(e);
-                    alert("退回失敗");
-                }
+// Helper Actions
+window.confirmReset = async (userId, challengeId, title) => {
+    if (confirm(`確定要退回 ${title} 嗎？此動作將清除學員目前的進度。`)) {
+        const roomCode = localStorage.getItem('vibecoding_instructor_room');
+        if (userId && challengeId && roomCode) {
+            try {
+                const { resetProgress } = await import("../services/classroom.js");
+                await resetProgress(userId, roomCode, challengeId);
+                // Refresh current list if open? (It will stay open but might not update immediately if realtime check isn't hooked to modal content. But subscriptions update `currentStudents`. We might need to refresh list)
+                // For now, simple alert or auto-close
+                alert("已退回");
+                // close modal to refresh data context
+                document.getElementById('prompt-list-modal').classList.add('hidden');
+            } catch (e) {
+                console.error(e);
+                alert("退回失敗");
             }
         }
-    };
-
-    window.broadcastPrompt = (userId, challengeId) => {
-        window.showBroadcastModal(userId, challengeId);
-    };
-
-    // Selection Logic
-    let selectedPrompts = []; // Stores IDs
-
-    window.handlePromptSelection = (checkbox) => {
-        const id = checkbox.dataset.id;
+    }
+};
 
-        if (checkbox.checked) {
-            if (selectedPrompts.length >= 3) {
-                checkbox.checked = false;
-                alert('最多只能選擇 3 個提示詞進行比較');
-                return;
-            }
-            selectedPrompts.push(id);
-        } else {
-            selectedPrompts = selectedPrompts.filter(pid => pid !== id);
-        }
-        updateCompareButton();
-    };
+window.broadcastPrompt = (userId, challengeId) => {
+    window.showBroadcastModal(userId, challengeId);
+};
 
-    function updateCompareButton() {
-        const btn = document.getElementById('btn-compare-prompts');
-        if (!btn) return;
+// Selection Logic
+let selectedPrompts = []; // Stores IDs
 
-        const count = selectedPrompts.length;
-        const span = btn.querySelector('span');
-        if (span) span.textContent = `🔍 比較已選項目 (${count}/3)`;
+window.handlePromptSelection = (checkbox) => {
+    const id = checkbox.dataset.id;
 
-        if (count > 0) {
-            btn.disabled = false;
-            btn.classList.remove('opacity-50', 'cursor-not-allowed');
-        } else {
-            btn.disabled = true;
-            btn.classList.add('opacity-50', 'cursor-not-allowed');
+    if (checkbox.checked) {
+        if (selectedPrompts.length >= 3) {
+            checkbox.checked = false;
+            alert('最多只能選擇 3 個提示詞進行比較');
+            return;
         }
+        selectedPrompts.push(id);
+    } else {
+        selectedPrompts = selectedPrompts.filter(pid => pid !== id);
     }
-    // Comparison Logic
-    const compareBtn = document.getElementById('btn-compare-prompts');
-    if (compareBtn) {
-        compareBtn.addEventListener('click', () => {
-            const dataToCompare = [];
-            selectedPrompts.forEach(fullId => {
-                const lastUnderscore = fullId.lastIndexOf('_');
-                const studentId = fullId.substring(0, lastUnderscore);
-                const challengeId = fullId.substring(lastUnderscore + 1);
-
-                const student = currentStudents.find(s => s.id === studentId);
-                if (student && student.progress && student.progress[challengeId]) {
-                    const p = student.progress[challengeId];
-                    const challenge = cachedChallenges.find(c => c.id === challengeId);
+    updateCompareButton();
+};
 
-                    dataToCompare.push({
-                        title: challenge ? challenge.title : '未知',
-                        author: student.nickname,
-                        prompt: p.prompt,
-                        time: p.completedAt ? new Date(p.completedAt.seconds * 1000).toLocaleTimeString() : ''
-                    });
-                }
-            });
+function updateCompareButton() {
+    const btn = document.getElementById('btn-compare-prompts');
+    if (!btn) return;
 
-            const isAnon = document.getElementById('list-anonymous-toggle')?.checked || false;
-            openComparisonView(dataToCompare, isAnon);
-        });
-    }
+    const count = selectedPrompts.length;
+    const span = btn.querySelector('span');
+    if (span) span.textContent = `🔍 比較已選項目 (${count}/3)`;
 
-    let isAnonymous = false;
-
-    window.toggleAnonymous = (btn) => {
-        isAnonymous = !isAnonymous;
-        btn.textContent = isAnonymous ? '🙈 顯示姓名' : '👀 隱藏姓名';
-        btn.classList.toggle('bg-gray-700');
-        btn.classList.toggle('bg-purple-700');
-
-        // Update DOM
-        document.querySelectorAll('.comparison-author').forEach(el => {
-            if (isAnonymous) {
-                el.dataset.original = el.textContent;
-                el.textContent = '學員';
-                el.classList.add('blur-sm'); // Optional Effect
-                setTimeout(() => el.classList.remove('blur-sm'), 300);
-            } else {
-                if (el.dataset.original) el.textContent = el.dataset.original;
+    if (count > 0) {
+        btn.disabled = false;
+        btn.classList.remove('opacity-50', 'cursor-not-allowed');
+    } else {
+        btn.disabled = true;
+        btn.classList.add('opacity-50', 'cursor-not-allowed');
+    }
+}
+// Comparison Logic
+const compareBtn = document.getElementById('btn-compare-prompts');
+if (compareBtn) {
+    compareBtn.addEventListener('click', () => {
+        const dataToCompare = [];
+        selectedPrompts.forEach(fullId => {
+            const lastUnderscore = fullId.lastIndexOf('_');
+            const studentId = fullId.substring(0, lastUnderscore);
+            const challengeId = fullId.substring(lastUnderscore + 1);
+
+            const student = currentStudents.find(s => s.id === studentId);
+            if (student && student.progress && student.progress[challengeId]) {
+                const p = student.progress[challengeId];
+                const challenge = cachedChallenges.find(c => c.id === challengeId);
+
+                dataToCompare.push({
+                    title: challenge ? challenge.title : '未知',
+                    author: student.nickname,
+                    prompt: p.prompt,
+                    time: p.completedAt ? new Date(p.completedAt.seconds * 1000).toLocaleTimeString() : ''
+                });
             }
         });
-    };
 
-    window.openComparisonView = (items, initialAnonymous = false) => {
-        const modal = document.getElementById('comparison-modal');
-        const grid = document.getElementById('comparison-grid');
+        const isAnon = document.getElementById('list-anonymous-toggle')?.checked || false;
+        openComparisonView(dataToCompare, isAnon);
+    });
+}
+
+let isAnonymous = false;
+
+window.toggleAnonymous = (btn) => {
+    isAnonymous = !isAnonymous;
+    btn.textContent = isAnonymous ? '🙈 顯示姓名' : '👀 隱藏姓名';
+    btn.classList.toggle('bg-gray-700');
+    btn.classList.toggle('bg-purple-700');
+
+    // Update DOM
+    document.querySelectorAll('.comparison-author').forEach(el => {
+        if (isAnonymous) {
+            el.dataset.original = el.textContent;
+            el.textContent = '學員';
+            el.classList.add('blur-sm'); // Optional Effect
+            setTimeout(() => el.classList.remove('blur-sm'), 300);
+        } else {
+            if (el.dataset.original) el.textContent = el.dataset.original;
+        }
+    });
+};
+
+window.openComparisonView = (items, initialAnonymous = false) => {
+    const modal = document.getElementById('comparison-modal');
+    const grid = document.getElementById('comparison-grid');
 
-        // Apply Anonymous State
-        isAnonymous = initialAnonymous;
-        const anonBtn = document.getElementById('btn-anonymous-toggle');
+    // Apply Anonymous State
+    isAnonymous = initialAnonymous;
+    const anonBtn = document.getElementById('btn-anonymous-toggle');
 
-        // Update Toggle UI to match state
-        if (anonBtn) {
-            if (isAnonymous) {
-                anonBtn.textContent = '🙈 顯示姓名';
-                anonBtn.classList.add('bg-purple-700');
-                anonBtn.classList.remove('bg-gray-700');
-            } else {
-                anonBtn.textContent = '👀 隱藏姓名';
-                anonBtn.classList.remove('bg-purple-700');
-                anonBtn.classList.add('bg-gray-700');
-            }
+    // Update Toggle UI to match state
+    if (anonBtn) {
+        if (isAnonymous) {
+            anonBtn.textContent = '🙈 顯示姓名';
+            anonBtn.classList.add('bg-purple-700');
+            anonBtn.classList.remove('bg-gray-700');
+        } else {
+            anonBtn.textContent = '👀 隱藏姓名';
+            anonBtn.classList.remove('bg-purple-700');
+            anonBtn.classList.add('bg-gray-700');
         }
+    }
 
-        // Setup Grid Rows (Vertical Stacking)
-        let rowClass = 'grid-rows-1';
-        if (items.length === 2) rowClass = 'grid-rows-2';
-        if (items.length === 3) rowClass = 'grid-rows-3';
-
-        grid.className = `absolute inset-0 grid ${rowClass} gap-0 divide-y divide-gray-600`;
-        grid.innerHTML = '';
-
-        items.forEach(item => {
-            const col = document.createElement('div');
-            // Check overflow-hidden to keep it contained, use flex-row for compact header + content
-            col.className = 'flex flex-row h-full bg-gray-900 p-4 overflow-hidden';
-
-            // Logic for anonymous
-            let displayAuthor = item.author;
-            let blurClass = '';
-
-            if (isAnonymous) {
-                displayAuthor = '學員';
-                blurClass = 'blur-sm'; // Initial blur
-                // Auto remove blur after delay if needed, or keep it? 
-                // Toggle logic removes it after delay. But initial render should probably just be static '學員' or blurred.
-                // The toggle logic uses dataset.original. We need to set it here too.
-            }
+    // Setup Grid Rows (Vertical Stacking)
+    let rowClass = 'grid-rows-1';
+    if (items.length === 2) rowClass = 'grid-rows-2';
+    if (items.length === 3) rowClass = 'grid-rows-3';
+
+    grid.className = `absolute inset-0 grid ${rowClass} gap-0 divide-y divide-gray-600`;
+    grid.innerHTML = '';
+
+    items.forEach(item => {
+        const col = document.createElement('div');
+        // Check overflow-hidden to keep it contained, use flex-row for compact header + content
+        col.className = 'flex flex-row h-full bg-gray-900 p-4 overflow-hidden';
+
+        // Logic for anonymous
+        let displayAuthor = item.author;
+        let blurClass = '';
+
+        if (isAnonymous) {
+            displayAuthor = '學員';
+            blurClass = 'blur-sm'; // Initial blur
+            // Auto remove blur after delay if needed, or keep it? 
+            // Toggle logic removes it after delay. But initial render should probably just be static '學員' or blurred.
+            // The toggle logic uses dataset.original. We need to set it here too.
+        }
 
-            col.innerHTML = `
+        col.innerHTML = `
             <div class="w-48 flex-shrink-0 border-r border-gray-700 pr-4 mr-4 flex flex-col justify-center">
                 <h3 class="text-xl font-bold text-cyan-400 mb-1 comparison-author ${blurClass}" data-original="${item.author}">${displayAuthor}</h3>
                 <p class="text-md text-gray-400 truncate" title="${item.title}">${item.title}</p>
@@ -1460,181 +1503,181 @@ export function setupInstructorEvents() {
                 ${item.prompt}
             </div>
             `;
-            grid.appendChild(col);
-
-            // If blurred, remove blur after animation purely for effect, or keep?
-            // User intention "Hidden Name" usually means "Replaced by generic name".
-            // The blur effect in toggle logic was transient.
-            // If we want persistent anonymity, just "學員" is enough.
-            // The existing toggle logic adds 'blur-sm' then removes it in 300ms.
-            // We should replicate that effect if we want consistency, or just skip blur on init.
-            if (isAnonymous) {
-                const el = col.querySelector('.comparison-author');
-                setTimeout(() => el.classList.remove('blur-sm'), 300);
-            }
-        });
+        grid.appendChild(col);
+
+        // If blurred, remove blur after animation purely for effect, or keep?
+        // User intention "Hidden Name" usually means "Replaced by generic name".
+        // The blur effect in toggle logic was transient.
+        // If we want persistent anonymity, just "學員" is enough.
+        // The existing toggle logic adds 'blur-sm' then removes it in 300ms.
+        // We should replicate that effect if we want consistency, or just skip blur on init.
+        if (isAnonymous) {
+            const el = col.querySelector('.comparison-author');
+            setTimeout(() => el.classList.remove('blur-sm'), 300);
+        }
+    });
+
+    document.getElementById('prompt-list-modal').classList.add('hidden');
+    modal.classList.remove('hidden');
+
+    // Init Canvas (Phase 3)
+    setTimeout(setupCanvas, 100);
+};
 
-        document.getElementById('prompt-list-modal').classList.add('hidden');
-        modal.classList.remove('hidden');
+window.closeComparison = () => {
+    document.getElementById('comparison-modal').classList.add('hidden');
+    clearCanvas();
+};
 
-        // Init Canvas (Phase 3)
-        setTimeout(setupCanvas, 100);
+// --- Phase 3 & 6: Annotation Tools ---
+let canvas, ctx;
+let isDrawing = false;
+let currentPenColor = '#ef4444'; // Red default
+let currentLineWidth = 3;
+let currentMode = 'source-over'; // 'source-over' (Pen) or 'destination-out' (Eraser)
+
+window.setupCanvas = () => {
+    canvas = document.getElementById('annotation-canvas');
+    const container = document.getElementById('comparison-container');
+    if (!canvas || !container) return;
+
+    ctx = canvas.getContext('2d');
+
+    // Resize
+    const resize = () => {
+        canvas.width = container.clientWidth;
+        canvas.height = container.clientHeight;
+        ctx.lineCap = 'round';
+        ctx.lineJoin = 'round';
+        ctx.strokeStyle = currentPenColor;
+        ctx.lineWidth = currentLineWidth;
+        ctx.globalCompositeOperation = currentMode;
     };
+    resize();
+    window.addEventListener('resize', resize);
+
+    // Init Size UI & Cursor
+    updateSizeBtnUI();
+    updateCursorStyle();
+
+    // Cursor Logic
+    const cursor = document.getElementById('tool-cursor');
+
+    canvas.addEventListener('mouseenter', () => cursor.classList.remove('hidden'));
+    canvas.addEventListener('mouseleave', () => cursor.classList.add('hidden'));
+    canvas.addEventListener('mousemove', (e) => {
+        const { x, y } = getPos(e);
+        cursor.style.left = `${x}px`;
+        cursor.style.top = `${y}px`;
+    });
+
+    // Drawing Events
+    const start = (e) => {
+        isDrawing = true;
+        ctx.beginPath();
 
-    window.closeComparison = () => {
-        document.getElementById('comparison-modal').classList.add('hidden');
-        clearCanvas();
+        // Re-apply settings (state might change)
+        ctx.globalCompositeOperation = currentMode;
+        ctx.strokeStyle = currentPenColor;
+        ctx.lineWidth = currentLineWidth;
+
+        const { x, y } = getPos(e);
+        ctx.moveTo(x, y);
     };
 
-    // --- Phase 3 & 6: Annotation Tools ---
-    let canvas, ctx;
-    let isDrawing = false;
-    let currentPenColor = '#ef4444'; // Red default
-    let currentLineWidth = 3;
-    let currentMode = 'source-over'; // 'source-over' (Pen) or 'destination-out' (Eraser)
-
-    window.setupCanvas = () => {
-        canvas = document.getElementById('annotation-canvas');
-        const container = document.getElementById('comparison-container');
-        if (!canvas || !container) return;
-
-        ctx = canvas.getContext('2d');
-
-        // Resize
-        const resize = () => {
-            canvas.width = container.clientWidth;
-            canvas.height = container.clientHeight;
-            ctx.lineCap = 'round';
-            ctx.lineJoin = 'round';
-            ctx.strokeStyle = currentPenColor;
-            ctx.lineWidth = currentLineWidth;
-            ctx.globalCompositeOperation = currentMode;
-        };
-        resize();
-        window.addEventListener('resize', resize);
-
-        // Init Size UI & Cursor
-        updateSizeBtnUI();
-        updateCursorStyle();
-
-        // Cursor Logic
-        const cursor = document.getElementById('tool-cursor');
-
-        canvas.addEventListener('mouseenter', () => cursor.classList.remove('hidden'));
-        canvas.addEventListener('mouseleave', () => cursor.classList.add('hidden'));
-        canvas.addEventListener('mousemove', (e) => {
-            const { x, y } = getPos(e);
-            cursor.style.left = `${x}px`;
-            cursor.style.top = `${y}px`;
-        });
+    const move = (e) => {
+        if (!isDrawing) return;
+        const { x, y } = getPos(e);
+        ctx.lineTo(x, y);
+        ctx.stroke();
+    };
 
-        // Drawing Events
-        const start = (e) => {
-            isDrawing = true;
-            ctx.beginPath();
-
-            // Re-apply settings (state might change)
-            ctx.globalCompositeOperation = currentMode;
-            ctx.strokeStyle = currentPenColor;
-            ctx.lineWidth = currentLineWidth;
-
-            const { x, y } = getPos(e);
-            ctx.moveTo(x, y);
-        };
-
-        const move = (e) => {
-            if (!isDrawing) return;
-            const { x, y } = getPos(e);
-            ctx.lineTo(x, y);
-            ctx.stroke();
-        };
-
-        const end = () => {
-            isDrawing = false;
-        };
-
-        canvas.onmousedown = start;
-        canvas.onmousemove = move;
-        canvas.onmouseup = end;
-        canvas.onmouseleave = end;
-
-        // Touch support
-        canvas.ontouchstart = (e) => { e.preventDefault(); start(e.touches[0]); };
-        canvas.ontouchmove = (e) => { e.preventDefault(); move(e.touches[0]); };
-        canvas.ontouchend = (e) => { e.preventDefault(); end(); };
+    const end = () => {
+        isDrawing = false;
     };
 
-    function getPos(e) {
-        const rect = canvas.getBoundingClientRect();
-        return {
-            x: e.clientX - rect.left,
-            y: e.clientY - rect.top
-        };
-    }
+    canvas.onmousedown = start;
+    canvas.onmousemove = move;
+    canvas.onmouseup = end;
+    canvas.onmouseleave = end;
 
-    // Unified Tool Handler
-    window.setPenTool = (tool, color, btn) => {
-        // UI Update
-        document.querySelectorAll('.annotation-tool').forEach(b => {
-            b.classList.remove('ring-white');
-            b.classList.add('ring-transparent');
-        });
-        btn.classList.remove('ring-transparent');
-        btn.classList.add('ring-white');
+    // Touch support
+    canvas.ontouchstart = (e) => { e.preventDefault(); start(e.touches[0]); };
+    canvas.ontouchmove = (e) => { e.preventDefault(); move(e.touches[0]); };
+    canvas.ontouchend = (e) => { e.preventDefault(); end(); };
+};
 
-        if (tool === 'eraser') {
-            currentMode = 'destination-out';
-        } else {
-            currentMode = 'source-over';
-            currentPenColor = color;
-        }
-        updateCursorStyle();
+function getPos(e) {
+    const rect = canvas.getBoundingClientRect();
+    return {
+        x: e.clientX - rect.left,
+        y: e.clientY - rect.top
     };
+}
 
-    // Size Handler
-    window.setPenSize = (size, btn) => {
-        currentLineWidth = size;
-        updateSizeBtnUI();
-        updateCursorStyle();
-    };
+// Unified Tool Handler
+window.setPenTool = (tool, color, btn) => {
+    // UI Update
+    document.querySelectorAll('.annotation-tool').forEach(b => {
+        b.classList.remove('ring-white');
+        b.classList.add('ring-transparent');
+    });
+    btn.classList.remove('ring-transparent');
+    btn.classList.add('ring-white');
+
+    if (tool === 'eraser') {
+        currentMode = 'destination-out';
+    } else {
+        currentMode = 'source-over';
+        currentPenColor = color;
+    }
+    updateCursorStyle();
+};
 
-    function updateCursorStyle() {
-        const cursor = document.getElementById('tool-cursor');
-        if (!cursor) return;
+// Size Handler
+window.setPenSize = (size, btn) => {
+    currentLineWidth = size;
+    updateSizeBtnUI();
+    updateCursorStyle();
+};
 
-        // Size
-        cursor.style.width = `${currentLineWidth}px`;
-        cursor.style.height = `${currentLineWidth}px`;
+function updateCursorStyle() {
+    const cursor = document.getElementById('tool-cursor');
+    if (!cursor) return;
+
+    // Size
+    cursor.style.width = `${currentLineWidth}px`;
+    cursor.style.height = `${currentLineWidth}px`;
+
+    // Color
+    if (currentMode === 'destination-out') {
+        // Eraser: White solid
+        cursor.style.backgroundColor = 'white';
+        cursor.style.borderColor = '#999';
+    } else {
+        // Pen: Tool color
+        cursor.style.backgroundColor = currentPenColor;
+        cursor.style.borderColor = 'rgba(255,255,255,0.8)';
+    }
+}
 
-        // Color
-        if (currentMode === 'destination-out') {
-            // Eraser: White solid
-            cursor.style.backgroundColor = 'white';
-            cursor.style.borderColor = '#999';
+function updateSizeBtnUI() {
+    document.querySelectorAll('.size-btn').forEach(b => {
+        if (parseInt(b.dataset.size) === currentLineWidth) {
+            b.classList.add('bg-gray-600', 'text-white');
+            b.classList.remove('text-gray-400', 'hover:bg-gray-700');
         } else {
-            // Pen: Tool color
-            cursor.style.backgroundColor = currentPenColor;
-            cursor.style.borderColor = 'rgba(255,255,255,0.8)';
+            b.classList.remove('bg-gray-600', 'text-white');
+            b.classList.add('text-gray-400', 'hover:bg-gray-700');
         }
-    }
+    });
+}
 
-    function updateSizeBtnUI() {
-        document.querySelectorAll('.size-btn').forEach(b => {
-            if (parseInt(b.dataset.size) === currentLineWidth) {
-                b.classList.add('bg-gray-600', 'text-white');
-                b.classList.remove('text-gray-400', 'hover:bg-gray-700');
-            } else {
-                b.classList.remove('bg-gray-600', 'text-white');
-                b.classList.add('text-gray-400', 'hover:bg-gray-700');
-            }
-        });
+window.clearCanvas = () => {
+    if (canvas && ctx) {
+        ctx.clearRect(0, 0, canvas.width, canvas.height);
     }
-
-    window.clearCanvas = () => {
-        if (canvas && ctx) {
-            ctx.clearRect(0, 0, canvas.width, canvas.height);
-        }
-    };
+};
 }
 
 /**