diff --git a/infra/smalruby-classroom/lambda/handler.ts b/infra/smalruby-classroom/lambda/handler.ts
index 0910fc140af..0732b7609da 100644
--- a/infra/smalruby-classroom/lambda/handler.ts
+++ b/infra/smalruby-classroom/lambda/handler.ts
@@ -35,14 +35,16 @@ const CLASSROOM_TTL_SECONDS = CLASSROOM_TTL_DAYS * 24 * 60 * 60;
 // Session and membership TTL matches classroom TTL
 const SESSION_TTL_SECONDS = CLASSROOM_TTL_SECONDS;
 // Rate limiting for join endpoint (per IP)
-const JOIN_RATE_LIMIT_WINDOW_SECONDS = 60;
-const JOIN_RATE_LIMIT_MAX_ATTEMPTS = 50;
+const JOIN_RATE_LIMIT_WINDOW_SECONDS = parseInt(process.env.JOIN_RATE_LIMIT_WINDOW_SECONDS || '60', 10);
+const JOIN_RATE_LIMIT_MAX_ATTEMPTS = parseInt(process.env.JOIN_RATE_LIMIT_MAX_ATTEMPTS || '50', 10);
 const JOIN_CODE_REGEX = new RegExp(`^[${JOIN_CODE_CHARS}]{${JOIN_CODE_LENGTH}}$`);
+// Session activity TTL — determines "seated" status for teachers (default 1 hour)
+const SESSION_ACTIVE_TTL_SECONDS = parseInt(process.env.SESSION_ACTIVE_TTL_SECONDS || '3600', 10);
 // Submission config (TTL matches classroom TTL)
 const SUBMISSION_TTL_SECONDS = CLASSROOM_TTL_SECONDS;
 const MAX_PROJECT_NAME_LENGTH = 100;
-const PRESIGNED_URL_UPLOAD_EXPIRY = 15 * 60; // 15 minutes
-const PRESIGNED_URL_DOWNLOAD_EXPIRY = 60 * 60; // 1 hour
+const PRESIGNED_URL_UPLOAD_EXPIRY = parseInt(process.env.PRESIGNED_URL_UPLOAD_EXPIRY || '900', 10); // default 15 minutes
+const PRESIGNED_URL_DOWNLOAD_EXPIRY = parseInt(process.env.PRESIGNED_URL_DOWNLOAD_EXPIRY || '3600', 10); // default 1 hour
 const MAX_FILE_SIZE = 10 * 1024 * 1024; // 10 MB
 const MAX_SCREENSHOT_COUNT = 20;
 const MAX_TEACHER_COMMENT_LENGTH = 500;
@@ -420,6 +422,7 @@ async function handleJoinClassroom(sourceIp: string, body: Record<string, unknow
         role: 'student',
         sessionToken,
         joinedAt: now,
+        lastActiveAt: now,
         ttl: Math.floor(Date.now() / 1000) + SESSION_TTL_SECONDS,
       },
       ConditionExpression: 'attribute_not_exists(classroomId) AND attribute_not_exists(memberId)',
@@ -486,6 +489,7 @@ async function handleListMembers(teacherSub: string, classroomId: string): Promi
       displayName: item.displayName,
       role: item.role,
       joinedAt: item.joinedAt,
+      lastActiveAt: item.lastActiveAt || null,
       hasSubmission: !!submission,
       submissionStatus: submission?.status || null,
       submittedAt: submission?.submittedAt || null,
@@ -887,8 +891,46 @@ async function handleUpdateSubmission(
 
 async function handleVerifySession(sessionToken: string): Promise<APIGatewayProxyStructuredResultV2> {
   // verifySessionToken will throw AuthError if invalid
-  await verifySessionToken(sessionToken);
-  return { statusCode: 200, body: JSON.stringify({ valid: true }) };
+  const session = await verifySessionToken(sessionToken);
+
+  // Update lastActiveAt and extend TTL on each verify call
+  const now = new Date().toISOString();
+  await docClient.send(new UpdateCommand({
+    TableName: MEMBERSHIPS_TABLE,
+    Key: { classroomId: session.classroomId, memberId: session.memberId },
+    UpdateExpression: 'SET lastActiveAt = :now, ttl = :ttl',
+    ExpressionAttributeValues: {
+      ':now': now,
+      ':ttl': Math.floor(Date.now() / 1000) + SESSION_TTL_SECONDS,
+    },
+  }));
+
+  // Look up latest submission for this member
+  let submission: Record<string, unknown> | null = null;
+  const subResult = await docClient.send(new QueryCommand({
+    TableName: SUBMISSIONS_TABLE,
+    IndexName: 'classroomId-memberId-index',
+    KeyConditionExpression: 'classroomId = :cid AND memberId = :mid',
+    ExpressionAttributeValues: {
+      ':cid': session.classroomId,
+      ':mid': session.memberId,
+    },
+    ScanIndexForward: false,
+    Limit: 1,
+  }));
+  if (subResult.Items && subResult.Items.length > 0) {
+    const item = subResult.Items[0];
+    submission = {
+      status: item.status,
+      submittedAt: item.submittedAt,
+      teacherComment: item.teacherComment || null,
+    };
+  }
+
+  return {
+    statusCode: 200,
+    body: JSON.stringify({ valid: true, submission }),
+  };
 }
 
 // --- Main handler ---
@@ -957,11 +999,27 @@ export const handler = async (event: APIGatewayProxyEventV2): Promise<APIGateway
       result = await handleListMembers(teacherSub, classroomId);
 
     } else if (method === 'DELETE' && /^\/classrooms\/[^/]+\/members\/[^/]+$/.test(path)) {
-      const token = extractBearerToken(event.headers?.authorization);
-      const teacherSub = await verifyGoogleIdToken(token);
       const classroomId = event.pathParameters?.classroomId || '';
       const memberId = event.pathParameters?.memberId || '';
-      result = await handleDeleteMember(teacherSub, classroomId, memberId);
+
+      if (memberId === 'me') {
+        // Student self-removal via sessionToken
+        const token = extractBearerToken(event.headers?.authorization);
+        const session = await verifySessionToken(token);
+        if (session.classroomId !== classroomId) {
+          throw new AuthError('Session does not match this classroom');
+        }
+        await docClient.send(new DeleteCommand({
+          TableName: MEMBERSHIPS_TABLE,
+          Key: { classroomId, memberId: session.memberId },
+        }));
+        result = { statusCode: 204 };
+      } else {
+        // Teacher removal via Google ID token
+        const token = extractBearerToken(event.headers?.authorization);
+        const teacherSub = await verifyGoogleIdToken(token);
+        result = await handleDeleteMember(teacherSub, classroomId, memberId);
+      }
 
     } else if (method === 'POST' && /^\/classrooms\/[^/]+\/submissions$/.test(path)) {
       const token = extractBearerToken(event.headers?.authorization);
diff --git a/infra/smalruby-classroom/lib/classroom-stack.ts b/infra/smalruby-classroom/lib/classroom-stack.ts
index cb47b3ad427..e6b169fcf19 100644
--- a/infra/smalruby-classroom/lib/classroom-stack.ts
+++ b/infra/smalruby-classroom/lib/classroom-stack.ts
@@ -196,6 +196,11 @@ export class ClassroomStack extends cdk.Stack {
         GOOGLE_CLIENT_ID: googleClientId,
         CORS_ALLOWED_ORIGINS: corsOriginsEnv,
         CLASSROOM_TTL_DAYS: String(classroomTtlDays),
+        SESSION_ACTIVE_TTL_SECONDS: process.env.SESSION_ACTIVE_TTL_SECONDS || '3600',
+        PRESIGNED_URL_UPLOAD_EXPIRY: process.env.PRESIGNED_URL_UPLOAD_EXPIRY || '900',
+        PRESIGNED_URL_DOWNLOAD_EXPIRY: process.env.PRESIGNED_URL_DOWNLOAD_EXPIRY || '3600',
+        JOIN_RATE_LIMIT_WINDOW_SECONDS: process.env.JOIN_RATE_LIMIT_WINDOW_SECONDS || '60',
+        JOIN_RATE_LIMIT_MAX_ATTEMPTS: process.env.JOIN_RATE_LIMIT_MAX_ATTEMPTS || '50',
         STAGE: stage,
       },
       bundling: {
diff --git a/package-lock.json b/package-lock.json
index 62dafa15792..7995ef10503 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -15,6 +15,9 @@
         "packages/scratch-vm",
         "packages/scratch-gui"
       ],
+      "dependencies": {
+        "jszip": "^3.10.1"
+      },
       "devDependencies": {
         "@commitlint/cli": "17.8.1",
         "@commitlint/config-conventional": "17.8.1",
@@ -26375,6 +26378,8 @@
     },
     "node_modules/jszip": {
       "version": "3.10.1",
+      "resolved": "https://registry.npmjs.org/jszip/-/jszip-3.10.1.tgz",
+      "integrity": "sha512-xXDvecyTpGLrqFrvkrUSoxxfJI5AH7U8zxxtVclpsUtMCq4JQ290LY8AW5c7Ggnr/Y/oK+bQMbqK2qmtk3pN4g==",
       "license": "(MIT OR GPL-3.0-or-later)",
       "dependencies": {
         "lie": "~3.3.0",
diff --git a/package.json b/package.json
index eea72d070b4..bc4f8c24195 100644
--- a/package.json
+++ b/package.json
@@ -57,5 +57,8 @@
     "npm": "10.9.5",
     "serialport": "^13.0.0",
     "ts-node": "10.9.2"
+  },
+  "dependencies": {
+    "jszip": "^3.10.1"
   }
 }
diff --git a/packages/scratch-gui/src/components/classroom-modal/classroom-modal.css b/packages/scratch-gui/src/components/classroom-modal/classroom-modal.css
index 4addc742510..28d29c442e8 100644
--- a/packages/scratch-gui/src/components/classroom-modal/classroom-modal.css
+++ b/packages/scratch-gui/src/components/classroom-modal/classroom-modal.css
@@ -447,6 +447,24 @@
     margin-left: 0.5rem;
 }
 
+.seated-badge {
+    color: #4c97ff;
+    font-size: 0.7rem;
+    margin-left: 0.5rem;
+    font-weight: bold;
+}
+
+.not-seated-badge {
+    color: #aaa;
+    font-size: 0.7rem;
+    margin-left: 0.5rem;
+}
+
+.seated-label {
+    text-decoration: underline;
+    text-underline-offset: 2px;
+}
+
 .image-carousel {
     display: flex;
     flex-direction: column;
@@ -527,6 +545,44 @@
     background-color: #e67e16;
 }
 
+.refresh-button {
+    background: none;
+    border: 1px solid #d9d9d9;
+    border-radius: 4px;
+    padding: 0.1rem 0.4rem;
+    cursor: pointer;
+    font-size: 0.9rem;
+    color: #575e75;
+    margin-left: auto;
+}
+
+.refresh-button:hover:not(:disabled) {
+    background-color: #f0f0f0;
+}
+
+.refresh-button:disabled {
+    opacity: 0.3;
+    cursor: default;
+}
+
+.teacher-comment-box {
+    background-color: #fff8e1;
+    border: 1px solid #ffcc02;
+    border-radius: 4px;
+    padding: 0.5rem;
+    margin-top: 0.25rem;
+    display: flex;
+    flex-direction: column;
+    gap: 0.25rem;
+}
+
+.teacher-comment-text {
+    font-size: 0.85rem;
+    color: #575e75;
+    white-space: pre-wrap;
+    word-break: break-word;
+}
+
 .submission-detail {
     display: flex;
     gap: 0.5rem;
@@ -638,6 +694,12 @@
     border-top: 1px solid #e0e0e0;
 }
 
+.detail-footer-buttons {
+    display: flex;
+    gap: 0.5rem;
+    flex-wrap: wrap;
+}
+
 .delete-confirm-box {
     background-color: #fff0f3;
     border: 1px solid #ff6680;
diff --git a/packages/scratch-gui/src/components/classroom-modal/classroom-modal.jsx b/packages/scratch-gui/src/components/classroom-modal/classroom-modal.jsx
index 51b51b523ca..7c33c34d0ac 100644
--- a/packages/scratch-gui/src/components/classroom-modal/classroom-modal.jsx
+++ b/packages/scratch-gui/src/components/classroom-modal/classroom-modal.jsx
@@ -46,10 +46,14 @@ const ClassroomModal = ({
     onOpenSubmission,
     onRefreshDetail,
     onReturnSubmission,
+    onDownloadAll,
+    downloadProgress,
     onStartSubmit,
     onConfirmSubmit,
     onCancelSubmit,
     submitProgress,
+    teacherComment,
+    onRefreshStudentStatus,
     thumbnailDataUrl,
     onTeacherLogout,
     classroomState,
@@ -344,6 +348,8 @@ const ClassroomModal = ({
                         onOpenSubmission={onOpenSubmission}
                         onRefresh={onRefreshDetail}
                         onReturnSubmission={onReturnSubmission}
+                        onDownloadAll={onDownloadAll}
+                        downloadProgress={downloadProgress}
                         onSelectMember={onSelectMember}
                         onShowCodeDisplay={onShowCodeDisplay}
                         onToggleCodeFullscreen={onToggleCodeFullscreen}
@@ -531,7 +537,19 @@ const ClassroomModal = ({
                                     className={styles.statusValue}
                                     data-testid="classroom-submit-status"
                                 >
-                                    {classroomState.submissionStatus === 'submitted' ? (
+                                    {classroomState.submissionStatus === 'returned' ? (
+                                        <React.Fragment>
+                                            {'↩ '}
+                                            <FormattedMessage
+                                                defaultMessage="Returned"
+                                                description="Returned status"
+                                                id="gui.classroom.studentStatus.returned"
+                                            />
+                                            {classroomState.lastSubmittedAt && (
+                                                <span>{` (${new Date(classroomState.lastSubmittedAt).toLocaleTimeString()})`}</span>
+                                            )}
+                                        </React.Fragment>
+                                    ) : classroomState.submissionStatus === 'submitted' ? (
                                         <React.Fragment>
                                             {'✓ '}
                                             <FormattedMessage
@@ -551,7 +569,32 @@ const ClassroomModal = ({
                                         />
                                     )}
                                 </span>
+                                <button
+                                    className={styles.refreshButton}
+                                    data-testid="classroom-student-refresh"
+                                    disabled={isLoading}
+                                    onClick={onRefreshStudentStatus}
+                                >
+                                    {'↻'}
+                                </button>
                             </div>
+                            {classroomState.submissionStatus === 'returned' && teacherComment && (
+                                <div
+                                    className={styles.teacherCommentBox}
+                                    data-testid="classroom-status-teacher-comment"
+                                >
+                                    <span className={styles.statusLabel}>
+                                        <FormattedMessage
+                                            defaultMessage="Comment"
+                                            description="Teacher comment label"
+                                            id="gui.classroom.studentStatus.comment"
+                                        />
+                                    </span>
+                                    <span className={styles.teacherCommentText}>
+                                        {teacherComment}
+                                    </span>
+                                </div>
+                            )}
                         </div>
                         <div className={styles.buttonRow}>
                             <button
@@ -560,7 +603,7 @@ const ClassroomModal = ({
                                 disabled={isLoading}
                                 onClick={onStartSubmit}
                             >
-                                {classroomState.submissionStatus === 'submitted' ? (
+                                {classroomState.submissionStatus ? (
                                     <FormattedMessage
                                         defaultMessage="Resubmit"
                                         description="Resubmit button"
@@ -917,6 +960,8 @@ const TeacherClassDetail = ({
     onOpenSubmission,
     onRefresh,
     onReturnSubmission,
+    onDownloadAll,
+    downloadProgress,
     onShowCodeDisplay,
     onCloseCodeDisplay,
     onCopyInviteLink,
@@ -1012,7 +1057,13 @@ const TeacherClassDetail = ({
         onCloseCodeDisplay();
     }, [onCloseCodeDisplay]);
 
-    const joinedCount = members.length;
+    const isSeated = useCallback(member => {
+        if (!member || !member.lastActiveAt) return false;
+        const elapsed = Date.now() - new Date(member.lastActiveAt).getTime();
+        return elapsed < 60 * 60 * 1000; // 1 hour
+    }, []);
+
+    const joinedCount = members.filter(m => !m.left).length;
     const totalCount = selectedClassroom.studentCount;
 
     // Pre-compute selected member's derived data for the right pane
@@ -1023,8 +1074,9 @@ const TeacherClassDetail = ({
             ...member,
             allImages: [member.thumbnailUrl, ...(member.screenshotUrls || [])].filter(Boolean),
             isReturned: member.submissionStatus === 'returned',
+            isSeated: isSeated(member),
         };
-    }, [selectedMember, memberMap]);
+    }, [selectedMember, memberMap, isSeated]);
 
     return (
         <div className={styles.detailLayout} data-testid="classroom-phase-teacher-detail">
@@ -1152,6 +1204,7 @@ const TeacherClassDetail = ({
                                                 cellColorClass = styles.memberCellJoined;
                                             }
                                         }
+                                        const seated = isSeated(member);
                                         const cellClass = `${styles.memberCell} ${cellColorClass} ${isSelected ? styles.memberCellSelected : ''}`;
                                         let cellLabel = seatNum;
                                         if (isReturned) cellLabel = `↩${seatNum}`;
@@ -1164,7 +1217,9 @@ const TeacherClassDetail = ({
                                                 key={memberId}
                                                 onClick={member ? handleCellClick : null}
                                             >
-                                                {cellLabel}
+                                                {seated ? (
+                                                    <span className={styles.seatedLabel}>{cellLabel}</span>
+                                                ) : cellLabel}
                                             </button>
                                         );
                                     })}
@@ -1208,18 +1263,36 @@ const TeacherClassDetail = ({
                                         </div>
                                     </div>
                                 ) : (
-                                    <button
-                                        className={styles.dangerButton}
-                                        data-testid="classroom-delete-classroom"
-                                        disabled={isLoading}
-                                        onClick={handleDeleteClick}
-                                    >
-                                        <FormattedMessage
-                                            defaultMessage="Delete Classroom"
-                                            description="Delete classroom button"
-                                            id="gui.classroom.teacherDetail.deleteClassroom"
-                                        />
-                                    </button>
+                                    <div className={styles.detailFooterButtons}>
+                                        <button
+                                            className={styles.dangerButton}
+                                            data-testid="classroom-delete-classroom"
+                                            disabled={isLoading}
+                                            onClick={handleDeleteClick}
+                                        >
+                                            <FormattedMessage
+                                                defaultMessage="Delete Classroom"
+                                                description="Delete classroom button"
+                                                id="gui.classroom.teacherDetail.deleteClassroom"
+                                            />
+                                        </button>
+                                        <button
+                                            className={styles.secondaryButton}
+                                            data-testid="classroom-download-all"
+                                            disabled={isLoading || !!downloadProgress}
+                                            onClick={onDownloadAll}
+                                        >
+                                            {downloadProgress ? (
+                                                `${downloadProgress.current}/${downloadProgress.total}`
+                                            ) : (
+                                                <FormattedMessage
+                                                    defaultMessage="Download All"
+                                                    description="Download all submissions button"
+                                                    id="gui.classroom.teacherDetail.downloadAll"
+                                                />
+                                            )}
+                                        </button>
+                                    </div>
                                 )}
                             </div>
                         </div>
@@ -1255,6 +1328,24 @@ const TeacherClassDetail = ({
                                                 {new Date(selectedMemberData.submittedAt).toLocaleTimeString()}
                                             </span>
                                         )}
+                                        <span
+                                            className={selectedMemberData.isSeated ? styles.seatedBadge : styles.notSeatedBadge}
+                                            data-testid="classroom-member-detail-seated"
+                                        >
+                                            {selectedMemberData.isSeated ? (
+                                                <FormattedMessage
+                                                    defaultMessage="Seated"
+                                                    description="Student is currently seated"
+                                                    id="gui.classroom.teacherDetail.seated"
+                                                />
+                                            ) : (
+                                                <FormattedMessage
+                                                    defaultMessage="Not seated"
+                                                    description="Student is not currently seated"
+                                                    id="gui.classroom.teacherDetail.notSeated"
+                                                />
+                                            )}
+                                        </span>
                                         <button
                                             className={styles.deleteButton}
                                             data-member-id={selectedMember}
@@ -1390,6 +1481,11 @@ TeacherClassDetail.propTypes = {
     onCopyInviteLink: PropTypes.func.isRequired,
     onDeleteClassroom: PropTypes.func.isRequired,
     onDeleteMember: PropTypes.func.isRequired,
+    onDownloadAll: PropTypes.func.isRequired,
+    downloadProgress: PropTypes.shape({
+        current: PropTypes.number,
+        total: PropTypes.number,
+    }),
     onOpenSubmission: PropTypes.func.isRequired,
     onRefresh: PropTypes.func.isRequired,
     onReturnSubmission: PropTypes.func.isRequired,
@@ -1613,10 +1709,16 @@ ClassroomModal.propTypes = {
     onCreateClassroom: PropTypes.func.isRequired,
     onDeleteClassroom: PropTypes.func.isRequired,
     onDeleteMember: PropTypes.func.isRequired,
+    onDownloadAll: PropTypes.func.isRequired,
+    downloadProgress: PropTypes.shape({
+        current: PropTypes.number,
+        total: PropTypes.number,
+    }),
     onJoinWithCode: PropTypes.func.isRequired,
     onLeaveClassroom: PropTypes.func.isRequired,
     onOpenSubmission: PropTypes.func.isRequired,
     onRefreshDetail: PropTypes.func.isRequired,
+    onRefreshStudentStatus: PropTypes.func.isRequired,
     onReturnSubmission: PropTypes.func.isRequired,
     onSelectClassroom: PropTypes.func.isRequired,
     onSelectMember: PropTypes.func.isRequired,
@@ -1640,6 +1742,7 @@ ClassroomModal.propTypes = {
         total: PropTypes.number,
         label: PropTypes.string,
     }),
+    teacherComment: PropTypes.string,
     thumbnailDataUrl: PropTypes.string,
 };
 
diff --git a/packages/scratch-gui/src/containers/classroom-modal.jsx b/packages/scratch-gui/src/containers/classroom-modal.jsx
index c6fb74779c2..24eecbc0cb5 100644
--- a/packages/scratch-gui/src/containers/classroom-modal.jsx
+++ b/packages/scratch-gui/src/containers/classroom-modal.jsx
@@ -1,3 +1,4 @@
+import JSZip from 'jszip';
 import React, { useCallback, useState, useEffect, useRef } from 'react';
 import { useIntl } from 'react-intl';
 import { useDispatch, useSelector } from 'react-redux';
@@ -114,6 +115,7 @@ const ClassroomModal = () => {
     // Code display state
     const [codeDisplayClassroom, setCodeDisplayClassroom] = useState(null);
     const [codeDisplayFullscreen, setCodeDisplayFullscreen] = useState(false);
+    const [downloadProgress, setDownloadProgress] = useState(null); // { current, total }
 
     // Refresh timer for teacher detail
     const refreshTimerRef = useRef(null);
@@ -297,7 +299,9 @@ const ClassroomModal = () => {
                         subMap[sub.memberId] = sub;
                     }
                 }
+                const memberIds = new Set();
                 const enrichedMembers = (membersData.members || []).map(m => {
+                    memberIds.add(m.memberId);
                     const sub = subMap[m.memberId];
                     if (sub) {
                         return {
@@ -313,6 +317,24 @@ const ClassroomModal = () => {
                     }
                     return m;
                 });
+                // Add submissions from members who have left
+                for (const [memberId, sub] of Object.entries(subMap)) {
+                    if (!memberIds.has(memberId)) {
+                        enrichedMembers.push({
+                            memberId,
+                            hasSubmission: true,
+                            submissionId: sub.submissionId,
+                            submissionStatus: sub.status || 'submitted',
+                            submittedAt: sub.submittedAt || null,
+                            thumbnailUrl: sub.thumbnailUrl || null,
+                            projectUrl: sub.projectUrl || null,
+                            projectName: sub.projectName || null,
+                            screenshotUrls: sub.screenshotUrls || [],
+                            teacherComment: sub.teacherComment || '',
+                            left: true,
+                        });
+                    }
+                }
                 setSelectedClassroom(classroomData);
                 setMembers(enrichedMembers);
                 return true;
@@ -523,30 +545,54 @@ const ClassroomModal = () => {
         }
     }, [dispatch, pendingJoinCode, selectedSeat, clearError, showError, intl]);
 
-    // --- Student: Verify session on status screen ---
+    // --- Student: Verify session + fetch submission status ---
+
+    const [studentTeacherComment, setStudentTeacherComment] = useState(null);
+
+    const refreshStudentStatus = useCallback(async () => {
+        if (!classroomState.sessionToken) return;
+        setIsLoading(true);
+        try {
+            const result = await classroomAPI.verifySession(classroomState.sessionToken);
+            if (result.submission) {
+                dispatch(setSubmissionStatus(result.submission.status, result.submission.submittedAt));
+                setStudentTeacherComment(result.submission.teacherComment || null);
+            }
+        } catch {
+            dispatch(clearClassroomSession());
+            const title = intl.formatMessage({
+                defaultMessage: 'An error occurred',
+                description: 'Error dialog title',
+                id: 'gui.classroom.error.title',
+            });
+            showError(translateError(intl, { status: 401 }, 'session'), title);
+            setPhase('role-select');
+        } finally {
+            setIsLoading(false);
+        }
+    }, [classroomState.sessionToken, dispatch, showError, intl]);
 
+    // Fetch on student-status phase display
     useEffect(() => {
         if (phase === 'student-status' && classroomState.sessionToken) {
-            classroomAPI.verifySession(classroomState.sessionToken).catch(() => {
-                // Session is invalid — clear and redirect
-                dispatch(clearClassroomSession());
-                const title = intl.formatMessage({
-                    defaultMessage: 'An error occurred',
-                    description: 'Error dialog title',
-                    id: 'gui.classroom.error.title',
-                });
-                showError(translateError(intl, { status: 401 }, 'session'), title);
-                setPhase('role-select');
-            });
+            refreshStudentStatus();
         }
-    }, [phase, classroomState.sessionToken, dispatch, showError, intl]);
+    }, [phase]); // Only on phase change, not on every render
 
     // --- Student: Leave classroom ---
 
-    const handleLeaveClassroom = useCallback(() => {
+    const handleLeaveClassroom = useCallback(async () => {
+        // Notify server to remove member record (best-effort)
+        if (classroomState.sessionToken && classroomState.classroomId) {
+            try {
+                await classroomAPI.leaveClassroom(classroomState.sessionToken, classroomState.classroomId);
+            } catch {
+                // Proceed even if server call fails
+            }
+        }
         dispatch(clearClassroomSession());
         setPhase('role-select');
-    }, [dispatch]);
+    }, [classroomState.sessionToken, classroomState.classroomId, dispatch]);
 
     // --- Student: Start submit flow ---
 
@@ -639,9 +685,23 @@ const ClassroomModal = () => {
                 screenshotBlobs.length,
             );
 
-            // 3. Upload .sb3
+            // 3. Upload .sb3 (with size check)
             setSubmitProgress({ current: 0, total: 1, label: 'project' });
             const sb3Data = await vm.saveProjectSb3();
+            const MAX_FILE_SIZE = 10 * 1024 * 1024; // 10 MB
+            if (sb3Data.byteLength > MAX_FILE_SIZE) {
+                const sizeMB = (sb3Data.byteLength / (1024 * 1024)).toFixed(1);
+                throw new Error(
+                    intl.formatMessage(
+                        {
+                            defaultMessage: 'Project is too large ({size}MB). Maximum size is 10MB.',
+                            description: 'File too large error',
+                            id: 'gui.classroom.error.fileTooLarge',
+                        },
+                        { size: sizeMB },
+                    ),
+                );
+            }
             await classroomAPI.uploadToPresignedUrl(submissionData.uploadUrl, sb3Data, 'application/octet-stream');
 
             // 4. Upload thumbnail
@@ -714,6 +774,76 @@ const ClassroomModal = () => {
         [idToken, selectedClassroom, clearError, showError, intl, loadClassroomDetail],
     );
 
+    // --- Teacher: Download all submissions as ZIP ---
+
+    const handleDownloadAll = useCallback(async () => {
+        if (!selectedClassroom || !members || members.length === 0) return;
+        clearError();
+
+        const submittedMembers = members.filter(m => m.hasSubmission && m.projectUrl);
+        if (submittedMembers.length === 0) return;
+
+        setDownloadProgress({ current: 0, total: submittedMembers.length });
+
+        try {
+            const zip = new JSZip();
+            const className = selectedClassroom.className || 'class';
+
+            for (let i = 0; i < submittedMembers.length; i++) {
+                const m = submittedMembers[i];
+                setDownloadProgress({ current: i + 1, total: submittedMembers.length });
+
+                const seatLabel = m.memberId.replace('seat-', '');
+                const name = m.displayName || '';
+                const folderName = name ? `${seatLabel}_${name}` : seatLabel;
+                const folder = zip.folder(folderName);
+
+                // Download project .sb3
+                try {
+                    const res = await fetch(m.projectUrl);
+                    if (res.ok) folder.file(`${m.projectName || 'project'}.sb3`, await res.blob());
+                } catch {
+                    // Skip failed downloads
+                }
+
+                // Download thumbnail
+                if (m.thumbnailUrl) {
+                    try {
+                        const res = await fetch(m.thumbnailUrl);
+                        if (res.ok) folder.file('thumbnail.png', await res.blob());
+                    } catch {
+                        // Skip
+                    }
+                }
+
+                // Download screenshots
+                for (let si = 0; si < (m.screenshotUrls || []).length; si++) {
+                    try {
+                        const res = await fetch(m.screenshotUrls[si]);
+                        if (res.ok) folder.file(`screenshot-${si}.png`, await res.blob());
+                    } catch {
+                        // Skip
+                    }
+                }
+            }
+
+            // Generate and download ZIP
+            const blob = await zip.generateAsync({ type: 'blob' });
+            const url = URL.createObjectURL(blob);
+            const a = document.createElement('a');
+            a.href = url;
+            a.download = `${className}.zip`;
+            document.body.appendChild(a);
+            a.click();
+            document.body.removeChild(a);
+            URL.revokeObjectURL(url);
+        } catch (err) {
+            showError(translateError(intl, err));
+        } finally {
+            setDownloadProgress(null);
+        }
+    }, [selectedClassroom, members, clearError, showError, intl]);
+
     // --- Classcode URL parameter auto-join ---
     useEffect(() => {
         const urlParams = getUrlParams();
@@ -768,12 +898,16 @@ const ClassroomModal = () => {
             onCreateClassroom={handleCreateClassroom}
             onDeleteClassroom={handleDeleteClassroom}
             onDeleteMember={handleDeleteMember}
+            onDownloadAll={handleDownloadAll}
+            downloadProgress={downloadProgress}
             onJoinWithCode={handleJoinWithCode}
             onLeaveClassroom={handleLeaveClassroom}
             submitProgress={submitProgress}
             onOpenSubmission={handleOpenSubmission}
             onRefreshDetail={handleRefreshDetail}
             onReturnSubmission={handleReturnSubmission}
+            teacherComment={studentTeacherComment}
+            onRefreshStudentStatus={refreshStudentStatus}
             onStartSubmit={handleStartSubmit}
             onConfirmSubmit={handleConfirmSubmit}
             onCancelSubmit={handleCancelSubmit}
diff --git a/packages/scratch-gui/src/lib/classroom-api.js b/packages/scratch-gui/src/lib/classroom-api.js
index f1099f16f67..2af45e874f8 100644
--- a/packages/scratch-gui/src/lib/classroom-api.js
+++ b/packages/scratch-gui/src/lib/classroom-api.js
@@ -121,6 +121,16 @@ class ClassroomAPI {
         return this._request('DELETE', `/classrooms/${classroomId}/members/${memberId}`, null, idToken);
     }
 
+    /**
+     * Leave a classroom (student self-removal).
+     * @param {string} sessionToken - Student session token
+     * @param {string} classroomId - Classroom ID
+     * @returns {Promise<void>}
+     */
+    async leaveClassroom(sessionToken, classroomId) {
+        return this._request('DELETE', `/classrooms/${classroomId}/members/me`, null, sessionToken);
+    }
+
     /**
      * Create a submission (get presigned URLs for upload).
      * @param {string} sessionToken - Student session token
diff --git a/packages/scratch-gui/src/locales/en.js b/packages/scratch-gui/src/locales/en.js
index 5d6bed3b024..afef8a0391b 100644
--- a/packages/scratch-gui/src/locales/en.js
+++ b/packages/scratch-gui/src/locales/en.js
@@ -91,6 +91,12 @@ export default {
     'gui.classroom.teacherDetail.openSubmission': 'Open in Smalruby',
     'gui.classroom.teacherDetail.returnSubmission': 'Return',
     'gui.classroom.teacherDetail.returned': 'Returned',
+    'gui.classroom.teacherDetail.seated': 'Seated',
+    'gui.classroom.teacherDetail.notSeated': 'Not seated',
+    'gui.classroom.teacherDetail.downloadAll': 'Download All',
+    'gui.classroom.error.fileTooLarge': 'Project is too large ({size}MB). Maximum size is 10MB.',
+    'gui.classroom.studentStatus.returned': 'Returned',
+    'gui.classroom.studentStatus.comment': 'Comment',
     'gui.classroom.teacherDetail.cancelDelete': 'Cancel',
     'gui.classroom.codeDisplay.title': 'Class Code',
     'gui.classroom.codeDisplay.copyLink': 'Copy invite link',
diff --git a/packages/scratch-gui/src/locales/ja-Hira.js b/packages/scratch-gui/src/locales/ja-Hira.js
index 749d8ae5577..4846707e684 100644
--- a/packages/scratch-gui/src/locales/ja-Hira.js
+++ b/packages/scratch-gui/src/locales/ja-Hira.js
@@ -88,6 +88,12 @@ export default {
     'gui.classroom.teacherDetail.openSubmission': 'スモウルビーでひらく',
     'gui.classroom.teacherDetail.returnSubmission': 'へんきゃくする',
     'gui.classroom.teacherDetail.returned': 'へんきゃくずみ',
+    'gui.classroom.teacherDetail.seated': 'ちゃくせきちゅう',
+    'gui.classroom.teacherDetail.notSeated': 'りせき',
+    'gui.classroom.teacherDetail.downloadAll': 'ぜんさくひんダウンロード',
+    'gui.classroom.error.fileTooLarge': 'プロジェクトがおおきすぎます（{size}MB）。じょうげんは10MBです。',
+    'gui.classroom.studentStatus.returned': 'へんきゃくずみ',
+    'gui.classroom.studentStatus.comment': 'コメント',
     'gui.classroom.teacherDetail.cancelDelete': 'キャンセル',
     'gui.classroom.codeDisplay.title': 'クラスコード',
     'gui.classroom.codeDisplay.copyLink': 'しょうたいリンクをコピー',
diff --git a/packages/scratch-gui/src/locales/ja.js b/packages/scratch-gui/src/locales/ja.js
index fbec717a33f..b967ed7ad76 100644
--- a/packages/scratch-gui/src/locales/ja.js
+++ b/packages/scratch-gui/src/locales/ja.js
@@ -87,6 +87,12 @@ export default {
     'gui.classroom.teacherDetail.openSubmission': 'スモウルビーで開く',
     'gui.classroom.teacherDetail.returnSubmission': '返却する',
     'gui.classroom.teacherDetail.returned': '返却済み',
+    'gui.classroom.teacherDetail.seated': '着席中',
+    'gui.classroom.teacherDetail.notSeated': '離席',
+    'gui.classroom.teacherDetail.downloadAll': '全作品ダウンロード',
+    'gui.classroom.error.fileTooLarge': 'プロジェクトが大きすぎます（{size}MB）。上限は10MBです。',
+    'gui.classroom.studentStatus.returned': '返却済み',
+    'gui.classroom.studentStatus.comment': 'コメント',
     'gui.classroom.teacherDetail.cancelDelete': 'キャンセル',
     'gui.classroom.codeDisplay.title': 'クラスコード',
     'gui.classroom.codeDisplay.copyLink': '招待リンクをコピー',