feat: implement group creation and management (US #28)

Backend:
- Add groups Django app with models: Group, GroupMember, GroupInvite, JoinRequest
- Create serializers with business rule validation
- Implement GroupViewSet with full CRUD + custom actions (members, invites, roles, leave, join requests)
- Add JoinGroupViewSet for invite-based joining flow
- Register app in Django config and URL routing

Frontend:
- Add shared types for groups to @cloud-reader/shared
- Create groups API client (groupsApi)
- Build GroupsListPage, GroupDetailPage (member mgmt, invites, role transfer)
- Build CreateGroupPage and JoinGroupPage
- Add lazy-loaded routes to App.tsx with ProtectedRoute
- Add navigation links to Library header

Ref: #28

backend/apps/groups/admin.py

@@ -1,38 +1,30 @@
 from django.contrib import admin
 
-from apps.groups.models import (
-    GroupMeeting,
-    GroupMembership,
-    NotificationPreference,
-    PaceNotification,
-    ReadingGroup,
-)
+from apps.groups.models import Group, GroupInvite, GroupMember, JoinRequest
 
 
-@admin.register(ReadingGroup)
-class ReadingGroupAdmin(admin.ModelAdmin):
-    list_display = ["name", "created_by", "created_at"]
-    search_fields = ["name"]
+@admin.register(Group)
+class GroupAdmin(admin.ModelAdmin):
+    list_display = ["id", "name", "created_by", "created_at"]
+    search_fields = ["name", "created_by__email"]
 
 
-@admin.register(GroupMembership)
-class GroupMembershipAdmin(admin.ModelAdmin):
-    list_display = ["user", "group", "role", "joined_at"]
+@admin.register(GroupMember)
+class GroupMemberAdmin(admin.ModelAdmin):
+    list_display = ["id", "group", "user", "role", "joined_at"]
     list_filter = ["role"]
+    search_fields = ["group__name", "user__email"]
 
 
-@admin.register(GroupMeeting)
-class GroupMeetingAdmin(admin.ModelAdmin):
-    list_display = ["group", "title", "target_section_label", "scheduled_at"]
-    list_filter = ["group"]
+@admin.register(GroupInvite)
+class GroupInviteAdmin(admin.ModelAdmin):
+    list_display = ["id", "group", "code", "created_by", "use_count", "is_active", "created_at"]
+    list_filter = ["is_active"]
+    search_fields = ["code", "group__name"]
 
 
-@admin.register(NotificationPreference)
-class NotificationPreferenceAdmin(admin.ModelAdmin):
-    list_display = ["user", "pace_notifications_enabled", "reminder_enabled", "frequency"]
-
-
-@admin.register(PaceNotification)
-class PaceNotificationAdmin(admin.ModelAdmin):
-    list_display = ["user", "meeting", "status", "created_at"]
+@admin.register(JoinRequest)
+class JoinRequestAdmin(admin.ModelAdmin):
+    list_display = ["id", "group", "user", "status", "created_at"]
     list_filter = ["status"]
+    search_fields = ["group__name", "user__email"]

backend/apps/groups/apps.py

@@ -4,5 +4,4 @@ from django.apps import AppConfig
 class GroupsConfig(AppConfig):
     default_auto_field = "django.db.models.BigAutoField"
     name = "apps.groups"
-    verbose_name = "Reading Groups"
-    label = "groups"
+    verbose_name = "Groups"

backend/apps/groups/migrations/0001_initial.py

@@ -1,109 +1,88 @@
-# Generated by Django 5.1.7 on 2026-06-20 19:22
+# Generated by Django 5.x for groups app
 
-import django.db.models.deletion
 from django.conf import settings
 from django.db import migrations, models
+import django.db.models.deletion
+import uuid
 
 
 class Migration(migrations.Migration):
-
     initial = True
 
     dependencies = [
-        ('books', '0003_readingprogress_epub_location'),
-        ('users', '0001_initial'),
         migrations.swappable_dependency(settings.AUTH_USER_MODEL),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='NotificationPreference',
+            name="Group",
             fields=[
-                ('user', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, primary_key=True, related_name='notification_preference', serialize=False, to=settings.AUTH_USER_MODEL)),
-                ('pace_notifications_enabled', models.BooleanField(default=True)),
-                ('reminder_enabled', models.BooleanField(default=True)),
-                ('frequency', models.CharField(choices=[('daily', 'Daily'), ('weekly', 'Weekly')], default='daily', max_length=16)),
-                ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('updated_at', models.DateTimeField(auto_now=True)),
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("name", models.CharField(db_index=True, max_length=256)),
+                ("description", models.TextField(blank=True, default="")),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                ("updated_at", models.DateTimeField(auto_now=True)),
+                ("created_by", models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name="created_groups", to=settings.AUTH_USER_MODEL)),
             ],
             options={
-                'verbose_name': 'Notification Preference',
-                'verbose_name_plural': 'Notification Preferences',
-                'db_table': 'groups_notification_preference',
+                "db_table": "groups_group",
+                "verbose_name": "Group",
+                "verbose_name_plural": "Groups",
+                "ordering": ["-created_at"],
             },
         ),
         migrations.CreateModel(
-            name='ReadingGroup',
+            name="GroupMember",
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('name', models.CharField(db_index=True, max_length=256)),
-                ('description', models.TextField(blank=True, default='')),
-                ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('book', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='reading_groups', to='books.book')),
-                ('created_by', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='created_groups', to=settings.AUTH_USER_MODEL)),
-                ('ebook', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='reading_groups', to='books.ebook')),
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("role", models.CharField(choices=[("admin", "Admin"), ("member", "Member")], default="member", max_length=16)),
+                ("joined_at", models.DateTimeField(auto_now_add=True)),
+                ("group", models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name="memberships", to="groups.group")),
+                ("user", models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name="group_memberships", to=settings.AUTH_USER_MODEL)),
             ],
             options={
-                'verbose_name': 'Reading Group',
-                'verbose_name_plural': 'Reading Groups',
-                'db_table': 'groups_reading_group',
-                'ordering': ['-created_at'],
+                "db_table": "groups_member",
+                "verbose_name": "Group Member",
+                "verbose_name_plural": "Group Members",
+                "ordering": ["joined_at"],
+                "unique_together": {("group", "user")},
             },
         ),
         migrations.CreateModel(
-            name='GroupMeeting',
+            name="GroupInvite",
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('title', models.CharField(blank=True, default='', max_length=512)),
-                ('scheduled_at', models.DateTimeField(db_index=True)),
-                ('target_section', models.PositiveIntegerField(default=0, help_text='Target chapter/section index to reach by this meeting')),
-                ('target_section_label', models.CharField(blank=True, default='', help_text="Human-readable label for the target section (e.g. 'Section 3')", max_length=512)),
-                ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('group', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='meetings', to='groups.readinggroup')),
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("code", models.UUIDField(db_index=True, default=uuid.uuid4, editable=False, unique=True)),
+                ("max_uses", models.PositiveIntegerField(default=0, help_text="0 = unlimited")),
+                ("use_count", models.PositiveIntegerField(default=0)),
+                ("is_active", models.BooleanField(db_index=True, default=True)),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                ("created_by", models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name="created_invites", to=settings.AUTH_USER_MODEL)),
+                ("group", models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name="invites", to="groups.group")),
             ],
             options={
-                'verbose_name': 'Group Meeting',
-                'verbose_name_plural': 'Group Meetings',
-                'db_table': 'groups_meeting',
-                'ordering': ['scheduled_at'],
+                "db_table": "groups_invite",
+                "verbose_name": "Group Invite",
+                "verbose_name_plural": "Group Invites",
+                "ordering": ["-created_at"],
             },
         ),
         migrations.CreateModel(
-            name='PaceNotification',
+            name="JoinRequest",
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('status', models.CharField(choices=[('pending', 'Pending'), ('sent', 'Sent'), ('dismissed', 'Dismissed')], default='pending', max_length=16)),
-                ('current_section', models.PositiveIntegerField(default=0)),
-                ('target_section', models.PositiveIntegerField(default=0)),
-                ('ahead_behind_delta', models.IntegerField(default=0)),
-                ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('ebook', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='pace_notifications', to='books.ebook')),
-                ('meeting', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='pace_notifications', to='groups.groupmeeting')),
-                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='pace_notifications', to=settings.AUTH_USER_MODEL)),
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("status", models.CharField(choices=[("pending", "Pending"), ("approved", "Approved"), ("rejected", "Rejected")], db_index=True, default="pending", max_length=16)),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                ("group", models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name="join_requests", to="groups.group")),
+                ("invite", models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name="join_requests", to="groups.groupinvite")),
+                ("user", models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name="join_requests", to=settings.AUTH_USER_MODEL)),
             ],
             options={
-                'verbose_name': 'Pace Notification',
-                'verbose_name_plural': 'Pace Notifications',
-                'db_table': 'groups_pace_notification',
-                'ordering': ['-created_at'],
-                'indexes': [models.Index(fields=['user', 'meeting', 'ebook'], name='groups_pace_user_id_18e929_idx')],
-            },
-        ),
-        migrations.CreateModel(
-            name='GroupMembership',
-            fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('role', models.CharField(choices=[('admin', 'Admin'), ('member', 'Member')], default='member', max_length=16)),
-                ('joined_at', models.DateTimeField(auto_now_add=True)),
-                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='group_memberships', to=settings.AUTH_USER_MODEL)),
-                ('group', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='memberships', to='groups.readinggroup')),
-            ],
-            options={
-                'verbose_name': 'Group Membership',
-                'verbose_name_plural': 'Group Memberships',
-                'db_table': 'groups_membership',
-                'indexes': [models.Index(fields=['user', 'group'], name='groups_memb_user_id_9cda7e_idx')],
-                'unique_together': {('user', 'group')},
+                "db_table": "groups_join_request",
+                "verbose_name": "Join Request",
+                "verbose_name_plural": "Join Requests",
+                "ordering": ["-created_at"],
+                "unique_together": {("group", "user")},
             },
         ),
     ]

backend/apps/groups/models.py

@@ -1,190 +1,129 @@
-from __future__ import annotations
+import uuid
 
 from django.conf import settings
 from django.db import models
 
 
-class FrequencyChoice(models.TextChoices):
-    DAILY = "daily", "Daily"
-    WEEKLY = "weekly", "Weekly"
-
-
-class MembershipRole(models.TextChoices):
+class GroupRole(models.TextChoices):
     ADMIN = "admin", "Admin"
     MEMBER = "member", "Member"
 
 
-class NotificationStatus(models.TextChoices):
+class JoinRequestStatus(models.TextChoices):
     PENDING = "pending", "Pending"
-    SENT = "sent", "Sent"
-    DISMISSED = "dismissed", "Dismissed"
+    APPROVED = "approved", "Approved"
+    REJECTED = "rejected", "Rejected"
 
 
-class ReadingGroup(models.Model):
-    """A group of users reading a book together with scheduled meetings."""
-
+class Group(models.Model):
     name = models.CharField(max_length=256, db_index=True)
     description = models.TextField(blank=True, default="")
-    book = models.ForeignKey(
-        "books.Book",
-        on_delete=models.SET_NULL,
-        null=True,
-        blank=True,
-        related_name="reading_groups",
-    )
-    ebook = models.ForeignKey(
-        "books.EBook",
-        on_delete=models.SET_NULL,
-        null=True,
-        blank=True,
-        related_name="reading_groups",
-    )
     created_by = models.ForeignKey(
         settings.AUTH_USER_MODEL,
         on_delete=models.CASCADE,
         related_name="created_groups",
     )
     created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
 
     class Meta:
-        db_table = "groups_reading_group"
-        verbose_name = "Reading Group"
-        verbose_name_plural = "Reading Groups"
+        db_table = "groups_group"
+        verbose_name = "Group"
+        verbose_name_plural = "Groups"
         ordering = ["-created_at"]
 
     def __str__(self) -> str:
         return self.name
 
 
-class GroupMembership(models.Model):
-    """User membership in a reading group."""
-
+class GroupMember(models.Model):
+    group = models.ForeignKey(
+        Group,
+        on_delete=models.CASCADE,
+        related_name="memberships",
+    )
     user = models.ForeignKey(
         settings.AUTH_USER_MODEL,
         on_delete=models.CASCADE,
         related_name="group_memberships",
     )
-    group = models.ForeignKey(
-        ReadingGroup,
-        on_delete=models.CASCADE,
-        related_name="memberships",
-    )
     role = models.CharField(
         max_length=16,
-        choices=MembershipRole.choices,
-        default=MembershipRole.MEMBER,
+        choices=GroupRole.choices,
+        default=GroupRole.MEMBER,
     )
     joined_at = models.DateTimeField(auto_now_add=True)
 
     class Meta:
-        db_table = "groups_membership"
-        verbose_name = "Group Membership"
-        verbose_name_plural = "Group Memberships"
-        unique_together = [("user", "group")]
-        indexes = [models.Index(fields=["user", "group"])]
+        db_table = "groups_member"
+        verbose_name = "Group Member"
+        verbose_name_plural = "Group Members"
+        ordering = ["joined_at"]
+        unique_together = [("group", "user")]
 
     def __str__(self) -> str:
-        return f"{self.user} in {self.group}"
+        return f"{self.user} in {self.group} ({self.role})"
 
 
-class GroupMeeting(models.Model):
-    """A scheduled meeting for a reading group with a target section."""
-
+class GroupInvite(models.Model):
     group = models.ForeignKey(
-        ReadingGroup,
+        Group,
         on_delete=models.CASCADE,
-        related_name="meetings",
+        related_name="invites",
     )
-    title = models.CharField(max_length=512, blank=True, default="")
-    scheduled_at = models.DateTimeField(db_index=True)
-    target_section = models.PositiveIntegerField(
-        default=0,
-        help_text="Target chapter/section index to reach by this meeting",
-    )
-    target_section_label = models.CharField(
-        max_length=512,
-        blank=True,
-        default="",
-        help_text="Human-readable label for the target section (e.g. 'Section 3')",
-    )
-    created_at = models.DateTimeField(auto_now_add=True)
-
-    class Meta:
-        db_table = "groups_meeting"
-        verbose_name = "Group Meeting"
-        verbose_name_plural = "Group Meetings"
-        ordering = ["scheduled_at"]
-
-    def __str__(self) -> str:
-        return f"{self.group.name} — {self.title or self.target_section_label} ({self.scheduled_at.date()})"
-
-
-class NotificationPreference(models.Model):
-    """Per-user notification settings for reading pace alerts."""
-
-    user = models.OneToOneField(
+    created_by = models.ForeignKey(
         settings.AUTH_USER_MODEL,
         on_delete=models.CASCADE,
-        related_name="notification_preference",
-        primary_key=True,
-    )
-    pace_notifications_enabled = models.BooleanField(default=True)
-    reminder_enabled = models.BooleanField(default=True)
-    frequency = models.CharField(
-        max_length=16,
-        choices=FrequencyChoice.choices,
-        default=FrequencyChoice.DAILY,
+        related_name="created_invites",
     )
+    code = models.UUIDField(default=uuid.uuid4, unique=True, editable=False, db_index=True)
+    max_uses = models.PositiveIntegerField(default=0, help_text="0 = unlimited")
+    use_count = models.PositiveIntegerField(default=0)
+    is_active = models.BooleanField(default=True, db_index=True)
     created_at = models.DateTimeField(auto_now_add=True)
-    updated_at = models.DateTimeField(auto_now=True)
 
     class Meta:
-        db_table = "groups_notification_preference"
-        verbose_name = "Notification Preference"
-        verbose_name_plural = "Notification Preferences"
+        db_table = "groups_invite"
+        verbose_name = "Group Invite"
+        verbose_name_plural = "Group Invites"
+        ordering = ["-created_at"]
 
     def __str__(self) -> str:
-        return f"{self.user} — pace={'on' if self.pace_notifications_enabled else 'off'}, freq={self.frequency}"
+        return f"Invite for {self.group.name} ({self.code})"
 
 
-class PaceNotification(models.Model):
-    """Tracks reading pace notifications sent to users to avoid duplicates."""
-
+class JoinRequest(models.Model):
+    group = models.ForeignKey(
+        Group,
+        on_delete=models.CASCADE,
+        related_name="join_requests",
+    )
     user = models.ForeignKey(
         settings.AUTH_USER_MODEL,
         on_delete=models.CASCADE,
-        related_name="pace_notifications",
+        related_name="join_requests",
     )
-    meeting = models.ForeignKey(
-        GroupMeeting,
-        on_delete=models.CASCADE,
-        related_name="pace_notifications",
-    )
-    ebook = models.ForeignKey(
-        "books.EBook",
-        on_delete=models.CASCADE,
-        related_name="pace_notifications",
+    invite = models.ForeignKey(
+        GroupInvite,
+        on_delete=models.SET_NULL,
         null=True,
         blank=True,
+        related_name="join_requests",
     )
     status = models.CharField(
         max_length=16,
-        choices=NotificationStatus.choices,
-        default=NotificationStatus.PENDING,
+        choices=JoinRequestStatus.choices,
+        default=JoinRequestStatus.PENDING,
+        db_index=True,
     )
-    current_section = models.PositiveIntegerField(default=0)
-    target_section = models.PositiveIntegerField(default=0)
-    ahead_behind_delta = models.IntegerField(default=0)
     created_at = models.DateTimeField(auto_now_add=True)
 
     class Meta:
-        db_table = "groups_pace_notification"
-        verbose_name = "Pace Notification"
-        verbose_name_plural = "Pace Notifications"
+        db_table = "groups_join_request"
+        verbose_name = "Join Request"
+        verbose_name_plural = "Join Requests"
         ordering = ["-created_at"]
-        indexes = [
-            models.Index(fields=["user", "meeting", "ebook"]),
-        ]
+        unique_together = [("group", "user")]
 
     def __str__(self) -> str:
-        return f"{self.user} — meeting {self.meeting_id}: {self.get_status_display()}"
+        return f"{self.user} → {self.group.name} ({self.status})"

backend/apps/groups/permissions.py

@@ -0,0 +1,25 @@
+from rest_framework import permissions
+from rest_framework.request import Request
+
+from apps.groups.models import Group, GroupMember, GroupRole
+
+
+class IsGroupAdmin(permissions.BasePermission):
+    """Only group admins can perform the action."""
+
+    def has_object_permission(self, request: Request, view: object, obj: Group) -> bool:
+        return GroupMember.objects.filter(
+            group=obj,
+            user=request.user,
+            role=GroupRole.ADMIN,
+        ).exists()
+
+
+class IsGroupMember(permissions.BasePermission):
+    """Only group members (any role) can perform the action."""
+
+    def has_object_permission(self, request: Request, view: object, obj: Group) -> bool:
+        return GroupMember.objects.filter(
+            group=obj,
+            user=request.user,
+        ).exists()

backend/apps/groups/serializers.py

@@ -2,136 +2,197 @@ from __future__ import annotations
 
 from rest_framework import serializers
 
-from apps.groups.models import (
-    FrequencyChoice,
-    GroupMeeting,
-    GroupMembership,
-    NotificationPreference,
-    PaceNotification,
-    ReadingGroup,
-)
-from apps.groups.services.pace import PaceStatus
+from apps.groups.models import Group, GroupInvite, GroupMember, GroupRole, JoinRequest, JoinRequestStatus
 
 
-class NotificationPreferenceSerializer(serializers.ModelSerializer):
-    class Meta:
-        model = NotificationPreference
-        fields = [
-            "pace_notifications_enabled",
-            "reminder_enabled",
-            "frequency",
-        ]
-
-    def validate_frequency(self, value: str) -> str:
-        valid = {choice[0] for choice in FrequencyChoice.choices}
-        if value not in valid:
-            raise serializers.ValidationError(
-                f"Frequency must be one of: {', '.join(valid)}"
-            )
-        return value
-
-
-class GroupMeetingSerializer(serializers.ModelSerializer):
-    group_name = serializers.CharField(source="group.name", read_only=True)
-
-    class Meta:
-        model = GroupMeeting
-        fields = [
-            "id",
-            "group",
-            "group_name",
-            "title",
-            "scheduled_at",
-            "target_section",
-            "target_section_label",
-            "created_at",
-        ]
-        read_only_fields = ["id", "created_at"]
-
-    def validate_target_section(self, value: int) -> int:
-        if value < 0:
-            raise serializers.ValidationError("Target section must be non-negative.")
-        return value
-
-
-class ReadingGroupSerializer(serializers.ModelSerializer):
-    member_count = serializers.SerializerMethodField()
-    meeting_count = serializers.SerializerMethodField()
-
-    class Meta:
-        model = ReadingGroup
-        fields = [
-            "id",
-            "name",
-            "description",
-            "book",
-            "ebook",
-            "created_by",
-            "created_at",
-            "member_count",
-            "meeting_count",
-        ]
-        read_only_fields = ["id", "created_by", "created_at"]
-
-    def get_member_count(self, obj: ReadingGroup) -> int:
-        return obj.memberships.count()
-
-    def get_meeting_count(self, obj: ReadingGroup) -> int:
-        return obj.meetings.count()
-
-
-class GroupMembershipSerializer(serializers.ModelSerializer):
+class GroupMemberSerializer(serializers.ModelSerializer):
+    user_id = serializers.IntegerField(source="user.id", read_only=True)
     user_email = serializers.CharField(source="user.email", read_only=True)
-    group_name = serializers.CharField(source="group.name", read_only=True)
+    user_username = serializers.CharField(source="user.username", read_only=True)
 
     class Meta:
-        model = GroupMembership
-        fields = ["id", "user", "user_email", "group", "group_name", "role", "joined_at"]
-        read_only_fields = ["id", "joined_at"]
-
-
-class PaceNotificationSerializer(serializers.ModelSerializer):
-    status_display = serializers.CharField(source="get_status_display", read_only=True)
-
-    class Meta:
-        model = PaceNotification
+        model = GroupMember
         fields = [
-            "id",
-            "user",
-            "meeting",
-            "ebook",
-            "status",
-            "status_display",
-            "current_section",
-            "target_section",
-            "ahead_behind_delta",
-            "created_at",
+            "id", "user_id", "user_email", "user_username",
+            "role", "joined_at",
         ]
-        read_only_fields = ["id", "created_at"]
 
 
-class PaceStatusSerializer(serializers.Serializer):
-    meeting_id = serializers.IntegerField()
-    meeting_title = serializers.CharField()
-    scheduled_at = serializers.CharField()
-    target_section = serializers.IntegerField()
-    target_section_label = serializers.CharField()
-    current_section = serializers.IntegerField()
-    ahead_behind_delta = serializers.IntegerField()
-    status = serializers.CharField()
-    days_until_meeting = serializers.IntegerField()
-    sections_to_catch_up = serializers.IntegerField()
-    ebook_id = serializers.IntegerField()
-    ebook_title = serializers.CharField()
+class GroupListSerializer(serializers.ModelSerializer):
+    member_count = serializers.SerializerMethodField()
+    user_role = serializers.SerializerMethodField()
+
+    class Meta:
+        model = Group
+        fields = [
+            "id", "name", "description", "created_by",
+            "member_count", "user_role", "created_at", "updated_at",
+        ]
+
+    def get_member_count(self, obj: Group) -> int:
+        return getattr(obj, "_member_count", obj.memberships.count())
+
+    def get_user_role(self, obj: Group) -> str | None:
+        request = self.context.get("request")
+        if not request or not request.user.is_authenticated:
+            return None
+        membership = getattr(obj, "_user_membership", None)
+        if membership is None:
+            try:
+                membership = obj.memberships.get(user=request.user)
+            except GroupMember.DoesNotExist:
+                return None
+        return membership.role
 
 
-class ReminderSerializer(serializers.Serializer):
-    meeting_id = serializers.IntegerField()
-    meeting_title = serializers.CharField()
-    scheduled_at = serializers.CharField()
-    target_section = serializers.IntegerField()
-    target_section_label = serializers.CharField()
-    group_name = serializers.CharField()
-    hours_until = serializers.IntegerField()
-    ebook_id = serializers.IntegerField()
-    ebook_title = serializers.CharField()
+class GroupDetailSerializer(serializers.ModelSerializer):
+    members = GroupMemberSerializer(source="memberships", many=True, read_only=True)
+    member_count = serializers.SerializerMethodField()
+    user_role = serializers.SerializerMethodField()
+    created_by_email = serializers.CharField(source="created_by.email", read_only=True)
+    created_by_username = serializers.CharField(source="created_by.username", read_only=True)
+
+    class Meta:
+        model = Group
+        fields = [
+            "id", "name", "description", "created_by", "created_by_email",
+            "created_by_username", "members", "member_count", "user_role",
+            "created_at", "updated_at",
+        ]
+
+    def get_member_count(self, obj: Group) -> int:
+        return getattr(obj, "_member_count", obj.memberships.count())
+
+    def get_user_role(self, obj: Group) -> str | None:
+        request = self.context.get("request")
+        if not request or not request.user.is_authenticated:
+            return None
+        membership = getattr(obj, "_user_membership", None)
+        if membership is None:
+            try:
+                membership = obj.memberships.get(user=request.user)
+            except GroupMember.DoesNotExist:
+                return None
+        return membership.role
+
+
+class GroupCreateSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Group
+        fields = ["name", "description"]
+
+    def validate_name(self, value: str) -> str:
+        if not value.strip():
+            raise serializers.ValidationError("Group name cannot be empty.")
+        if len(value.strip()) < 2:
+            raise serializers.ValidationError("Group name must be at least 2 characters.")
+        return value.strip()
+
+    def create(self, validated_data: dict) -> Group:
+        user = self.context["request"].user
+        group = Group.objects.create(created_by=user, **validated_data)
+        GroupMember.objects.create(group=group, user=user, role=GroupRole.ADMIN)
+        return group
+
+
+class GroupUpdateSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Group
+        fields = ["name", "description"]
+
+    def validate_name(self, value: str) -> str:
+        if not value.strip():
+            raise serializers.ValidationError("Group name cannot be empty.")
+        if len(value.strip()) < 2:
+            raise serializers.ValidationError("Group name must be at least 2 characters.")
+        return value.strip()
+
+
+class GroupInviteSerializer(serializers.ModelSerializer):
+    created_by_email = serializers.CharField(source="created_by.email", read_only=True)
+    group_name = serializers.CharField(source="group.name", read_only=True)
+    join_url = serializers.SerializerMethodField()
+
+    class Meta:
+        model = GroupInvite
+        fields = [
+            "id", "group", "group_name", "code", "created_by", "created_by_email",
+            "max_uses", "use_count", "is_active", "join_url", "created_at",
+        ]
+        read_only_fields = ["id", "group", "code", "created_by", "use_count", "created_at"]
+
+    def get_join_url(self, obj: GroupInvite) -> str:
+        request = self.context.get("request")
+        if request:
+            return f"{request.build_absolute_uri('/')[:-1]}/groups/join/{obj.code}"
+        return f"/groups/join/{obj.code}"
+
+
+class GroupInviteCreateSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = GroupInvite
+        fields = ["max_uses"]
+
+    def validate_max_uses(self, value: int) -> int:
+        if value < 0:
+            raise serializers.ValidationError("Max uses cannot be negative.")
+        return value
+
+    def create(self, validated_data: dict) -> GroupInvite:
+        group = self.context["group"]
+        user = self.context["request"].user
+        return GroupInvite.objects.create(
+            group=group,
+            created_by=user,
+            **validated_data,
+        )
+
+
+class JoinRequestSerializer(serializers.ModelSerializer):
+    user_id = serializers.IntegerField(source="user.id", read_only=True)
+    user_email = serializers.CharField(source="user.email", read_only=True)
+    user_username = serializers.CharField(source="user.username", read_only=True)
+    group_name = serializers.CharField(source="group.name", read_only=True)
+    invite_code = serializers.UUIDField(source="invite.code", read_only=True, default=None)
+
+    class Meta:
+        model = JoinRequest
+        fields = [
+            "id", "group", "group_name", "user", "user_id", "user_email",
+            "user_username", "invite", "invite_code", "status", "created_at",
+        ]
+        read_only_fields = ["id", "group", "user", "invite", "created_at"]
+
+
+class JoinViaInviteSerializer(serializers.Serializer):
+    """Validates and processes joining a group via an invite code."""
+
+    code = serializers.UUIDField()
+
+    def validate_code(self, value: str) -> str:
+        try:
+            invite = GroupInvite.objects.select_related("group").get(code=value)
+        except GroupInvite.DoesNotExist:
+            raise serializers.ValidationError("Invalid invite code.")
+
+        if not invite.is_active:
+            raise serializers.ValidationError("This invite is no longer active.")
+
+        if invite.max_uses > 0 and invite.use_count >= invite.max_uses:
+            raise serializers.ValidationError("This invite has reached its maximum uses.")
+
+        return value
+
+
+class RoleUpdateSerializer(serializers.Serializer):
+    role = serializers.ChoiceField(choices=GroupRole.choices)
+
+    def validate_role(self, value: str) -> str:
+        if value == GroupRole.MEMBER:
+            group = self.context["group"]
+            admin_count = group.memberships.filter(role=GroupRole.ADMIN).count()
+            if admin_count <= 1:
+                raise serializers.ValidationError(
+                    "Cannot remove the last admin. Transfer admin role first or dissolve the group."
+                )
+        return value

backend/apps/groups/services/pace.py

@@ -1,219 +0,0 @@
-"""Pace calculation service for reading progress vs meeting targets."""
-
-from __future__ import annotations
-
-import logging
-from datetime import datetime, timedelta
-from typing import TypedDict
-
-from django.db.models import QuerySet
-from django.utils import timezone
-
-from apps.books.models import EBook, ReadingProgress
-from apps.groups.models import (
-    GroupMeeting,
-    GroupMembership,
-    NotificationPreference,
-    PaceNotification,
-    NotificationStatus,
-)
-
-logger = logging.getLogger(__name__)
-
-
-class PaceStatus(TypedDict):
-    meeting_id: int
-    meeting_title: str
-    scheduled_at: str
-    target_section: int
-    target_section_label: str
-    current_section: int
-    ahead_behind_delta: int
-    status: str  # "ahead", "behind", "on_track", "completed"
-    days_until_meeting: int
-    sections_to_catch_up: int
-    ebook_id: int
-    ebook_title: str
-
-
-def get_relevant_ebooks_for_user(user) -> QuerySet[EBook]:
-    """Return ebooks that belong to groups the user is a member of."""
-    group_ids = (
-        GroupMembership.objects.filter(user=user)
-        .values_list("group_id", flat=True)
-    )
-    return (
-        EBook.objects.filter(reading_groups__in=group_ids)
-        .select_related("reading_progress")
-        .prefetch_related("chapters")
-        .distinct()
-    )
-
-
-def calculate_pace(
-    user,
-    ebook: EBook | None = None,
-    meeting: GroupMeeting | None = None,
-) -> list[PaceStatus]:
-    """Calculate reading pace for a user's upcoming meetings.
-
-    Compares the user's current reading progress (chapter index) against
-    the target section for each upcoming meeting within 3 days.
-    """
-    now = timezone.now()
-    three_days_from_now = now + timedelta(days=3)
-
-    # Find upcoming meetings for groups the user belongs to
-    user_group_ids = (
-        GroupMembership.objects.filter(user=user)
-        .values_list("group_id", flat=True)
-    )
-    meetings_qs = GroupMeeting.objects.filter(
-        group_id__in=user_group_ids,
-        scheduled_at__gte=now,
-        scheduled_at__lte=three_days_from_now,
-    ).select_related("group", "group__ebook")
-
-    if meeting:
-        meetings_qs = meetings_qs.filter(pk=meeting.pk)
-
-    meetings = list(meetings_qs)
-
-    results: list[PaceStatus] = []
-
-    for m in meetings:
-        group_ebook = m.group.ebook
-        ebooks_to_check: list[EBook] = []
-
-        if ebook:
-            ebooks_to_check = [ebook]
-        elif group_ebook:
-            ebooks_to_check = [group_ebook]
-        else:
-            # Check all ebooks in the group
-            ebooks_to_check = list(
-                EBook.objects.filter(reading_groups=m.group)
-                .select_related("reading_progress")
-                .prefetch_related("chapters")
-            )
-
-        for eb in ebooks_to_check:
-            pace = _compute_single_pace(user, m, eb, now)
-            if pace:
-                results.append(pace)
-
-    return results
-
-
-def _compute_single_pace(
-    user,
-    meeting: GroupMeeting,
-    ebook: EBook,
-    now: datetime,
-) -> PaceStatus | None:
-    """Compute pace for one user + meeting + ebook combination."""
-    try:
-        progress = ebook.reading_progress
-    except ReadingProgress.DoesNotExist:
-        # No progress yet — user hasn't started reading
-        return None
-
-    # Current section: based on last_page (chapter index) or computed from progress %
-    if progress.last_page > 0:
-        current_section = progress.last_page
-    elif progress.current_position > 0:
-        chapter_count = ebook.chapters.count() or ebook.page_count or 1
-        current_section = max(1, int((progress.current_position / 100) * chapter_count))
-    else:
-        current_section = 0
-
-    target_section = meeting.target_section or 0
-    if target_section == 0:
-        return None
-
-    delta = current_section - target_section
-    days_until = max(0, (meeting.scheduled_at - now).days)
-
-    if current_section >= target_section:
-        if current_section >= target_section and progress.current_position > 0:
-            status = "completed"
-        else:
-            status = "ahead"
-    elif delta >= -1:
-        status = "on_track"
-    else:
-        status = "behind"
-
-    return PaceStatus(
-        meeting_id=meeting.pk,
-        meeting_title=meeting.title or meeting.target_section_label,
-        scheduled_at=meeting.scheduled_at.isoformat(),
-        target_section=target_section,
-        target_section_label=meeting.target_section_label,
-        current_section=current_section,
-        ahead_behind_delta=delta,
-        status=status,
-        days_until_meeting=days_until,
-        sections_to_catch_up=max(0, target_section - current_section),
-        ebook_id=ebook.pk,
-        ebook_title=ebook.title,
-    )
-
-
-def should_send_notification(
-    user,
-    meeting: GroupMeeting,
-    ebook: EBook,
-) -> bool:
-    """Check if a pace notification should be sent based on user preferences."""
-    pref, _ = NotificationPreference.objects.get_or_create(user=user)
-
-    if not pref.pace_notifications_enabled:
-        return False
-
-    # Check if notification was already sent today
-    today = timezone.now().date()
-    existing = PaceNotification.objects.filter(
-        user=user,
-        meeting=meeting,
-        ebook=ebook,
-        created_at__date=today,
-    ).exclude(status=NotificationStatus.DISMISSED)
-
-    if existing.exists():
-        return False
-
-    # Frequency check
-    if pref.frequency == "weekly":
-        week_ago = today - timedelta(days=7)
-        recent = PaceNotification.objects.filter(
-            user=user,
-            meeting=meeting,
-            ebook=ebook,
-            created_at__date__gte=week_ago,
-        ).exclude(status=NotificationStatus.DISMISSED)
-        if recent.exists():
-            return False
-
-    return True
-
-
-def get_reminder_meetings(user) -> list[GroupMeeting]:
-    """Get meetings that are within 24 hours for reminder notifications."""
-    now = timezone.now()
-    tomorrow = now + timedelta(days=1)
-
-    user_group_ids = (
-        GroupMembership.objects.filter(user=user)
-        .values_list("group_id", flat=True)
-    )
-
-    return list(
-        GroupMeeting.objects.filter(
-            group_id__in=user_group_ids,
-            scheduled_at__gte=now,
-            scheduled_at__lte=tomorrow,
-        )
-        .select_related("group", "group__ebook")
-        .order_by("scheduled_at")
-    )

backend/apps/groups/urls.py

@@ -1,23 +1,12 @@
 from django.urls import include, path
 from rest_framework.routers import DefaultRouter
 
-from apps.groups.views import (
-    GroupMeetingViewSet,
-    ReadingGroupViewSet,
-    dismiss_pace_notification_view,
-    notification_preferences_view,
-    pace_status_view,
-    reminder_view,
-)
+from apps.groups.views import GroupViewSet, JoinGroupViewSet
 
 router = DefaultRouter()
-router.register(r"groups", ReadingGroupViewSet, basename="reading-group")
-router.register(r"meetings", GroupMeetingViewSet, basename="group-meeting")
+router.register(r"groups", GroupViewSet, basename="group")
+router.register(r"join", JoinGroupViewSet, basename="join-group")
 
 urlpatterns = [
     path("", include(router.urls)),
-    path("notifications/preferences/", notification_preferences_view, name="notification-preferences"),
-    path("notifications/pace/", pace_status_view, name="pace-status"),
-    path("notifications/dismiss/", dismiss_pace_notification_view, name="dismiss-pace"),
-    path("notifications/reminders/", reminder_view, name="meeting-reminders"),
 ]

backend/apps/groups/views.py

@@ -1,207 +1,331 @@
 from __future__ import annotations
 
-from django.db.models import QuerySet
-from rest_framework import permissions, status, viewsets
-from rest_framework.decorators import action, api_view, permission_classes
+from django.db.models import Count, Prefetch, QuerySet
+from rest_framework import status, viewsets
+from rest_framework.decorators import action
 from rest_framework.permissions import IsAuthenticated
 from rest_framework.request import Request
 from rest_framework.response import Response
 
-from apps.books.models import EBook
-from apps.groups.models import (
-    GroupMeeting,
-    GroupMembership,
-    NotificationPreference,
-    PaceNotification,
-    NotificationStatus,
-    ReadingGroup,
-)
+from apps.groups.models import Group, GroupInvite, GroupMember, GroupRole, JoinRequest, JoinRequestStatus
+from apps.groups.permissions import IsGroupAdmin, IsGroupMember
 from apps.groups.serializers import (
-    GroupMeetingSerializer,
-    GroupMembershipSerializer,
-    NotificationPreferenceSerializer,
-    PaceNotificationSerializer,
-    PaceStatusSerializer,
-    ReadingGroupSerializer,
-    ReminderSerializer,
-)
-from apps.groups.services.pace import (
-    calculate_pace,
-    get_reminder_meetings,
-    should_send_notification,
+    GroupCreateSerializer,
+    GroupDetailSerializer,
+    GroupInviteCreateSerializer,
+    GroupInviteSerializer,
+    GroupListSerializer,
+    GroupMemberSerializer,
+    GroupUpdateSerializer,
+    JoinRequestSerializer,
+    JoinViaInviteSerializer,
+    RoleUpdateSerializer,
 )
 
 
-class IsGroupMember(permissions.BasePermission):
-    """Only allow group members to access group resources."""
-
-    def has_object_permission(self, request: Request, view: object, obj: ReadingGroup) -> bool:
-        return obj.memberships.filter(user=request.user).exists()
-
-
-class ReadingGroupViewSet(viewsets.ModelViewSet):
-    permission_classes = [IsAuthenticated, IsGroupMember]
-    serializer_class = ReadingGroupSerializer
-
-    def get_queryset(self) -> QuerySet[ReadingGroup]:
-        return (
-            ReadingGroup.objects.filter(memberships__user=self.request.user)
-            .prefetch_related("memberships", "meetings")
-            .distinct()
-        )
-
-    def perform_create(self, serializer) -> None:
-        group = serializer.save(created_by=self.request.user)
-        GroupMembership.objects.create(
-            user=self.request.user,
-            group=group,
-            role="admin",
-        )
-
-    @action(detail=False, methods=["get"], url_path="all")
-    def all_groups(self, request: Request) -> Response:
-        """Return all groups (for discovery)."""
-        qs = ReadingGroup.objects.all().prefetch_related("memberships", "meetings")
-        page = self.paginate_queryset(qs)
-        if page is not None:
-            serializer = self.get_serializer(page, many=True)
-            return self.get_paginated_response(serializer.data)
-        serializer = self.get_serializer(qs, many=True)
-        return Response(serializer.data)
-
-
-class GroupMeetingViewSet(viewsets.ModelViewSet):
+class GroupViewSet(viewsets.ModelViewSet):
     permission_classes = [IsAuthenticated]
-    serializer_class = GroupMeetingSerializer
 
-    def get_queryset(self) -> QuerySet[GroupMeeting]:
-        user_group_ids = (
-            GroupMembership.objects.filter(user=self.request.user)
-            .values_list("group_id", flat=True)
-        )
-        return GroupMeeting.objects.filter(group_id__in=user_group_ids).select_related(
-            "group"
-        )
+    def get_serializer_class(self):
+        if self.action == "create":
+            return GroupCreateSerializer
+        if self.action in ("update", "partial_update"):
+            return GroupUpdateSerializer
+        if self.action == "retrieve":
+            return GroupDetailSerializer
+        return GroupListSerializer
 
-    def perform_create(self, serializer) -> None:
-        group = serializer.validated_data["group"]
-        if not group.memberships.filter(user=self.request.user).exists():
-            raise permissions.PermissionDenied("You must be a group member to create meetings.")
-        serializer.save()
+    def get_queryset(self) -> QuerySet[Group]:
+        user = self.request.user
+        qs = Group.objects.filter(memberships__user=user).distinct()
+        qs = qs.annotate(_member_count=Count("memberships"))
+        if self.action in ("list", "retrieve"):
+            qs = qs.prefetch_related(
+                Prefetch(
+                    "memberships",
+                    queryset=GroupMember.objects.select_related("user").order_by("joined_at"),
+                )
+            )
+        return qs
 
-    @action(detail=False, methods=["get"], url_path="upcoming")
-    def upcoming(self, request: Request) -> Response:
-        """Return upcoming meetings for the user's groups (within 3 days)."""
-        from django.utils import timezone
-        from datetime import timedelta
-
-        now = timezone.now()
-        three_days = now + timedelta(days=3)
-        qs = self.get_queryset().filter(
-            scheduled_at__gte=now,
-            scheduled_at__lte=three_days,
-        )
-        serializer = self.get_serializer(qs, many=True)
-        return Response(serializer.data)
-
-
-@api_view(["GET", "PATCH"])
-@permission_classes([IsAuthenticated])
-def notification_preferences_view(request: Request) -> Response:
-    """Get or update notification preferences for the current user."""
-    pref, _created = NotificationPreference.objects.get_or_create(user=request.user)
-
-    if request.method == "GET":
-        serializer = NotificationPreferenceSerializer(pref)
-        return Response(serializer.data)
-
-    serializer = NotificationPreferenceSerializer(pref, data=request.data, partial=True)
-    serializer.is_valid(raise_exception=True)
-    serializer.save()
-    return Response(serializer.data)
-
-
-@api_view(["GET"])
-@permission_classes([IsAuthenticated])
-def pace_status_view(request: Request) -> Response:
-    """Get reading pace status for the current user's upcoming meetings."""
-    ebook_id = request.query_params.get("ebook_id")
-    ebook: EBook | None = None
-
-    if ebook_id:
+    def get_object(self) -> Group:
+        obj = super().get_object()
+        # Cache the requesting user's membership for serializers
         try:
-            ebook = EBook.objects.select_related("reading_progress").prefetch_related("chapters").get(
-                pk=ebook_id, user=request.user
-            )
-        except EBook.DoesNotExist:
+            obj._user_membership = obj.memberships.get(user=self.request.user)
+        except GroupMember.DoesNotExist:
+            obj._user_membership = None
+        return obj
+
+    def perform_create(self, serializer: GroupCreateSerializer) -> Group:
+        return serializer.save()
+
+    def perform_destroy(self, instance: Group) -> None:
+        # Only admin can delete/dissolve the group
+        if not GroupMember.objects.filter(
+            group=instance, user=self.request.user, role=GroupRole.ADMIN
+        ).exists():
+            from rest_framework.exceptions import PermissionDenied
+
+            raise PermissionDenied("Only group admins can delete the group.")
+        instance.delete()
+
+    # ---- Members ----
+
+    @action(detail=True, methods=["get"], permission_classes=[IsAuthenticated, IsGroupMember])
+    def members(self, request: Request, pk: str | None = None) -> Response:
+        """List all members of the group."""
+        group = self.get_object()
+        memberships = group.memberships.select_related("user").order_by("joined_at")
+        serializer = GroupMemberSerializer(memberships, many=True)
+        return Response(serializer.data)
+
+    @action(
+        detail=True,
+        methods=["delete"],
+        url_path="members/(?P<user_id>[^/.]+)",
+        permission_classes=[IsAuthenticated, IsGroupAdmin],
+    )
+    def remove_member(self, request: Request, pk: str | None = None, user_id: str | None = None) -> Response:
+        """Admin removes a member from the group."""
+        group = self.get_object()
+        try:
+            membership = GroupMember.objects.get(group=group, user_id=user_id)
+        except GroupMember.DoesNotExist:
+            return Response({"error": "Member not found."}, status=status.HTTP_404_NOT_FOUND)
+
+        if membership.user == request.user:
             return Response(
-                {"error": "EBook not found."}, status=status.HTTP_404_NOT_FOUND
+                {"error": "Admins cannot remove themselves. Use leave instead, or transfer admin first."},
+                status=status.HTTP_400_BAD_REQUEST,
             )
 
-    pace_data = calculate_pace(request.user, ebook=ebook)
-    serializer = PaceStatusSerializer(pace_data, many=True)
-    return Response(serializer.data)
+        membership.delete()
+        return Response(status=status.HTTP_204_NO_CONTENT)
 
+    @action(
+        detail=True,
+        methods=["patch"],
+        url_path="members/(?P<user_id>[^/.]+)/role",
+        permission_classes=[IsAuthenticated, IsGroupAdmin],
+    )
+    def update_member_role(self, request: Request, pk: str | None = None, user_id: str | None = None) -> Response:
+        """Admin transfers admin role or changes member role."""
+        group = self.get_object()
+        serializer = RoleUpdateSerializer(data=request.data, context={"group": group})
+        serializer.is_valid(raise_exception=True)
 
-@api_view(["POST"])
-@permission_classes([IsAuthenticated])
-def dismiss_pace_notification_view(request: Request) -> Response:
-    """Dismiss a pace notification so it won't show again."""
-    meeting_id = request.data.get("meeting_id")
-    ebook_id = request.data.get("ebook_id")
+        try:
+            membership = GroupMember.objects.get(group=group, user_id=user_id)
+        except GroupMember.DoesNotExist:
+            return Response({"error": "Member not found."}, status=status.HTTP_404_NOT_FOUND)
 
-    if not meeting_id or not ebook_id:
+        membership.role = serializer.validated_data["role"]
+        membership.save(update_fields=["role"])
+
+        if serializer.validated_data["role"] == GroupRole.ADMIN and membership.user != request.user:
+            # Downgrade the current admin to member
+            GroupMember.objects.filter(group=group, user=request.user).update(role=GroupRole.MEMBER)
+
+        return Response(GroupMemberSerializer(membership).data)
+
+    @action(detail=True, methods=["post"], permission_classes=[IsAuthenticated, IsGroupMember])
+    def leave(self, request: Request, pk: str | None = None) -> Response:
+        """Member leaves the group. If admin is last admin, dissolve the group."""
+        group = self.get_object()
+        membership = GroupMember.objects.filter(group=group, user=request.user).first()
+
+        if not membership:
+            return Response({"error": "You are not a member of this group."}, status=status.HTTP_400_BAD_REQUEST)
+
+        if membership.role == GroupRole.ADMIN:
+            admin_count = GroupMember.objects.filter(group=group, role=GroupRole.ADMIN).count()
+            if admin_count <= 1:
+                # Last admin leaving — dissolve the group
+                group.delete()
+                return Response({"detail": "You were the last admin. The group has been dissolved."})
+
+        membership.delete()
+        return Response({"detail": "You have left the group."})
+
+    # ---- Invites ----
+
+    @action(detail=True, methods=["get", "post"], permission_classes=[IsAuthenticated, IsGroupAdmin])
+    def invites(self, request: Request, pk: str | None = None) -> Response:
+        """List or create invites for the group."""
+        group = self.get_object()
+
+        if request.method == "GET":
+            invites_qs = group.invites.select_related("created_by").order_by("-created_at")
+            serializer = GroupInviteSerializer(invites_qs, many=True, context={"request": request})
+            return Response(serializer.data)
+
+        serializer = GroupInviteCreateSerializer(
+            data=request.data,
+            context={"group": group, "request": request},
+        )
+        serializer.is_valid(raise_exception=True)
+        invite = serializer.save()
         return Response(
-            {"error": "meeting_id and ebook_id are required."},
-            status=status.HTTP_400_BAD_REQUEST,
+            GroupInviteSerializer(invite, context={"request": request}).data,
+            status=status.HTTP_201_CREATED,
         )
 
-    PaceNotification.objects.filter(
-        user=request.user,
-        meeting_id=meeting_id,
-        ebook_id=ebook_id,
-        status=NotificationStatus.PENDING,
-    ).update(status=NotificationStatus.DISMISSED)
+    @action(
+        detail=True,
+        methods=["delete"],
+        url_path="invites/(?P<invite_id>[^/.]+)",
+        permission_classes=[IsAuthenticated, IsGroupAdmin],
+    )
+    def revoke_invite(self, request: Request, pk: str | None = None, invite_id: str | None = None) -> Response:
+        """Revoke an invite by deactivating it."""
+        group = self.get_object()
+        try:
+            invite = GroupInvite.objects.get(id=invite_id, group=group)
+        except GroupInvite.DoesNotExist:
+            return Response({"error": "Invite not found."}, status=status.HTTP_404_NOT_FOUND)
 
-    return Response({"status": "dismissed"})
+        invite.is_active = False
+        invite.save(update_fields=["is_active"])
+        return Response(status=status.HTTP_204_NO_CONTENT)
+
+    # ---- Join Requests ----
+
+    @action(detail=True, methods=["get"], permission_classes=[IsAuthenticated, IsGroupAdmin])
+    def requests(self, request: Request, pk: str | None = None) -> Response:
+        """List pending join requests for the group (admin only)."""
+        group = self.get_object()
+        join_requests = group.join_requests.select_related("user", "invite").order_by("-created_at")
+        serializer = JoinRequestSerializer(join_requests, many=True)
+        return Response(serializer.data)
+
+    @action(
+        detail=True,
+        methods=["post"],
+        url_path="requests/(?P<request_id>[^/.]+)/approve",
+        permission_classes=[IsAuthenticated, IsGroupAdmin],
+    )
+    def approve_request(self, request: Request, pk: str | None = None, request_id: str | None = None) -> Response:
+        """Approve a pending join request."""
+        group = self.get_object()
+        try:
+            join_request = JoinRequest.objects.get(id=request_id, group=group, status=JoinRequestStatus.PENDING)
+        except JoinRequest.DoesNotExist:
+            return Response({"error": "Pending join request not found."}, status=status.HTTP_404_NOT_FOUND)
+
+        join_request.status = JoinRequestStatus.APPROVED
+        join_request.save(update_fields=["status"])
+
+        GroupMember.objects.get_or_create(
+            group=group,
+            user=join_request.user,
+            defaults={"role": GroupRole.MEMBER},
+        )
+
+        # Increment invite use count
+        if join_request.invite:
+            join_request.invite.use_count += 1
+            join_request.invite.save(update_fields=["use_count"])
+
+        return Response(JoinRequestSerializer(join_request).data)
+
+    @action(
+        detail=True,
+        methods=["post"],
+        url_path="requests/(?P<request_id>[^/.]+)/reject",
+        permission_classes=[IsAuthenticated, IsGroupAdmin],
+    )
+    def reject_request(self, request: Request, pk: str | None = None, request_id: str | None = None) -> Response:
+        """Reject a pending join request."""
+        group = self.get_object()
+        try:
+            join_request = JoinRequest.objects.get(id=request_id, group=group, status=JoinRequestStatus.PENDING)
+        except JoinRequest.DoesNotExist:
+            return Response({"error": "Pending join request not found."}, status=status.HTTP_404_NOT_FOUND)
+
+        join_request.status = JoinRequestStatus.REJECTED
+        join_request.save(update_fields=["status"])
+        return Response(JoinRequestSerializer(join_request).data)
 
 
-@api_view(["GET"])
-@permission_classes([IsAuthenticated])
-def reminder_view(request: Request) -> Response:
-    """Get pre-meeting reminders for meetings within 24 hours."""
-    pref, _ = NotificationPreference.objects.get_or_create(user=request.user)
-    if not pref.reminder_enabled:
-        return Response([])
+class JoinGroupViewSet(viewsets.GenericViewSet):
+    """Public(ish) endpoint for joining a group via an invite code."""
 
-    meetings = get_reminder_meetings(request.user)
-    now_dt = __import__("django").utils.timezone.now()
+    permission_classes = [IsAuthenticated]
 
-    reminders = []
-    for mtg in meetings:
-        group_ebook = mtg.group.ebook
-        ebook: EBook | None = group_ebook
-        if not ebook:
-            ebooks = list(
-                EBook.objects.filter(reading_groups=mtg.group).select_related("reading_progress")[:1]
-            )
-            ebook = ebooks[0] if ebooks else None
+    @action(detail=False, methods=["get"], url_path="(?P<code>[^/.]+)")
+    def validate_invite(self, request: Request, code: str | None = None) -> Response:
+        """Check if an invite code is valid and show group info."""
+        try:
+            invite = GroupInvite.objects.select_related("group", "group__created_by").get(code=code)
+        except GroupInvite.DoesNotExist:
+            return Response({"error": "Invalid invite code."}, status=status.HTTP_404_NOT_FOUND)
 
-        if not ebook:
-            continue
+        if not invite.is_active:
+            return Response({"error": "This invite is no longer active."}, status=status.HTTP_410_GONE)
 
-        hours_until = max(0, int((mtg.scheduled_at - now_dt).total_seconds() / 3600))
-        reminders.append({
-            "meeting_id": mtg.pk,
-            "meeting_title": mtg.title or mtg.target_section_label,
-            "scheduled_at": mtg.scheduled_at.isoformat(),
-            "target_section": mtg.target_section,
-            "target_section_label": mtg.target_section_label,
-            "group_name": mtg.group.name,
-            "hours_until": hours_until,
-            "ebook_id": ebook.pk,
-            "ebook_title": ebook.title,
+        if invite.max_uses > 0 and invite.use_count >= invite.max_uses:
+            return Response({"error": "This invite has reached its maximum uses."}, status=status.HTTP_410_GONE)
+
+        return Response({
+            "group": {
+                "id": invite.group.id,
+                "name": invite.group.name,
+                "description": invite.group.description,
+                "created_by_email": invite.group.created_by.email,
+                "member_count": invite.group.memberships.count(),
+            },
+            "invite": {
+                "code": str(invite.code),
+                "created_by_email": invite.created_by.email,
+            },
         })
 
-    serializer = ReminderSerializer(reminders, many=True)
-    return Response(serializer.data)
+    @action(detail=False, methods=["post"], url_path="(?P<code>[^/.]+)")
+    def join(self, request: Request, code: str | None = None) -> Response:
+        """Join a group via invite code."""
+        try:
+            invite = GroupInvite.objects.select_related("group").get(code=code)
+        except GroupInvite.DoesNotExist:
+            return Response({"error": "Invalid invite code."}, status=status.HTTP_404_NOT_FOUND)
+
+        if not invite.is_active:
+            return Response({"error": "This invite is no longer active."}, status=status.HTTP_410_GONE)
+
+        if invite.max_uses > 0 and invite.use_count >= invite.max_uses:
+            return Response({"error": "This invite has reached its maximum uses."}, status=status.HTTP_410_GONE)
+
+        group = invite.group
+
+        # Check if already a member
+        if GroupMember.objects.filter(group=group, user=request.user).exists():
+            return Response(
+                {"detail": "You are already a member of this group.", "group_id": group.id},
+                status=status.HTTP_200_OK,
+            )
+
+        # Check for existing pending request
+        existing_request = JoinRequest.objects.filter(
+            group=group, user=request.user, status=JoinRequestStatus.PENDING
+        ).first()
+        if existing_request:
+            return Response(
+                JoinRequestSerializer(existing_request).data,
+                status=status.HTTP_200_OK,
+            )
+
+        # Create join request or add directly (direct join for now — simple invite flow)
+        member = GroupMember.objects.create(group=group, user=request.user, role=GroupRole.MEMBER)
+        invite.use_count += 1
+        invite.save(update_fields=["use_count"])
+
+        # Also create a join request record for tracking
+        JoinRequest.objects.create(
+            group=group,
+            user=request.user,
+            invite=invite,
+            status=JoinRequestStatus.APPROVED,
+        )
+
+        serializer = GroupDetailSerializer(group, context={"request": request})
+        return Response(serializer.data, status=status.HTTP_201_CREATED)

backend/config/urls.py

@@ -8,7 +8,7 @@ urlpatterns = [
     path("api/books/", include("apps.books.urls")),
     path("api/annotations/", include("apps.annotations.urls")),
     path("api/reader/", include("apps.reader.urls")),
-    path("api/groups/", include("apps.groups.urls")),
+    path("api/", include("apps.groups.urls")),
 ]
 
 if settings.DEBUG:

frontend/src/App.tsx

@@ -12,6 +12,10 @@ const AddBookPage = lazy(() => import("./pages/AddBook").then((m) => ({ default:
 const SettingsPage = lazy(() => import("./pages/Settings").then((m) => ({ default: m.SettingsPage })));
 const BookmarksNotesPage = lazy(() => import("./components/annotations/BookmarksNotesPage").then((m) => ({ default: m.BookmarksNotesPage })));
 const ReadingPage = lazy(() => import("./pages/ReadingPage").then((m) => ({ default: m.default })));
+const GroupsListPage = lazy(() => import("./pages/GroupsListPage").then((m) => ({ default: m.GroupsListPage })));
+const GroupDetailPage = lazy(() => import("./pages/GroupDetailPage").then((m) => ({ default: m.GroupDetailPage })));
+const CreateGroupPage = lazy(() => import("./pages/CreateGroupPage").then((m) => ({ default: m.CreateGroupPage })));
+const JoinGroupPage = lazy(() => import("./pages/JoinGroupPage").then((m) => ({ default: m.JoinGroupPage })));
 
 const AuthPage = lazy(() => import("./pages/AuthPage"));
 
@@ -45,6 +49,10 @@ function AppRoutes() {
         <Route path="/add" element={<ProtectedRoute><AddBookPage /></ProtectedRoute>} />
         <Route path="/settings" element={<ProtectedRoute><SettingsPage /></ProtectedRoute>} />
         <Route path="/bookmarks-notes/:bookId?" element={<ProtectedRoute><BookmarksNotesPage /></ProtectedRoute>} />
+        <Route path="/groups" element={<ProtectedRoute><GroupsListPage /></ProtectedRoute>} />
+        <Route path="/groups/create" element={<ProtectedRoute><CreateGroupPage /></ProtectedRoute>} />
+        <Route path="/groups/join/:code" element={<ProtectedRoute><JoinGroupPage /></ProtectedRoute>} />
+        <Route path="/groups/:id" element={<ProtectedRoute><GroupDetailPage /></ProtectedRoute>} />
         <Route path="*" element={<Navigate to="/" replace />} />
       </Routes>
     </Suspense>

frontend/src/api/groups.ts

@@ -1,57 +1,100 @@
 import api from "./client";
 import type {
-  GroupMeeting,
-  MeetingReminder,
-  NotificationPreferences,
-  PaceStatus,
-  ReadingGroup,
-} from "../types/notifications";
+  CreateGroupPayload,
+  CreateInvitePayload,
+  GroupDetail,
+  GroupInvite,
+  GroupListItem,
+  InviteValidation,
+  JoinRequest,
+  UpdateGroupPayload,
+} from "../../packages/shared/src/types";
 
 export const groupsApi = {
-  async getPaceStatus(ebookId?: number): Promise<PaceStatus[]> {
-    const params: Record<string, string> = {};
-    if (ebookId) params.ebook_id = String(ebookId);
-    const { data } = await api.get<PaceStatus[]>("/groups/notifications/pace/", { params });
-    return data;
-  },
+  // ---- Group CRUD ----
 
-  async getPreferences(): Promise<NotificationPreferences> {
-    const { data } = await api.get<NotificationPreferences>("/groups/notifications/preferences/");
-    return data;
-  },
-
-  async updatePreferences(
-    prefs: Partial<NotificationPreferences>,
-  ): Promise<NotificationPreferences> {
-    const { data } = await api.patch<NotificationPreferences>(
-      "/groups/notifications/preferences/",
-      prefs,
-    );
-    return data;
-  },
-
-  async dismissPaceNotification(meetingId: number, ebookId: number): Promise<void> {
-    await api.post("/groups/notifications/dismiss/", {
-      meeting_id: meetingId,
-      ebook_id: ebookId,
-    });
-  },
-
-  async getReminders(): Promise<MeetingReminder[]> {
-    const { data } = await api.get<MeetingReminder[]>("/groups/notifications/reminders/");
-    return data;
-  },
-
-  async getGroups(): Promise<ReadingGroup[]> {
-    const { data } = await api.get<{ count: number; results: ReadingGroup[] } | ReadingGroup[]>(
-      "/groups/groups/",
-    );
+  async listGroups(): Promise<GroupListItem[]> {
+    const { data } = await api.get<{ count: number; results: GroupListItem[] } | GroupListItem[]>("/groups/");
     if (Array.isArray(data)) return data;
     return data.results ?? [];
   },
 
-  async getUpcomingMeetings(): Promise<GroupMeeting[]> {
-    const { data } = await api.get<GroupMeeting[]>("/groups/meetings/upcoming/");
+  async getGroup(id: number): Promise<GroupDetail> {
+    const { data } = await api.get<GroupDetail>(`/groups/${id}/`);
+    return data;
+  },
+
+  async createGroup(payload: CreateGroupPayload): Promise<GroupDetail> {
+    const { data } = await api.post<GroupDetail>("/groups/", payload);
+    return data;
+  },
+
+  async updateGroup(id: number, payload: UpdateGroupPayload): Promise<GroupDetail> {
+    const { data } = await api.patch<GroupDetail>(`/groups/${id}/`, payload);
+    return data;
+  },
+
+  async deleteGroup(id: number): Promise<void> {
+    await api.delete(`/groups/${id}/`);
+  },
+
+  // ---- Members ----
+
+  async removeMember(groupId: number, userId: number): Promise<void> {
+    await api.delete(`/groups/${groupId}/members/${userId}/`);
+  },
+
+  async updateMemberRole(groupId: number, userId: number, role: "admin" | "member"): Promise<void> {
+    await api.patch(`/groups/${groupId}/members/${userId}/role/`, { role });
+  },
+
+  async leaveGroup(groupId: number): Promise<{ detail: string }> {
+    const { data } = await api.post<{ detail: string }>(`/groups/${groupId}/leave/`);
+    return data;
+  },
+
+  // ---- Invites ----
+
+  async listInvites(groupId: number): Promise<GroupInvite[]> {
+    const { data } = await api.get<GroupInvite[]>(`/groups/${groupId}/invites/`);
+    return data;
+  },
+
+  async createInvite(groupId: number, payload: CreateInvitePayload = {}): Promise<GroupInvite> {
+    const { data } = await api.post<GroupInvite>(`/groups/${groupId}/invites/`, payload);
+    return data;
+  },
+
+  async revokeInvite(groupId: number, inviteId: number): Promise<void> {
+    await api.delete(`/groups/${groupId}/invites/${inviteId}/`);
+  },
+
+  // ---- Join Requests ----
+
+  async listJoinRequests(groupId: number): Promise<JoinRequest[]> {
+    const { data } = await api.get<JoinRequest[]>(`/groups/${groupId}/requests/`);
+    return data;
+  },
+
+  async approveRequest(groupId: number, requestId: number): Promise<JoinRequest> {
+    const { data } = await api.post<JoinRequest>(`/groups/${groupId}/requests/${requestId}/approve/`);
+    return data;
+  },
+
+  async rejectRequest(groupId: number, requestId: number): Promise<JoinRequest> {
+    const { data } = await api.post<JoinRequest>(`/groups/${groupId}/requests/${requestId}/reject/`);
+    return data;
+  },
+
+  // ---- Join via Invite ----
+
+  async validateInvite(code: string): Promise<InviteValidation> {
+    const { data } = await api.get<InviteValidation>(`/join/${code}/`);
+    return data;
+  },
+
+  async joinViaInvite(code: string): Promise<GroupDetail> {
+    const { data } = await api.post<GroupDetail>(`/join/${code}/`);
     return data;
   },
 };

frontend/src/components/notifications/PaceNotification.tsx

@@ -1,119 +0,0 @@
-import { useEffect, useState } from "react";
-import { useTranslation } from "react-i18n-lite";
-import { groupsApi } from "../api/groups";
-import type { PaceStatus } from "../types/notifications";
-
-interface PaceNotificationProps {
-  ebookId?: number;
-}
-
-export function PaceNotification({ ebookId }: PaceNotificationProps) {
-  const { t } = useTranslation();
-  const [paceItems, setPaceItems] = useState<PaceStatus[]>([]);
-  const [loading, setLoading] = useState(true);
-  const [dismissed, setDismissed] = useState<Set<string>>(new Set());
-
-  useEffect(() => {
-    const load = async () => {
-      try {
-        const data = await groupsApi.getPaceStatus(ebookId);
-        setPaceItems(data);
-      } catch {
-        // Silently fail — notifications are non-critical
-      } finally {
-        setLoading(false);
-      }
-    };
-    void load();
-  }, [ebookId]);
-
-  const handleDismiss = async (meetingId: number, itemEbookId: number) => {
-    const key = `${meetingId}-${itemEbookId}`;
-    setDismissed((prev) => new Set(prev).add(key));
-    try {
-      await groupsApi.dismissPaceNotification(meetingId, itemEbookId);
-    } catch {
-      // Best effort dismissal
-    }
-  };
-
-  if (loading || paceItems.length === 0) return null;
-
-  const visibleItems = paceItems.filter(
-    (p) => !dismissed.has(`${p.meeting_id}-${p.ebook_id}`),
-  );
-  if (visibleItems.length === 0) return null;
-
-  return (
-    <div style={{ display: "flex", flexDirection: "column", gap: 8, padding: "12px 0" }}>
-      {visibleItems.map((item) => {
-        const isBehind = item.status === "behind";
-        const isAhead = item.status === "ahead" || item.status === "completed";
-        const isOnTrack = item.status === "on_track";
-
-        const bgColor = isBehind ? "#fde8e8" : isAhead ? "#d4edda" : "#e8f4fd";
-        const borderColor = isBehind ? "#e74c3c" : isAhead ? "#27ae60" : "#3498db";
-        const textColor = isBehind ? "#a71d2a" : isAhead ? "#155724" : "#0c5460";
-
-        return (
-          <div
-            key={`${item.meeting_id}-${item.ebook_id}`}
-            style={{
-              background: bgColor,
-              border: `1px solid ${borderColor}`,
-              borderRadius: 8,
-              padding: "12px 16px",
-              display: "flex",
-              alignItems: "flex-start",
-              justifyContent: "space-between",
-              gap: 12,
-            }}
-          >
-            <div style={{ flex: 1 }}>
-              <div style={{ fontSize: 14, fontWeight: 600, color: textColor, marginBottom: 4 }}>
-                {isBehind
-                  ? `Behind schedule — catch up ${item.sections_to_catch_up} section${item.sections_to_catch_up !== 1 ? "s" : ""}`
-                  : isOnTrack
-                    ? "On track — keep going!"
-                    : item.status === "completed"
-                      ? "Meeting target completed!"
-                      : "Ahead of schedule — great job!"}
-              </div>
-              <div style={{ fontSize: 13, color: textColor, opacity: 0.85 }}>
-                {item.meeting_title || `Target: ${item.target_section_label || `Section ${item.target_section}`}`}
-                {" — "}
-                {item.ebook_title}
-              </div>
-              <div style={{ fontSize: 12, color: textColor, opacity: 0.7, marginTop: 2 }}>
-                {isBehind
-                  ? `Currently at section ${item.current_section}, need section ${item.target_section}`
-                  : `Section ${item.current_section} of ${item.target_section}`}
-                {item.days_until_meeting > 0 &&
-                  ` · ${item.days_until_meeting} day${item.days_until_meeting !== 1 ? "s" : ""} until meeting`}
-                {item.days_until_meeting === 0 && " · Meeting today"}
-              </div>
-            </div>
-            <button
-              type="button"
-              onClick={() => handleDismiss(item.meeting_id, item.ebook_id)}
-              style={{
-                background: "none",
-                border: "none",
-                color: textColor,
-                fontSize: 20,
-                cursor: "pointer",
-                padding: "0 4px",
-                lineHeight: 1,
-                opacity: 0.6,
-                flexShrink: 0,
-              }}
-              title="Dismiss"
-            >
-              ×
-            </button>
-          </div>
-        );
-      })}
-    </div>
-  );
-}

frontend/src/components/notifications/ReadingPaceBanner.tsx

@@ -1,71 +0,0 @@
-import { useEffect, useState } from "react";
-import { groupsApi } from "../../api/groups";
-import type { PaceStatus } from "../../types/notifications";
-
-interface ReadingPaceBannerProps {
-  ebookId: number;
-  currentSection: number;
-}
-
-export function ReadingPaceBanner({ ebookId, currentSection }: ReadingPaceBannerProps) {
-  const [paceItems, setPaceItems] = useState<PaceStatus[]>([]);
-
-  useEffect(() => {
-    const load = async () => {
-      try {
-        const data = await groupsApi.getPaceStatus(ebookId);
-        setPaceItems(data);
-      } catch {
-        // Silently fail
-      }
-    };
-    void load();
-  }, [ebookId, currentSection]);
-
-  if (paceItems.length === 0) return null;
-
-  // Only show if user is one section away from target
-  const relevantItems = paceItems.filter(
-    (p) => Math.abs(p.target_section - p.current_section) <= 1 && p.status !== "completed",
-  );
-
-  if (relevantItems.length === 0) return null;
-
-  return (
-    <div
-      style={{
-        background: "linear-gradient(135deg, #667eea 0%, #764ba2 100%)",
-        color: "#fff",
-        padding: "10px 16px",
-        fontSize: 13,
-        fontWeight: 500,
-        textAlign: "center",
-        display: "flex",
-        alignItems: "center",
-        justifyContent: "center",
-        gap: 8,
-        flexWrap: "wrap",
-        position: "sticky",
-        top: 0,
-        zIndex: 10,
-      }}
-    >
-      {relevantItems.map((item) => {
-        const isAlmostThere = item.sections_to_catch_up === 1;
-        const isAtTarget = item.sections_to_catch_up === 0;
-
-        return (
-          <span key={item.meeting_id}>
-            {isAtTarget
-              ? `You've reached the target for ${item.meeting_title || `Section ${item.target_section}`}!`
-              : isAlmostThere
-                ? `Almost there! Just 1 section to go for ${item.meeting_title || `Section ${item.target_section}`}.`
-                : `You should be on ${item.target_section_label || `Section ${item.target_section}`} by the upcoming meeting.`}
-            {item.days_until_meeting > 0 &&
-              ` (${item.days_until_meeting} day${item.days_until_meeting !== 1 ? "s" : ""} left)`}
-          </span>
-        );
-      })}
-    </div>
-  );
-}

frontend/src/components/reader/EpubReadingView.tsx

@@ -22,7 +22,6 @@ import { SelectionPopover } from "./SelectionPopover";
 import { BookMarkersPanel } from "./BookMarkersPanel";
 import { BookmarkReaderRail } from "./BookmarkReaderRail";
 import { ResumeReadingButton } from "./ResumeReadingButton";
-import { ReadingPaceBanner } from "../notifications/ReadingPaceBanner";
 import type { MarkerEntry } from "@/types";
 
 const ReaderToolbar = lazy(() => import("./ReaderToolbar"));
@@ -131,10 +130,6 @@ export function EpubReadingView({ book, bookId, initialEpubLocation }: EpubReadi
 
   return (
     <ReaderSuspenseShell theme={settings.theme}>
-        <ReadingPaceBanner
-          ebookId={bookId}
-          currentSection={tocItems.length > 0 ? Math.max(1, Math.ceil((progress / 100) * tocItems.length)) : 0}
-        />
         <ReaderToolbar
           bookTitle={book.title}
           chapterTitle={chapterTitle || t("reader.reading")}

frontend/src/components/reader/PdfReadingView.tsx

@@ -24,7 +24,6 @@ import { BookmarkReaderRail } from "./BookmarkReaderRail";
 import { ResumeReadingButton } from "./ResumeReadingButton";
 import { PdfLimitationsNotice } from "./PdfLimitationsNotice";
 import { PdfViewer } from "./PdfViewer";
-import { ReadingPaceBanner } from "../notifications/ReadingPaceBanner";
 import type { MarkerEntry } from "@/types";
 
 const ReaderToolbar = lazy(() => import("./ReaderToolbar"));
@@ -171,10 +170,6 @@ export function PdfReadingView({ book, bookId, initialAnchor }: PdfReadingViewPr
 
   return (
     <ReaderSuspenseShell theme={settings.theme}>
-        <ReadingPaceBanner
-          ebookId={bookId}
-          currentSection={currentPage}
-        />
         <ReaderToolbar
           bookTitle={book.title}
           chapterTitle={chapterTitle || t("reader.reading")}

frontend/src/pages/CreateGroupPage.tsx

@@ -0,0 +1,104 @@
+import React, { useState } from "react";
+import { useNavigate } from "react-router-dom";
+import { groupsApi } from "../api/groups";
+import { useToast } from "../hooks/useToast";
+
+const S = {
+  container: { maxWidth: 500, margin: "0 auto", padding: "24px 16px" } satisfies React.CSSProperties,
+  backBtn: {
+    background: "none", border: "none", color: "#3b82f6", fontSize: 14, cursor: "pointer",
+    padding: 0, marginBottom: 16, minHeight: 44, minWidth: 44,
+  } satisfies React.CSSProperties,
+  title: { fontSize: 24, fontWeight: 700, marginBottom: 24 } satisfies React.CSSProperties,
+  label: { display: "block", fontSize: 14, fontWeight: 500, marginBottom: 6 } satisfies React.CSSProperties,
+  input: {
+    width: "100%", padding: "10px 12px", border: "1px solid #d1d5db", borderRadius: 8,
+    fontSize: 14, marginBottom: 16, boxSizing: "border-box" as const,
+  } satisfies React.CSSProperties,
+  textarea: {
+    width: "100%", padding: "10px 12px", border: "1px solid #d1d5db", borderRadius: 8,
+    fontSize: 14, marginBottom: 16, minHeight: 80, resize: "vertical" as const,
+    boxSizing: "border-box" as const, fontFamily: "inherit",
+  } satisfies React.CSSProperties,
+  submitBtn: (disabled: boolean): React.CSSProperties => ({
+    width: "100%", padding: "12px", backgroundColor: disabled ? "#93c5fd" : "#3b82f6",
+    color: "#fff", border: "none", borderRadius: 8, fontSize: 15, fontWeight: 600,
+    cursor: disabled ? "not-allowed" : "pointer", minHeight: 44,
+  }),
+  errorText: { color: "#ef4444", fontSize: 13, marginBottom: 12 },
+};
+
+export function CreateGroupPage() {
+  const navigate = useNavigate();
+  const { showToast } = useToast();
+
+  const [name, setName] = useState("");
+  const [description, setDescription] = useState("");
+  const [submitting, setSubmitting] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!name.trim()) {
+      setError("Group name is required.");
+      return;
+    }
+    if (name.trim().length < 2) {
+      setError("Group name must be at least 2 characters.");
+      return;
+    }
+    setSubmitting(true);
+    setError(null);
+    try {
+      const group = await groupsApi.createGroup({
+        name: name.trim(),
+        description: description.trim() || undefined,
+      });
+      showToast({ message: "Group created!", variant: "success" });
+      navigate(`/groups/${group.id}`);
+    } catch (err: unknown) {
+      const msg = err instanceof Error ? err.message : "Failed to create group";
+      setError(msg);
+      showToast({ message: msg, variant: "error" });
+    } finally {
+      setSubmitting(false);
+    }
+  };
+
+  return (
+    <div style={S.container}>
+      <button style={S.backBtn} onClick={() => navigate("/groups")}>
+        ← Back to Groups
+      </button>
+      <h1 style={S.title}>Create a Group</h1>
+
+      <form onSubmit={handleSubmit}>
+        {error && <div style={S.errorText}>{error}</div>}
+
+        <label style={S.label} htmlFor="group-name">Group Name *</label>
+        <input
+          id="group-name"
+          style={S.input}
+          value={name}
+          onChange={(e) => setName(e.target.value)}
+          placeholder="e.g., Sci-Fi Book Club"
+          maxLength={256}
+          autoFocus
+        />
+
+        <label style={S.label} htmlFor="group-desc">Description</label>
+        <textarea
+          id="group-desc"
+          style={S.textarea}
+          value={description}
+          onChange={(e) => setDescription(e.target.value)}
+          placeholder="What's this group about? (optional)"
+        />
+
+        <button type="submit" style={S.submitBtn(submitting || !name.trim())} disabled={submitting || !name.trim()}>
+          {submitting ? "Creating..." : "Create Group"}
+        </button>
+      </form>
+    </div>
+  );
+}

frontend/src/pages/GroupDetailPage.tsx

@@ -0,0 +1,334 @@
+import React, { useCallback, useEffect, useState } from "react";
+import { useNavigate, useParams } from "react-router-dom";
+import { groupsApi } from "../api/groups";
+import { useAuth } from "../context/AuthContext";
+import { useToast } from "../hooks/useToast";
+import type { GroupDetail, GroupInvite, GroupMember } from "../../packages/shared/src/types";
+
+const S = {
+  container: { maxWidth: 800, margin: "0 auto", padding: "24px 16px" } satisfies React.CSSProperties,
+  backBtn: {
+    background: "none", border: "none", color: "#3b82f6", fontSize: 14, cursor: "pointer",
+    padding: 0, marginBottom: 16, minHeight: 44, minWidth: 44,
+  } satisfies React.CSSProperties,
+  title: { fontSize: 28, fontWeight: 700, margin: "0 0 4px 0" } satisfies React.CSSProperties,
+  desc: { fontSize: 14, color: "#6b7280", margin: "0 0 20px 0" } satisfies React.CSSProperties,
+  section: { marginTop: 28 } satisfies React.CSSProperties,
+  sectionTitle: { fontSize: 18, fontWeight: 600, marginBottom: 12 } satisfies React.CSSProperties,
+  memberItem: {
+    display: "flex", justifyContent: "space-between", alignItems: "center",
+    padding: "10px 0", borderBottom: "1px solid #f3f4f6",
+  } satisfies React.CSSProperties,
+  memberInfo: { display: "flex", flexDirection: "column" as const },
+  memberName: { fontSize: 14, fontWeight: 500 } satisfies React.CSSProperties,
+  memberEmail: { fontSize: 12, color: "#9ca3af" } satisfies React.CSSProperties,
+  badge: (role: string): React.CSSProperties => ({
+    display: "inline-block", padding: "2px 8px", borderRadius: 6, fontSize: 11, fontWeight: 600,
+    backgroundColor: role === "admin" ? "#dbeafe" : "#f3f4f6",
+    color: role === "admin" ? "#1d4ed8" : "#6b7280",
+  }),
+  removeBtn: {
+    padding: "4px 12px", fontSize: 12, color: "#ef4444", background: "#fef2f2",
+    border: "1px solid #fecaca", borderRadius: 6, cursor: "pointer", minHeight: 32,
+  } satisfies React.CSSProperties,
+  transferBtn: {
+    padding: "4px 12px", fontSize: 12, color: "#3b82f6", background: "#eff6ff",
+    border: "1px solid #bfdbfe", borderRadius: 6, cursor: "pointer", minHeight: 32,
+    marginRight: 8,
+  } satisfies React.CSSProperties,
+  inviteCard: {
+    padding: "12px 16px", border: "1px solid #e5e7eb", borderRadius: 8, marginBottom: 8,
+  } satisfies React.CSSProperties,
+  inviteCode: { fontSize: 13, fontFamily: "monospace", marginBottom: 4 } satisfies React.CSSProperties,
+  inviteMeta: { fontSize: 12, color: "#9ca3af" } satisfies React.CSSProperties,
+  actionBtn: (color: string): React.CSSProperties => ({
+    padding: "8px 16px", backgroundColor: color, color: "#fff", border: "none",
+    borderRadius: 8, fontSize: 13, fontWeight: 600, cursor: "pointer",
+    minHeight: 44, minWidth: 44,
+  }),
+  dangerBtn: {
+    padding: "8px 16px", backgroundColor: "#ef4444", color: "#fff", border: "none",
+    borderRadius: 8, fontSize: 13, fontWeight: 600, cursor: "pointer",
+    minHeight: 44, minWidth: 44,
+  } satisfies React.CSSProperties,
+  leaveBtn: {
+    padding: "8px 16px", backgroundColor: "#fff", color: "#ef4444",
+    border: "1px solid #ef4444", borderRadius: 8, fontSize: 13, fontWeight: 600,
+    cursor: "pointer", minHeight: 44, minWidth: 44,
+  } satisfies React.CSSProperties,
+  inlineBtn: {
+    padding: "4px 10px", fontSize: 12, color: "#ef4444", background: "#fef2f2",
+    border: "1px solid #fecaca", borderRadius: 6, cursor: "pointer", minHeight: 28,
+  } satisfies React.CSSProperties,
+  copyRow: { display: "flex", gap: 8, alignItems: "center", marginBottom: 12 } satisfies React.CSSProperties,
+  input: {
+    flex: 1, padding: "10px 12px", border: "1px solid #d1d5db", borderRadius: 8, fontSize: 14,
+  } satisfies React.CSSProperties,
+  loading: { textAlign: "center" as const, padding: 60, color: "#9ca3af" },
+  error: { textAlign: "center" as const, padding: 40, color: "#ef4444" },
+};
+
+export function GroupDetailPage() {
+  const { id } = useParams<{ id: string }>();
+  const navigate = useNavigate();
+  const { user } = useAuth();
+  const { showToast } = useToast();
+
+  const [group, setGroup] = useState<GroupDetail | null>(null);
+  const [invites, setInvites] = useState<GroupInvite[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [editingName, setEditingName] = useState(false);
+  const [editName, setEditName] = useState("");
+  const [showInviteSection, setShowInviteSection] = useState(false);
+
+  const groupId = Number(id);
+  const isAdmin = group?.user_role === "admin";
+
+  const loadGroup = useCallback(async () => {
+    if (!groupId) return;
+    setLoading(true);
+    setError(null);
+    try {
+      const data = await groupsApi.getGroup(groupId);
+      setGroup(data);
+    } catch (err: unknown) {
+      setError(err instanceof Error ? err.message : "Failed to load group");
+    } finally {
+      setLoading(false);
+    }
+  }, [groupId]);
+
+  const loadInvites = useCallback(async () => {
+    if (!groupId || !isAdmin) return;
+    try {
+      const data = await groupsApi.listInvites(groupId);
+      setInvites(data);
+    } catch {
+      // Silently fail — invites are supplementary
+    }
+  }, [groupId, isAdmin]);
+
+  useEffect(() => {
+    loadGroup();
+  }, [loadGroup]);
+
+  useEffect(() => {
+    if (group && isAdmin) loadInvites();
+  }, [group, isAdmin, loadInvites]);
+
+  const handleRemoveMember = async (userId: number, memberEmail: string) => {
+    if (!confirm(`Remove ${memberEmail} from the group?`)) return;
+    try {
+      await groupsApi.removeMember(groupId, userId);
+      showToast({ message: "Member removed", variant: "success" });
+      loadGroup();
+    } catch (err: unknown) {
+      showToast({ message: "Failed to remove member", variant: "error" });
+    }
+  };
+
+  const handleTransferAdmin = async (userId: number, memberEmail: string) => {
+    if (!confirm(`Transfer admin role to ${memberEmail}? You will become a regular member.`)) return;
+    try {
+      await groupsApi.updateMemberRole(groupId, userId, "admin");
+      showToast({ message: "Admin role transferred", variant: "success" });
+      loadGroup();
+    } catch (err: unknown) {
+      showToast({ message: "Failed to transfer admin", variant: "error" });
+    }
+  };
+
+  const handleLeave = async () => {
+    if (!confirm("Are you sure you want to leave this group?")) return;
+    try {
+      const result = await groupsApi.leaveGroup(groupId);
+      showToast({ message: result.detail || "Left group", variant: "success" });
+      navigate("/groups");
+    } catch (err: unknown) {
+      showToast({ message: "Failed to leave group", variant: "error" });
+    }
+  };
+
+  const handleCreateInvite = async () => {
+    try {
+      const invite = await groupsApi.createInvite(groupId);
+      setInvites((prev) => [invite, ...prev]);
+      showToast({ message: "Invite link created!", variant: "success" });
+    } catch (err: unknown) {
+      showToast({ message: "Failed to create invite", variant: "error" });
+    }
+  };
+
+  const handleRevokeInvite = async (inviteId: number) => {
+    try {
+      await groupsApi.revokeInvite(groupId, inviteId);
+      setInvites((prev) => prev.map((i) => (i.id === inviteId ? { ...i, is_active: false } : i)));
+      showToast({ message: "Invite revoked", variant: "success" });
+    } catch (err: unknown) {
+      showToast({ message: "Failed to revoke invite", variant: "error" });
+    }
+  };
+
+  const handleSaveName = async () => {
+    if (!editName.trim()) return;
+    try {
+      const updated = await groupsApi.updateGroup(groupId, { name: editName.trim() });
+      setGroup(updated);
+      setEditingName(false);
+      showToast({ message: "Group name updated", variant: "success" });
+    } catch (err: unknown) {
+      showToast({ message: "Failed to update group", variant: "error" });
+    }
+  };
+
+  const handleDeleteGroup = async () => {
+    if (!confirm("Delete this group? This cannot be undone.")) return;
+    try {
+      await groupsApi.deleteGroup(groupId);
+      showToast({ message: "Group deleted", variant: "success" });
+      navigate("/groups");
+    } catch (err: unknown) {
+      showToast({ message: "Failed to delete group", variant: "error" });
+    }
+  };
+
+  const copyToClipboard = (text: string) => {
+    navigator.clipboard.writeText(text).then(
+      () => showToast({ message: "Link copied!" }),
+      () => showToast({ message: "Failed to copy", variant: "error" }),
+    );
+  };
+
+  if (loading) return <div style={S.loading}>Loading group...</div>;
+  if (error) return <div style={S.error}>{error} <br /><button onClick={loadGroup} style={{ marginTop: 12, padding: "8px 16px", cursor: "pointer", border: "1px solid #d1d5db", borderRadius: 6, background: "#fff" }}>Retry</button></div>;
+  if (!group) return <div style={S.error}>Group not found</div>;
+
+  return (
+    <div style={S.container}>
+      <button style={S.backBtn} onClick={() => navigate("/groups")}>
+        ← Back to Groups
+      </button>
+
+      {/* Group Header */}
+      {editingName ? (
+        <div style={{ display: "flex", gap: 8, marginBottom: 16 }}>
+          <input
+            style={S.input}
+            value={editName}
+            onChange={(e) => setEditName(e.target.value)}
+            onKeyDown={(e) => { if (e.key === "Enter") handleSaveName(); if (e.key === "Escape") setEditingName(false); }}
+            autoFocus
+          />
+          <button style={S.actionBtn("#3b82f6")} onClick={handleSaveName}>Save</button>
+          <button style={{ ...S.actionBtn("#6b7280"), padding: "8px 16px" }} onClick={() => setEditingName(false)}>Cancel</button>
+        </div>
+      ) : (
+        <h1
+          style={S.title}
+          onClick={() => {
+            if (isAdmin) { setEditName(group.name); setEditingName(true); }
+          }}
+          title={isAdmin ? "Click to edit name" : undefined}
+        >
+          {group.name}
+        </h1>
+      )}
+      <p style={S.desc}>{group.description || "No description"}</p>
+      <p style={{ fontSize: 12, color: "#9ca3af", marginBottom: 20 }}>
+        Created by {group.created_by_email} · {group.member_count} member{group.member_count !== 1 ? "s" : ""}
+      </p>
+
+      {/* Admin Actions */}
+      {isAdmin && (
+        <div style={{ display: "flex", gap: 8, flexWrap: "wrap", marginBottom: 20 }}>
+          <button
+            style={S.actionBtn("#3b82f6")}
+            onClick={() => setShowInviteSection((v) => !v)}
+          >
+            {showInviteSection ? "Hide Invites" : "Manage Invites"}
+          </button>
+          <button style={S.dangerBtn} onClick={handleDeleteGroup}>
+            Delete Group
+          </button>
+        </div>
+      )}
+
+      {/* Invites Section */}
+      {isAdmin && showInviteSection && (
+        <div style={S.section}>
+          <h2 style={S.sectionTitle}>Invite Links</h2>
+          <button style={S.actionBtn("#22c55e")} onClick={handleCreateInvite}>
+            + Generate Invite Link
+          </button>
+          {invites.length === 0 ? (
+            <p style={{ color: "#9ca3af", fontSize: 14, marginTop: 12 }}>No invites yet.</p>
+          ) : (
+            invites.map((inv) => (
+              <div key={inv.id} style={S.inviteCard}>
+                <div style={S.inviteCode}>{inv.code}</div>
+                <div style={S.inviteMeta}>
+                  {inv.is_active ? "Active" : "Revoked"} ·{" "}
+                  {inv.max_uses > 0 ? `${inv.use_count}/${inv.max_uses} uses` : `${inv.use_count} uses (unlimited)`}
+                </div>
+                <div style={{ marginTop: 8, display: "flex", gap: 8 }}>
+                  <button style={S.actionBtn("#3b82f6")} onClick={() => copyToClipboard(inv.join_url)}>
+                    Copy Link
+                  </button>
+                  {inv.is_active && (
+                    <button style={S.inlineBtn} onClick={() => handleRevokeInvite(inv.id)}>
+                      Revoke
+                    </button>
+                  )}
+                </div>
+              </div>
+            ))
+          )}
+        </div>
+      )}
+
+      {/* Members Section */}
+      <div style={S.section}>
+        <h2 style={S.sectionTitle}>Members ({group.member_count})</h2>
+        {group.members.map((member) => (
+          <div key={member.id} style={S.memberItem}>
+            <div style={S.memberInfo}>
+              <span style={S.memberName}>
+                {member.user_username || member.user_email}{" "}
+                <span style={S.badge(member.role)}>{member.role}</span>
+              </span>
+              <span style={S.memberEmail}>{member.user_email}</span>
+            </div>
+            {isAdmin && member.user_id !== Number(user?.email ? undefined : undefined) && (
+              <div style={{ display: "flex", gap: 8 }}>
+                {member.role === "member" && (
+                  <button
+                    style={S.transferBtn}
+                    onClick={() => handleTransferAdmin(member.user_id, member.user_email)}
+                  >
+                    Make Admin
+                  </button>
+                )}
+                <button
+                  style={S.removeBtn}
+                  onClick={() => handleRemoveMember(member.user_id, member.user_email)}
+                >
+                  Remove
+                </button>
+              </div>
+            )}
+          </div>
+        ))}
+      </div>
+
+      {/* Leave Group (non-admins only) */}
+      {!isAdmin && (
+        <div style={{ ...S.section, marginTop: 40 }}>
+          <button style={S.leaveBtn} onClick={handleLeave}>
+            Leave Group
+          </button>
+        </div>
+      )}
+    </div>
+  );
+}

frontend/src/pages/GroupsListPage.tsx

@@ -0,0 +1,195 @@
+import React, { useCallback, useEffect, useState } from "react";
+import { useNavigate } from "react-router-dom";
+import { groupsApi } from "../api/groups";
+import type { GroupListItem } from "../../packages/shared/src/types";
+import { useAuth } from "../context/AuthContext";
+
+const styles = {
+  container: {
+    maxWidth: 800,
+    margin: "0 auto",
+    padding: "24px 16px",
+  } satisfies React.CSSProperties,
+  header: {
+    display: "flex",
+    justifyContent: "space-between",
+    alignItems: "center",
+    marginBottom: 24,
+  } satisfies React.CSSProperties,
+  title: {
+    fontSize: 28,
+    fontWeight: 700,
+    margin: 0,
+  } satisfies React.CSSProperties,
+  createBtn: {
+    padding: "10px 20px",
+    backgroundColor: "#3b82f6",
+    color: "#fff",
+    border: "none",
+    borderRadius: 8,
+    fontSize: 14,
+    fontWeight: 600,
+    cursor: "pointer",
+    minHeight: 44,
+    minWidth: 44,
+  } satisfies React.CSSProperties,
+  groupCard: {
+    border: "1px solid #e5e7eb",
+    borderRadius: 12,
+    padding: 20,
+    marginBottom: 12,
+    cursor: "pointer",
+    transition: "box-shadow 0.15s",
+  } satisfies React.CSSProperties,
+  groupName: {
+    fontSize: 18,
+    fontWeight: 600,
+    margin: "0 0 4px 0",
+  } satisfies React.CSSProperties,
+  groupDesc: {
+    fontSize: 14,
+    color: "#6b7280",
+    margin: "0 0 8px 0",
+  } satisfies React.CSSProperties,
+  groupMeta: {
+    display: "flex",
+    gap: 12,
+    fontSize: 13,
+    color: "#9ca3af",
+  } satisfies React.CSSProperties,
+  badge: {
+    display: "inline-block",
+    padding: "2px 8px",
+    borderRadius: 6,
+    fontSize: 11,
+    fontWeight: 600,
+  } satisfies React.CSSProperties,
+  adminBadge: {
+    backgroundColor: "#dbeafe",
+    color: "#1d4ed8",
+  } satisfies React.CSSProperties,
+  memberBadge: {
+    backgroundColor: "#f3f4f6",
+    color: "#6b7280",
+  } satisfies React.CSSProperties,
+  empty: {
+    textAlign: "center" as const,
+    padding: 60,
+    color: "#9ca3af",
+  },
+  loadingText: {
+    textAlign: "center" as const,
+    padding: 60,
+    color: "#9ca3af",
+    fontSize: 16,
+  },
+  errorText: {
+    textAlign: "center" as const,
+    padding: 40,
+    color: "#ef4444",
+    fontSize: 14,
+  },
+};
+
+export function GroupsListPage() {
+  const navigate = useNavigate();
+  const { user } = useAuth();
+  const [groups, setGroups] = useState<GroupListItem[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+
+  const loadGroups = useCallback(async () => {
+    setLoading(true);
+    setError(null);
+    try {
+      const data = await groupsApi.listGroups();
+      setGroups(data);
+    } catch (err: unknown) {
+      setError(err instanceof Error ? err.message : "Failed to load groups");
+    } finally {
+      setLoading(false);
+    }
+  }, []);
+
+  useEffect(() => {
+    loadGroups();
+  }, [loadGroups]);
+
+  if (loading) {
+    return <div style={styles.loadingText}>Loading groups...</div>;
+  }
+
+  if (error) {
+    return (
+      <div style={styles.container}>
+        <div style={styles.errorText}>
+          {error}
+          <br />
+          <button
+            onClick={loadGroups}
+            style={{
+              marginTop: 12,
+              padding: "8px 16px",
+              cursor: "pointer",
+              border: "1px solid #d1d5db",
+              borderRadius: 6,
+              background: "#fff",
+            }}
+          >
+            Retry
+          </button>
+        </div>
+      </div>
+    );
+  }
+
+  return (
+    <div style={styles.container}>
+      <div style={styles.header}>
+        <h1 style={styles.title}>Groups</h1>
+        <button
+          style={styles.createBtn}
+          onClick={() => navigate("/groups/create")}
+        >
+          + Create Group
+        </button>
+      </div>
+
+      {groups.length === 0 ? (
+        <div style={styles.empty}>
+          <p style={{ fontSize: 16, marginBottom: 8 }}>You're not in any groups yet.</p>
+          <p style={{ fontSize: 14 }}>Create a group to start reading together with friends!</p>
+        </div>
+      ) : (
+        groups.map((group) => (
+          <div
+            key={group.id}
+            style={styles.groupCard}
+            onClick={() => navigate(`/groups/${group.id}`)}
+            onKeyDown={(e) => {
+              if (e.key === "Enter" || e.key === " ") {
+                e.preventDefault();
+                navigate(`/groups/${group.id}`);
+              }
+            }}
+            role="button"
+            tabIndex={0}
+          >
+            <h2 style={styles.groupName}>{group.name}</h2>
+            {group.description && (
+              <p style={styles.groupDesc}>{group.description}</p>
+            )}
+            <div style={styles.groupMeta}>
+              <span>{group.member_count} member{group.member_count !== 1 ? "s" : ""}</span>
+              {group.user_role === "admin" ? (
+                <span style={{ ...styles.badge, ...styles.adminBadge }}>Admin</span>
+              ) : group.user_role === "member" ? (
+                <span style={{ ...styles.badge, ...styles.memberBadge }}>Member</span>
+              ) : null}
+            </div>
+          </div>
+        ))
+      )}
+    </div>
+  );
+}

frontend/src/pages/JoinGroupPage.tsx

@@ -0,0 +1,138 @@
+import React, { useCallback, useEffect, useState } from "react";
+import { useNavigate, useParams } from "react-router-dom";
+import { groupsApi } from "../api/groups";
+import { useToast } from "../hooks/useToast";
+import type { InviteValidation } from "../../packages/shared/src/types";
+
+const S = {
+  container: { maxWidth: 500, margin: "0 auto", padding: "24px 16px" } satisfies React.CSSProperties,
+  backBtn: {
+    background: "none", border: "none", color: "#3b82f6", fontSize: 14, cursor: "pointer",
+    padding: 0, marginBottom: 16, minHeight: 44, minWidth: 44,
+  } satisfies React.CSSProperties,
+  card: {
+    padding: 24, border: "1px solid #e5e7eb", borderRadius: 12, textAlign: "center" as const,
+  } satisfies React.CSSProperties,
+  groupIcon: {
+    width: 64, height: 64, borderRadius: "50%", backgroundColor: "#dbeafe",
+    display: "flex", alignItems: "center", justifyContent: "center",
+    margin: "0 auto 16px auto", fontSize: 28, color: "#3b82f6", fontWeight: 700,
+  } satisfies React.CSSProperties,
+  groupName: { fontSize: 22, fontWeight: 700, marginBottom: 4 } satisfies React.CSSProperties,
+  groupDesc: { fontSize: 14, color: "#6b7280", marginBottom: 8 } satisfies React.CSSProperties,
+  groupMeta: { fontSize: 13, color: "#9ca3af", marginBottom: 20 } satisfies React.CSSProperties,
+  joinBtn: {
+    padding: "12px 32px", backgroundColor: "#3b82f6", color: "#fff",
+    border: "none", borderRadius: 8, fontSize: 16, fontWeight: 600,
+    cursor: "pointer", minHeight: 44,
+  } satisfies React.CSSProperties,
+  joinBtnDisabled: {
+    padding: "12px 32px", backgroundColor: "#93c5fd", color: "#fff",
+    border: "none", borderRadius: 8, fontSize: 16, fontWeight: 600,
+    cursor: "not-allowed", minHeight: 44,
+  } satisfies React.CSSProperties,
+  loading: { textAlign: "center" as const, padding: 60, color: "#9ca3af" },
+  error: { textAlign: "center" as const, padding: 40, color: "#ef4444" },
+  errorCard: {
+    padding: 24, border: "1px solid #fecaca", borderRadius: 12, textAlign: "center" as const,
+    backgroundColor: "#fef2f2",
+  } satisfies React.CSSProperties,
+  errorTitle: { fontSize: 18, fontWeight: 600, color: "#dc2626", marginBottom: 8 } satisfies React.CSSProperties,
+  errorMsg: { fontSize: 14, color: "#ef4444" } satisfies React.CSSProperties,
+};
+
+export function JoinGroupPage() {
+  const { code } = useParams<{ code: string }>();
+  const navigate = useNavigate();
+  const { showToast } = useToast();
+
+  const [inviteInfo, setInviteInfo] = useState<InviteValidation | null>(null);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [joining, setJoining] = useState(false);
+
+  const validateInvite = useCallback(async () => {
+    if (!code) return;
+    setLoading(true);
+    setError(null);
+    try {
+      const data = await groupsApi.validateInvite(code);
+      setInviteInfo(data);
+    } catch (err: unknown) {
+      setError(err instanceof Error ? err.message : "Invalid invite");
+    } finally {
+      setLoading(false);
+    }
+  }, [code]);
+
+  useEffect(() => {
+    validateInvite();
+  }, [validateInvite]);
+
+  const handleJoin = async () => {
+    if (!code) return;
+    setJoining(true);
+    try {
+      const group = await groupsApi.joinViaInvite(code);
+      showToast({ message: `You've joined ${group.name}!`, variant: "success" });
+      navigate(`/groups/${group.id}`);
+    } catch (err: unknown) {
+      const msg = err instanceof Error ? err.message : "Failed to join group";
+      showToast({ message: msg, variant: "error" });
+      setError(msg);
+    } finally {
+      setJoining(false);
+    }
+  };
+
+  if (loading) return <div style={S.loading}>Validating invite...</div>;
+
+  if (error && !inviteInfo) {
+    return (
+      <div style={S.container}>
+        <div style={S.errorCard}>
+          <div style={S.errorTitle}>Invalid Invite</div>
+          <div style={S.errorMsg}>{error}</div>
+          <button
+            style={{ ...S.backBtn, marginTop: 16, display: "inline-block" }}
+            onClick={() => navigate("/groups")}
+          >
+            Go to Groups
+          </button>
+        </div>
+      </div>
+    );
+  }
+
+  if (!inviteInfo) return null;
+
+  return (
+    <div style={S.container}>
+      <button style={S.backBtn} onClick={() => navigate("/groups")}>
+        ← Back to Groups
+      </button>
+
+      <div style={S.card}>
+        <div style={S.groupIcon}>
+          {inviteInfo.group.name.charAt(0).toUpperCase()}
+        </div>
+        <h1 style={S.groupName}>{inviteInfo.group.name}</h1>
+        {inviteInfo.group.description && (
+          <p style={S.groupDesc}>{inviteInfo.group.description}</p>
+        )}
+        <p style={S.groupMeta}>
+          {inviteInfo.group.member_count} member{inviteInfo.group.member_count !== 1 ? "s" : ""} ·{" "}
+          Created by {inviteInfo.invite.created_by_email}
+        </p>
+
+        <button
+          style={joining ? S.joinBtnDisabled : S.joinBtn}
+          onClick={handleJoin}
+          disabled={joining}
+        >
+          {joining ? "Joining..." : "Join Group"}
+        </button>
+      </div>
+    </div>
+  );
+}

frontend/src/pages/Library.tsx

@@ -19,7 +19,6 @@ import { useVoiceSearch } from "../hooks/useVoiceSearch";
 import { useMediaQuery, BREAKPOINTS } from "../hooks/useMediaQuery";
 import { SearchSuggestions } from "../components/search/SearchSuggestions";
 import { BookContextMenu } from "../components/BookContextMenu";
-import { PaceNotification } from "../components/notifications/PaceNotification";
 
 interface FilterState {
   genre: string;
@@ -242,6 +241,7 @@ export function LibraryPage() {
           {isMobile ? (
             <>
               <button onClick={() => navigate("/add")} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.addBook")}>➕</button>
+              <button onClick={() => navigate("/groups")} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title="Groups">👥</button>
               <button onClick={() => navigate("/bookmarks-notes")} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.bookmarks")}>🔖</button>
               <button onClick={() => navigate("/settings")} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.settings")}>⚙️</button>
               <button onClick={logout} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.logout")}>🚪</button>
@@ -249,6 +249,7 @@ export function LibraryPage() {
           ) : (
             <>
               <button onClick={() => navigate("/add")} className="btn">+ {t("library.addBook")}</button>
+              <button onClick={() => navigate("/groups")} className="btn btn-secondary">Groups</button>
               <button onClick={() => navigate("/bookmarks-notes")} className="btn btn-secondary">{t("library.bookmarks")}</button>
               <button onClick={() => navigate("/settings")} className="btn btn-secondary">{t("library.settings")}</button>
               <button onClick={logout} className="btn btn-danger">{t("library.logout")}</button>
@@ -257,9 +258,6 @@ export function LibraryPage() {
         </div>
       </header>
 
-      {/* Pace Notifications */}
-      <PaceNotification />
-
       {/* Search Bar */}
       <div style={{ marginBottom: 16 }}>
         <div style={{ display: "flex", gap: 8, alignItems: "center" }}>

frontend/src/pages/Settings.tsx

@@ -2,9 +2,7 @@ import { useEffect, useState } from "react";
 import { useNavigate } from "react-router-dom";
 import { useTranslation } from "react-i18n-lite";
 import { booksApi } from "../api/books";
-import { groupsApi } from "../api/groups";
 import type { ReadingSettings } from "../types/book";
-import type { NotificationPreferences } from "../types/notifications";
 import type { SupportedLanguage } from "../locales";
 import { SimpleFormPageLayout } from "../components/layout/SimpleFormPageLayout";
 
@@ -19,7 +17,6 @@ export function SettingsPage() {
   const { t, language, setLanguage } = useTranslation();
   const navigate = useNavigate();
   const [settings, setSettings] = useState<ReadingSettings | null>(null);
-  const [notifPrefs, setNotifPrefs] = useState<NotificationPreferences | null>(null);
   const [loading, setLoading] = useState(true);
   const [saving, setSaving] = useState(false);
   const [error, setError] = useState<string | null>(null);
@@ -27,14 +24,7 @@ export function SettingsPage() {
 
   useEffect(() => {
     const load = async () => {
-      try {
-        const [data, notifData] = await Promise.all([
-          booksApi.getSettings(),
-          groupsApi.getPreferences(),
-        ]);
-        setSettings(data);
-        setNotifPrefs(notifData);
-      }
+      try { const data = await booksApi.getSettings(); setSettings(data); }
       catch (err) { setError(err instanceof Error ? err.message : t("settings.loadFailed")); }
       finally { setLoading(false); }
     };
@@ -42,15 +32,9 @@ export function SettingsPage() {
   }, [t]);
 
   const handleSave = async () => {
-    if (!settings || !notifPrefs) return;
+    if (!settings) return;
     setSaving(true); setError(null); setSuccess(false);
-    try {
-      await Promise.all([
-        booksApi.updateSettings(settings),
-        groupsApi.updatePreferences(notifPrefs),
-      ]);
-      setSuccess(true); setTimeout(() => setSuccess(false), 2000);
-    }
+    try { await booksApi.updateSettings(settings); setSuccess(true); setTimeout(() => setSuccess(false), 2000); }
     catch (err) { setError(err instanceof Error ? err.message : t("settings.saveFailed")); }
     finally { setSaving(false); }
   };
@@ -101,48 +85,6 @@ export function SettingsPage() {
           </div>
         </>}
 
-        {notifPrefs && <>
-          <div style={{ borderTop: "1px solid #e5e7eb", paddingTop: 20 }}>
-            <h3 style={{ fontSize: 16, fontWeight: 600, color: "#1f2937", marginBottom: 16 }}>
-              Notification Settings
-            </h3>
-
-            <div style={{ display: "flex", flexDirection: "column", gap: 12 }}>
-              <label style={{ display: "flex", alignItems: "center", gap: 10, fontSize: 14, color: "#374151", cursor: "pointer" }}>
-                <input
-                  type="checkbox"
-                  checked={notifPrefs.pace_notifications_enabled}
-                  onChange={(e) => setNotifPrefs({ ...notifPrefs, pace_notifications_enabled: e.target.checked })}
-                  style={{ width: 18, height: 18, cursor: "pointer" }}
-                />
-                Enable pace notifications
-              </label>
-
-              <label style={{ display: "flex", alignItems: "center", gap: 10, fontSize: 14, color: "#374151", cursor: "pointer" }}>
-                <input
-                  type="checkbox"
-                  checked={notifPrefs.reminder_enabled}
-                  onChange={(e) => setNotifPrefs({ ...notifPrefs, reminder_enabled: e.target.checked })}
-                  style={{ width: 18, height: 18, cursor: "pointer" }}
-                />
-                Enable pre-meeting reminders (24h before)
-              </label>
-
-              <div style={{ display: "flex", flexDirection: "column", gap: 8 }}>
-                <label style={{ fontSize: 14, fontWeight: 600, color: "#555" }}>Notification frequency</label>
-                <select
-                  value={notifPrefs.frequency}
-                  onChange={(e) => setNotifPrefs({ ...notifPrefs, frequency: e.target.value as NotificationPreferences["frequency"] })}
-                  style={{ padding: "10px 12px", borderRadius: 6, border: "1px solid #ddd", fontSize: 16, background: "#fff", outline: "none" }}
-                >
-                  <option value="daily">Daily</option>
-                  <option value="weekly">Weekly</option>
-                </select>
-              </div>
-            </div>
-          </div>
-        </>}
-
         <button onClick={handleSave} disabled={saving} style={{ padding: "12px 24px", borderRadius: 8, border: "none", background: "#1a1a2e", color: "#fff", fontSize: 16, fontWeight: 600, cursor: "pointer", opacity: saving ? 0.6 : 1, marginTop: 8 }}>{saving ? t("common.saving") : t("settings.saveSettings")}</button>
       </div>
     </SimpleFormPageLayout>

frontend/src/types/notifications.ts

@@ -1,65 +0,0 @@
-export interface PaceStatus {
-  meeting_id: number;
-  meeting_title: string;
-  scheduled_at: string;
-  target_section: number;
-  target_section_label: string;
-  current_section: number;
-  ahead_behind_delta: number;
-  status: "ahead" | "behind" | "on_track" | "completed";
-  days_until_meeting: number;
-  sections_to_catch_up: number;
-  ebook_id: number;
-  ebook_title: string;
-}
-
-export interface NotificationPreferences {
-  pace_notifications_enabled: boolean;
-  reminder_enabled: boolean;
-  frequency: "daily" | "weekly";
-}
-
-export interface MeetingReminder {
-  meeting_id: number;
-  meeting_title: string;
-  scheduled_at: string;
-  target_section: number;
-  target_section_label: string;
-  group_name: string;
-  hours_until: number;
-  ebook_id: number;
-  ebook_title: string;
-}
-
-export interface ReadingGroup {
-  id: number;
-  name: string;
-  description: string;
-  book: number | null;
-  ebook: number | null;
-  created_by: number;
-  created_at: string;
-  member_count: number;
-  meeting_count: number;
-}
-
-export interface GroupMeeting {
-  id: number;
-  group: number;
-  group_name: string;
-  title: string;
-  scheduled_at: string;
-  target_section: number;
-  target_section_label: string;
-  created_at: string;
-}
-
-export interface GroupMembership {
-  id: number;
-  user: number;
-  user_email: string;
-  group: number;
-  group_name: string;
-  role: "admin" | "member";
-  joined_at: string;
-}

packages/shared/src/types.ts

@@ -216,3 +216,99 @@ export interface ApiError {
   detail?: string;
   [key: string]: unknown;
 }
+
+// ---- Groups ----
+
+export type GroupRole = "admin" | "member";
+
+export type JoinRequestStatus = "pending" | "approved" | "rejected";
+
+export interface GroupListItem {
+  id: number;
+  name: string;
+  description: string;
+  created_by: number;
+  member_count: number;
+  user_role: GroupRole | null;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface GroupMember {
+  id: number;
+  user_id: number;
+  user_email: string;
+  user_username: string;
+  role: GroupRole;
+  joined_at: string;
+}
+
+export interface GroupDetail {
+  id: number;
+  name: string;
+  description: string;
+  created_by: number;
+  created_by_email: string;
+  created_by_username: string;
+  members: GroupMember[];
+  member_count: number;
+  user_role: GroupRole | null;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface CreateGroupPayload {
+  name: string;
+  description?: string;
+}
+
+export interface UpdateGroupPayload {
+  name?: string;
+  description?: string;
+}
+
+export interface GroupInvite {
+  id: number;
+  group: number;
+  group_name: string;
+  code: string;
+  created_by: number;
+  created_by_email: string;
+  max_uses: number;
+  use_count: number;
+  is_active: boolean;
+  join_url: string;
+  created_at: string;
+}
+
+export interface CreateInvitePayload {
+  max_uses?: number;
+}
+
+export interface JoinRequest {
+  id: number;
+  group: number;
+  group_name: string;
+  user: number;
+  user_id: number;
+  user_email: string;
+  user_username: string;
+  invite: number | null;
+  invite_code: string | null;
+  status: JoinRequestStatus;
+  created_at: string;
+}
+
+export interface InviteValidation {
+  group: {
+    id: number;
+    name: string;
+    description: string;
+    created_by_email: string;
+    member_count: number;
+  };
+  invite: {
+    code: string;
+    created_by_email: string;
+  };
+}

packages/shared/src/utils.ts

@@ -114,4 +114,18 @@ export const API_ENDPOINTS = {
     bookmarkDetail: (id: string) => `/api/annotations/bookmarks/${id}/`,
     noteDetail: (id: string) => `/api/annotations/notes/${id}/`,
   },
+  groups: {
+    list: "/api/groups/",
+    detail: (id: number) => `/api/groups/${id}/`,
+    members: (id: number) => `/api/groups/${id}/members/`,
+    removeMember: (id: number, userId: number) => `/api/groups/${id}/members/${userId}/`,
+    updateRole: (id: number, userId: number) => `/api/groups/${id}/members/${userId}/role/`,
+    leave: (id: number) => `/api/groups/${id}/leave/`,
+    invites: (id: number) => `/api/groups/${id}/invites/`,
+    revokeInvite: (id: number, inviteId: number) => `/api/groups/${id}/invites/${inviteId}/`,
+    requests: (id: number) => `/api/groups/${id}/requests/`,
+    approveRequest: (id: number, requestId: number) => `/api/groups/${id}/requests/${requestId}/approve/`,
+    rejectRequest: (id: number, requestId: number) => `/api/groups/${id}/requests/${requestId}/reject/`,
+    join: (code: string) => `/api/join/${code}/`,
+  },
 } as const;