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

@@ -1,46 +1,30 @@
 from django.contrib import admin
 
-from apps.groups.models import (
-    GroupBook,
-    MemberProgress,
-    ReadingGroup,
-    ReadingGroupMembership,
-    ReadingSchedule,
-    Section,
-)
+from apps.groups.models import Group, GroupInvite, GroupMember, JoinRequest
 
 
-@admin.register(ReadingGroup)
-class ReadingGroupAdmin(admin.ModelAdmin):
-    list_display = ["name", "admin", "created_at"]
-    search_fields = ["name", "admin__email"]
+@admin.register(Group)
+class GroupAdmin(admin.ModelAdmin):
+    list_display = ["id", "name", "created_by", "created_at"]
+    search_fields = ["name", "created_by__email"]
 
 
-@admin.register(ReadingGroupMembership)
-class ReadingGroupMembershipAdmin(admin.ModelAdmin):
-    list_display = ["user", "group", "role", "joined_at"]
-    list_filter = ["role", "group"]
+@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(GroupBook)
-class GroupBookAdmin(admin.ModelAdmin):
-    list_display = ["title", "group", "status", "uploaded_by", "created_at"]
+@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(JoinRequest)
+class JoinRequestAdmin(admin.ModelAdmin):
+    list_display = ["id", "group", "user", "status", "created_at"]
     list_filter = ["status"]
-    search_fields = ["title", "group__name"]
-
-
-@admin.register(Section)
-class SectionAdmin(admin.ModelAdmin):
-    list_display = ["title", "group_book", "order", "estimated_reading_minutes"]
-    ordering = ["group_book", "order"]
-
-
-@admin.register(ReadingSchedule)
-class ReadingScheduleAdmin(admin.ModelAdmin):
-    list_display = ["group_book", "meeting_number", "week_date"]
-    ordering = ["group_book", "meeting_number"]
-
-
-@admin.register(MemberProgress)
-class MemberProgressAdmin(admin.ModelAdmin):
-    list_display = ["user", "group_book", "current_section", "updated_at"]
+    search_fields = ["group__name", "user__email"]

backend/apps/groups/apps.py

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

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

@@ -1,154 +1,88 @@
-# Generated by Django 5.1.7 on 2026-06-20 19:21
+# 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'),
         migrations.swappable_dependency(settings.AUTH_USER_MODEL),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='ReadingGroup',
+            name="Group",
             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)),
-                ('updated_at', models.DateTimeField(auto_now=True)),
-                ('admin', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='administered_groups', to=settings.AUTH_USER_MODEL)),
+                ("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': 'Reading Group',
-                'verbose_name_plural': 'Reading Groups',
-                'db_table': 'groups_reading_group',
-                'ordering': ['-created_at'],
+                "db_table": "groups_group",
+                "verbose_name": "Group",
+                "verbose_name_plural": "Groups",
+                "ordering": ["-created_at"],
             },
         ),
         migrations.CreateModel(
-            name='GroupBook',
+            name="GroupMember",
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('title', models.CharField(db_index=True, max_length=512)),
-                ('status', models.CharField(choices=[('active', 'Active'), ('replaced', 'Replaced')], db_index=True, default='active', max_length=16)),
-                ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('updated_at', models.DateTimeField(auto_now=True)),
-                ('ebook', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='group_books', to='books.ebook')),
-                ('uploaded_by', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='uploaded_group_books', to=settings.AUTH_USER_MODEL)),
-                ('group', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='group_books', to='groups.readinggroup')),
+                ("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': 'Group Book',
-                'verbose_name_plural': 'Group Books',
-                'db_table': 'groups_group_book',
-                '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='ReadingGroupMembership',
+            name="GroupInvite",
             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)),
-                ('group', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='memberships', to='groups.readinggroup')),
-                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+                ("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': 'Reading Group Membership',
-                'verbose_name_plural': 'Reading Group Memberships',
-                'db_table': 'groups_membership',
-            },
-        ),
-        migrations.AddField(
-            model_name='readinggroup',
-            name='members',
-            field=models.ManyToManyField(related_name='reading_groups', through='groups.ReadingGroupMembership', to=settings.AUTH_USER_MODEL),
-        ),
-        migrations.CreateModel(
-            name='ReadingSchedule',
-            fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('meeting_number', models.PositiveIntegerField()),
-                ('week_date', models.DateField()),
-                ('section_ids', models.JSONField(default=list, help_text='Ordered list of Section IDs for this meeting')),
-                ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('group_book', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='schedules', to='groups.groupbook')),
-            ],
-            options={
-                'verbose_name': 'Reading Schedule',
-                'verbose_name_plural': 'Reading Schedules',
-                'db_table': 'groups_reading_schedule',
-                'ordering': ['meeting_number'],
+                "db_table": "groups_invite",
+                "verbose_name": "Group Invite",
+                "verbose_name_plural": "Group Invites",
+                "ordering": ["-created_at"],
             },
         ),
         migrations.CreateModel(
-            name='Section',
+            name="JoinRequest",
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('title', models.CharField(max_length=512)),
-                ('order', models.PositiveIntegerField(db_index=True)),
-                ('start_chapter_index', models.PositiveIntegerField(default=0)),
-                ('end_chapter_index', models.PositiveIntegerField(default=0)),
-                ('estimated_reading_minutes', models.PositiveIntegerField(default=0)),
-                ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('group_book', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='sections', to='groups.groupbook')),
+                ("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': 'Section',
-                'verbose_name_plural': 'Sections',
-                'db_table': 'groups_section',
-                'ordering': ['order'],
+                "db_table": "groups_join_request",
+                "verbose_name": "Join Request",
+                "verbose_name_plural": "Join Requests",
+                "ordering": ["-created_at"],
+                "unique_together": {("group", "user")},
             },
         ),
-        migrations.CreateModel(
-            name='MemberProgress',
-            fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('completed_sections', models.JSONField(default=list, help_text='Ordered list of completed Section IDs')),
-                ('updated_at', models.DateTimeField(auto_now=True)),
-                ('group_book', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='member_progress', to='groups.groupbook')),
-                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='group_progress', to=settings.AUTH_USER_MODEL)),
-                ('current_section', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='current_readers', to='groups.section')),
-            ],
-            options={
-                'verbose_name': 'Member Progress',
-                'verbose_name_plural': 'Member Progress',
-                'db_table': 'groups_member_progress',
-            },
-        ),
-        migrations.AddIndex(
-            model_name='groupbook',
-            index=models.Index(fields=['group', 'status'], name='groups_grou_group_i_afdbf7_idx'),
-        ),
-        migrations.AlterUniqueTogether(
-            name='readinggroupmembership',
-            unique_together={('user', 'group')},
-        ),
-        migrations.AddIndex(
-            model_name='readingschedule',
-            index=models.Index(fields=['group_book', 'meeting_number'], name='groups_read_group_b_2fc416_idx'),
-        ),
-        migrations.AlterUniqueTogether(
-            name='readingschedule',
-            unique_together={('group_book', 'meeting_number')},
-        ),
-        migrations.AddIndex(
-            model_name='section',
-            index=models.Index(fields=['group_book', 'order'], name='groups_sect_group_b_e2810a_idx'),
-        ),
-        migrations.AlterUniqueTogether(
-            name='section',
-            unique_together={('group_book', 'order')},
-        ),
-        migrations.AlterUniqueTogether(
-            name='memberprogress',
-            unique_together={('user', 'group_book')},
-        ),
     ]

backend/apps/groups/models.py

@@ -1,161 +1,129 @@
+import uuid
+
 from django.conf import settings
 from django.db import models
 
-from apps.books.models import EBook
+
+class GroupRole(models.TextChoices):
+    ADMIN = "admin", "Admin"
+    MEMBER = "member", "Member"
 
 
-class ReadingGroup(models.Model):
-    """A reading group with an admin and members."""
+class JoinRequestStatus(models.TextChoices):
+    PENDING = "pending", "Pending"
+    APPROVED = "approved", "Approved"
+    REJECTED = "rejected", "Rejected"
 
+
+class Group(models.Model):
     name = models.CharField(max_length=256, db_index=True)
     description = models.TextField(blank=True, default="")
-    admin = models.ForeignKey(
+    created_by = models.ForeignKey(
         settings.AUTH_USER_MODEL,
         on_delete=models.CASCADE,
-        related_name="administered_groups",
-    )
-    members = models.ManyToManyField(
-        settings.AUTH_USER_MODEL,
-        through="ReadingGroupMembership",
-        related_name="reading_groups",
+        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 ReadingGroupMembership(models.Model):
-    class Role(models.TextChoices):
-        ADMIN = "admin", "Admin"
-        MEMBER = "member", "Member"
-
-    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
-    group = models.ForeignKey(ReadingGroup, on_delete=models.CASCADE, related_name="memberships")
-    role = models.CharField(max_length=16, choices=Role.choices, default=Role.MEMBER)
+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",
+    )
+    role = models.CharField(
+        max_length=16,
+        choices=GroupRole.choices,
+        default=GroupRole.MEMBER,
+    )
     joined_at = models.DateTimeField(auto_now_add=True)
 
     class Meta:
-        db_table = "groups_membership"
-        unique_together = [("user", "group")]
-        verbose_name = "Reading Group Membership"
-        verbose_name_plural = "Reading Group Memberships"
+        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.name} ({self.role})"
+        return f"{self.user} in {self.group} ({self.role})"
 
 
-class GroupBook(models.Model):
-    """Links an uploaded EBook to a reading group."""
-
-    class Status(models.TextChoices):
-        ACTIVE = "active", "Active"
-        REPLACED = "replaced", "Replaced"
-
+class GroupInvite(models.Model):
     group = models.ForeignKey(
-        ReadingGroup, on_delete=models.CASCADE, related_name="group_books"
+        Group,
+        on_delete=models.CASCADE,
+        related_name="invites",
     )
-    ebook = models.ForeignKey(
-        EBook, on_delete=models.CASCADE, related_name="group_books"
-    )
-    uploaded_by = models.ForeignKey(
-        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="uploaded_group_books"
-    )
-    title = models.CharField(max_length=512, db_index=True)
-    status = models.CharField(
-        max_length=16, choices=Status.choices, default=Status.ACTIVE, db_index=True
+    created_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        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_group_book"
-        verbose_name = "Group Book"
-        verbose_name_plural = "Group Books"
+        db_table = "groups_invite"
+        verbose_name = "Group Invite"
+        verbose_name_plural = "Group Invites"
         ordering = ["-created_at"]
-        indexes = [models.Index(fields=["group", "status"])]
 
     def __str__(self) -> str:
-        return f"{self.group.name} — {self.title}"
+        return f"Invite for {self.group.name} ({self.code})"
 
 
-class Section(models.Model):
-    """A section/chunk of a GroupBook for group reading."""
-
-    group_book = models.ForeignKey(
-        GroupBook, on_delete=models.CASCADE, related_name="sections"
+class JoinRequest(models.Model):
+    group = models.ForeignKey(
+        Group,
+        on_delete=models.CASCADE,
+        related_name="join_requests",
     )
-    title = models.CharField(max_length=512)
-    order = models.PositiveIntegerField(db_index=True)
-    start_chapter_index = models.PositiveIntegerField(default=0)
-    end_chapter_index = models.PositiveIntegerField(default=0)
-    estimated_reading_minutes = models.PositiveIntegerField(default=0)
-    created_at = models.DateTimeField(auto_now_add=True)
-
-    class Meta:
-        db_table = "groups_section"
-        verbose_name = "Section"
-        verbose_name_plural = "Sections"
-        ordering = ["order"]
-        unique_together = [("group_book", "order")]
-        indexes = [models.Index(fields=["group_book", "order"])]
-
-    def __str__(self) -> str:
-        return f"{self.group_book.title} — Section {self.order}: {self.title}"
-
-
-class ReadingSchedule(models.Model):
-    """Reading schedule mapping sections to weekly meetings."""
-
-    group_book = models.ForeignKey(
-        GroupBook, on_delete=models.CASCADE, related_name="schedules"
-    )
-    meeting_number = models.PositiveIntegerField()
-    week_date = models.DateField()
-    section_ids = models.JSONField(default=list, help_text="Ordered list of Section IDs for this meeting")
-    created_at = models.DateTimeField(auto_now_add=True)
-
-    class Meta:
-        db_table = "groups_reading_schedule"
-        verbose_name = "Reading Schedule"
-        verbose_name_plural = "Reading Schedules"
-        ordering = ["meeting_number"]
-        unique_together = [("group_book", "meeting_number")]
-        indexes = [models.Index(fields=["group_book", "meeting_number"])]
-
-    def __str__(self) -> str:
-        return f"{self.group_book.title} — Meeting {self.meeting_number}"
-
-
-class MemberProgress(models.Model):
-    """Tracks a member's progress through sections of a group book."""
-
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="group_progress"
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        related_name="join_requests",
     )
-    group_book = models.ForeignKey(
-        GroupBook, on_delete=models.CASCADE, related_name="member_progress"
+    invite = models.ForeignKey(
+        GroupInvite,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="join_requests",
     )
-    current_section = models.ForeignKey(
-        Section, on_delete=models.SET_NULL, null=True, blank=True, related_name="current_readers"
+    status = models.CharField(
+        max_length=16,
+        choices=JoinRequestStatus.choices,
+        default=JoinRequestStatus.PENDING,
+        db_index=True,
     )
-    completed_sections = models.JSONField(
-        default=list, help_text="Ordered list of completed Section IDs"
-    )
-    updated_at = models.DateTimeField(auto_now=True)
+    created_at = models.DateTimeField(auto_now_add=True)
 
     class Meta:
-        db_table = "groups_member_progress"
-        verbose_name = "Member Progress"
-        verbose_name_plural = "Member Progress"
-        unique_together = [("user", "group_book")]
+        db_table = "groups_join_request"
+        verbose_name = "Join Request"
+        verbose_name_plural = "Join Requests"
+        ordering = ["-created_at"]
+        unique_together = [("group", "user")]
 
     def __str__(self) -> str:
-        return f"{self.user} — {self.group_book.title}"
+        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

@@ -2,184 +2,197 @@ from __future__ import annotations
 
 from rest_framework import serializers
 
-from apps.groups.models import (
-    GroupBook,
-    MemberProgress,
-    ReadingGroup,
-    ReadingGroupMembership,
-    ReadingSchedule,
-    Section,
-)
-from apps.books.serializers import EBookListSerializer
+from apps.groups.models import Group, GroupInvite, GroupMember, GroupRole, JoinRequest, JoinRequestStatus
 
 
-class ReadingGroupMembershipSerializer(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)
     user_username = serializers.CharField(source="user.username", read_only=True)
 
     class Meta:
-        model = ReadingGroupMembership
+        model = GroupMember
         fields = [
-            "id", "user", "user_email", "user_username",
+            "id", "user_id", "user_email", "user_username",
             "role", "joined_at",
         ]
-        read_only_fields = ["id", "joined_at"]
 
 
-class ReadingGroupListSerializer(serializers.ModelSerializer):
+class GroupListSerializer(serializers.ModelSerializer):
     member_count = serializers.SerializerMethodField()
-    admin_email = serializers.CharField(source="admin.email", read_only=True)
+    user_role = serializers.SerializerMethodField()
 
     class Meta:
-        model = ReadingGroup
+        model = Group
         fields = [
-            "id", "name", "description", "admin", "admin_email",
-            "member_count", "created_at", "updated_at",
+            "id", "name", "description", "created_by",
+            "member_count", "user_role", "created_at", "updated_at",
         ]
 
-    def get_member_count(self, obj: ReadingGroup) -> int:
-        return obj.memberships.count()
+    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 ReadingGroupDetailSerializer(serializers.ModelSerializer):
-    admin_email = serializers.CharField(source="admin.email", read_only=True)
-    members = ReadingGroupMembershipSerializer(source="memberships", many=True, read_only=True)
+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 = ReadingGroup
+        model = Group
         fields = [
-            "id", "name", "description", "admin", "admin_email",
-            "members", "created_at", "updated_at",
+            "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())
 
-class ReadingGroupCreateSerializer(serializers.ModelSerializer):
+    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 = ReadingGroup
+        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 AddMemberSerializer(serializers.Serializer):
-    user_id = serializers.IntegerField()
+    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
 
-    def validate_user_id(self, value: int) -> int:
-        from django.conf import settings
-        User = settings.AUTH_USER_MODEL
-        if not User.objects.filter(id=value).exists():
-            raise serializers.ValidationError("User not found.")
+
+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
 
-
-class SectionSerializer(serializers.ModelSerializer):
-    class Meta:
-        model = Section
-        fields = [
-            "id", "title", "order", "start_chapter_index",
-            "end_chapter_index", "estimated_reading_minutes", "created_at",
-        ]
-        read_only_fields = ["id", "created_at"]
+    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 SectionAdjustSerializer(serializers.Serializer):
-    """Payload for manual section adjustments (merge/split)."""
-    operation = serializers.ChoiceField(choices=["merge", "split"])
-    section_ids = serializers.ListField(
-        child=serializers.IntegerField(), min_length=1,
-        help_text="For merge: list of section IDs to merge. For split: [section_id] to split."
-    )
-    split_at = serializers.IntegerField(
-        required=False, default=2, min_value=2,
-        help_text="Number of new sections when splitting"
-    )
-
-
-class ReadingScheduleSerializer(serializers.ModelSerializer):
-    section_details = serializers.SerializerMethodField()
-
-    class Meta:
-        model = ReadingSchedule
-        fields = [
-            "id", "meeting_number", "week_date", "section_ids",
-            "section_details", "created_at",
-        ]
-        read_only_fields = ["id", "created_at"]
-
-    def get_section_details(self, obj: ReadingSchedule) -> list[dict]:
-        sections = Section.objects.filter(
-            id__in=obj.section_ids, group_book=obj.group_book
-        ).order_by("order")
-        return SectionSerializer(sections, many=True).data
-
-
-class MemberProgressSerializer(serializers.ModelSerializer):
+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)
-    current_section_title = serializers.SerializerMethodField()
+    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 = MemberProgress
+        model = JoinRequest
         fields = [
-            "id", "user", "user_email", "user_username",
-            "current_section", "current_section_title",
-            "completed_sections", "updated_at",
+            "id", "group", "group_name", "user", "user_id", "user_email",
+            "user_username", "invite", "invite_code", "status", "created_at",
         ]
-        read_only_fields = ["id", "updated_at"]
-
-    def get_current_section_title(self, obj: MemberProgress) -> str | None:
-        if obj.current_section:
-            return obj.current_section.title
-        return None
+        read_only_fields = ["id", "group", "user", "invite", "created_at"]
 
 
-class GroupBookListSerializer(serializers.ModelSerializer):
-    ebook = EBookListSerializer(read_only=True)
-    uploaded_by_email = serializers.CharField(source="uploaded_by.email", read_only=True)
-    section_count = serializers.SerializerMethodField()
+class JoinViaInviteSerializer(serializers.Serializer):
+    """Validates and processes joining a group via an invite code."""
 
-    class Meta:
-        model = GroupBook
-        fields = [
-            "id", "title", "status", "ebook", "uploaded_by",
-            "uploaded_by_email", "section_count", "created_at", "updated_at",
-        ]
+    code = serializers.UUIDField()
 
-    def get_section_count(self, obj: GroupBook) -> int:
-        return obj.sections.count()
+    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.")
 
-class GroupBookDetailSerializer(serializers.ModelSerializer):
-    ebook = EBookListSerializer(read_only=True)
-    uploaded_by_email = serializers.CharField(source="uploaded_by.email", read_only=True)
-    sections = SectionSerializer(many=True, read_only=True)
-    schedules = ReadingScheduleSerializer(source="schedules", many=True, read_only=True)
+        if invite.max_uses > 0 and invite.use_count >= invite.max_uses:
+            raise serializers.ValidationError("This invite has reached its maximum uses.")
 
-    class Meta:
-        model = GroupBook
-        fields = [
-            "id", "group", "title", "status", "ebook",
-            "uploaded_by", "uploaded_by_email",
-            "sections", "schedules", "created_at", "updated_at",
-        ]
-
-
-class GroupBookCreateSerializer(serializers.Serializer):
-    ebook_id = serializers.IntegerField()
-    title = serializers.CharField(max_length=512, required=False)
-
-    def validate_ebook_id(self, value: int) -> int:
-        from apps.books.models import EBook
-        if not EBook.objects.filter(id=value).exists():
-            raise serializers.ValidationError("EBook not found.")
-        # Check format is EPUB
-        ebook = EBook.objects.get(id=value)
-        if ebook.format != "epub":
-            raise serializers.ValidationError("Only EPUB format is supported for group books.")
         return value
 
-    def validate(self, data: dict) -> dict:
-        request = self.context.get("request")
-        if request and not data.get("title"):
-            from apps.books.models import EBook
-            ebook = EBook.objects.get(id=data["ebook_id"])
-            data["title"] = ebook.title
-        return data
+
+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/section_splitting.py

@@ -1,241 +0,0 @@
-"""Automatic section detection and meeting recommendation for group books."""
-
-from __future__ import annotations
-
-import logging
-from datetime import date, timedelta
-from typing import Any
-
-from django.db.models import QuerySet
-
-from apps.books.models import BookChapter, EBook
-from apps.groups.models import GroupBook, ReadingSchedule, Section
-
-logger = logging.getLogger(__name__)
-
-WORDS_PER_MINUTE = 250  # Average reading speed
-
-
-def _fetch_chapter_text(ebook: EBook, chapter: BookChapter) -> str:
-    """Extract plain text from a chapter for word counting."""
-    try:
-        from ebooklib import epub
-        from bs4 import BeautifulSoup
-    except ImportError:
-        return ""
-
-    try:
-        book = epub.read_epub(ebook.file.path)
-        href = chapter.href or ""
-        for item in book.get_items():
-            item_name = item.get_name() or ""
-            if href and (item_name.endswith(href) or href.endswith(item_name)):
-                content = item.get_content()
-                soup = BeautifulSoup(content, "html.parser")
-                body = soup.find("body")
-                if body:
-                    return body.get_text(separator=" ", strip=True)
-                return soup.get_text(separator=" ", strip=True)
-        return ""
-    except Exception:
-        logger.exception("Failed to extract text for chapter %s", chapter.id)
-        return ""
-
-
-def _estimate_reading_minutes(text: str) -> int:
-    """Estimate reading time based on word count at WORDS_PER_MINUTE."""
-    word_count = len(text.split())
-    if word_count == 0:
-        return 1
-    return max(1, round(word_count / WORDS_PER_MINUTE))
-
-
-def detect_sections(group_book: GroupBook) -> list[dict[str, Any]]:
-    """Auto-detect sections from a GroupBook's chapters.
-
-    Groups consecutive chapters into logical sections based on TOC structure.
-    Top-level TOC entries become sections; if there are very few (< 3),
-    groups of ~5 chapters become sections instead.
-    """
-    ebook = group_book.ebook
-    chapters = list(
-        BookChapter.objects.filter(ebook=ebook).order_by("index").select_related("ebook")
-    )
-
-    if not chapters:
-        return []
-
-    top_level = [ch for ch in chapters if not ch.children or len(ch.children) == 0]
-    has_children = [ch for ch in chapters if ch.children and len(ch.children) > 0]
-
-    sections: list[dict[str, Any]] = []
-
-    if len(has_children) >= 3:
-        # Use TOC structure: each top-level chapter (with children) is a section
-        for idx, ch in enumerate(has_children):
-            # Find all child chapters belonging to this parent
-            child_indices = _collect_child_indices(chapters, ch, idx)
-            start_idx = ch.index
-            end_idx = child_indices[-1] if child_indices else start_idx
-
-            section_chapters = [c for c in chapters if start_idx <= c.index <= end_idx]
-            total_text = ""
-            for sc in section_chapters:
-                total_text += " " + _fetch_chapter_text(ebook, sc)
-
-            sections.append({
-                "title": ch.title,
-                "order": idx + 1,
-                "start_chapter_index": start_idx,
-                "end_chapter_index": end_idx + 1,
-                "estimated_reading_minutes": _estimate_reading_minutes(total_text),
-            })
-    else:
-        # Group chapters into chunks of ~5
-        chunk_size = max(1, len(top_level) // 6 if len(top_level) > 6 else 5)
-        chunk_size = max(3, min(chunk_size, 10))
-
-        group_start = 0
-        section_order = 1
-        total = len(top_level) or len(chapters)
-        source = top_level or chapters
-
-        while group_start < total:
-            group_end = min(group_start + chunk_size, total)
-            chunk = source[group_start:group_end]
-
-            total_text = ""
-            for ch in chunk:
-                total_text += " " + _fetch_chapter_text(ebook, ch)
-
-            first_title = chunk[0].title if chunk else "Section"
-            last_title = chunk[-1].title if len(chunk) > 1 else ""
-            title = f"{first_title}" if not last_title or first_title == last_title else f"{first_title} — {last_title}"
-
-            sections.append({
-                "title": title,
-                "order": section_order,
-                "start_chapter_index": chunk[0].index,
-                "end_chapter_index": chunk[-1].index + 1,
-                "estimated_reading_minutes": _estimate_reading_minutes(total_text),
-            })
-            group_start = group_end
-            section_order += 1
-
-    return sections
-
-
-def _collect_child_indices(chapters: list[BookChapter], parent: BookChapter, parent_idx: int) -> list[int]:
-    """Collect indices of all chapters that are children of the given parent TOC entry."""
-    indices: list[int] = [parent.index]
-    child_hrefs: set[str] = set()
-    for child in parent.children:
-        if isinstance(child, dict):
-            child_hrefs.add(child.get("href", ""))
-        elif hasattr(child, "href"):
-            child_hrefs.add(getattr(child, "href", ""))
-
-    for ch in chapters:
-        if ch.index == parent.index:
-            continue
-        if ch.href in child_hrefs or any(
-            ch.href.endswith(h) or h.endswith(ch.href) for h in child_hrefs
-        ):
-            indices.append(ch.index)
-
-    # Also include chapters between this parent and the next parent
-    if parent_idx + 1 < len(chapters):
-        next_parent = chapters[parent_idx + 1]
-        for ch in chapters:
-            if parent.index < ch.index < next_parent.index:
-                indices.append(ch.index)
-
-    return sorted(set(indices))
-
-
-def apply_sections(group_book: GroupBook) -> list[Section]:
-    """Detect sections and persist them to the database, replacing existing ones."""
-    Section.objects.filter(group_book=group_book).delete()
-    sections_data = detect_sections(group_book)
-    created: list[Section] = []
-    for data in sections_data:
-        section = Section.objects.create(
-            group_book=group_book,
-            title=data["title"],
-            order=data["order"],
-            start_chapter_index=data["start_chapter_index"],
-            end_chapter_index=data["end_chapter_index"],
-            estimated_reading_minutes=data["estimated_reading_minutes"],
-        )
-        created.append(section)
-    return created
-
-
-def recommend_meetings(group_book: GroupBook, num_meetings: int = 4) -> list[dict[str, Any]]:
-    """Recommend which sections to assign to each weekly meeting.
-
-    Distributes sections across meetings, trying to balance total reading time.
-    Returns a list of meeting assignments ready for schedule creation.
-    """
-    sections = list(
-        Section.objects.filter(group_book=group_book).order_by("order")
-    )
-
-    if not sections:
-        return []
-
-    # Calculate total minutes to distribute
-    total_minutes = sum(s.estimated_reading_minutes for s in sections)
-    target_per_meeting = total_minutes / num_meetings
-
-    meetings: list[dict[str, Any]] = []
-    current_meeting: list[int] = []
-    current_minutes = 0
-
-    for section in sections:
-        if current_meeting and current_minutes + section.estimated_reading_minutes > target_per_meeting * 1.4:
-            # Start new meeting if adding this section would overshoot too much
-            if len(meetings) < num_meetings - 1:
-                meetings.append({
-                    "meeting_number": len(meetings) + 1,
-                    "section_ids": current_meeting,
-                    "total_minutes": current_minutes,
-                })
-                current_meeting = []
-                current_minutes = 0
-
-        current_meeting.append(section.id)
-        current_minutes += section.estimated_reading_minutes
-
-    # Add the last meeting
-    if current_meeting:
-        meetings.append({
-            "meeting_number": len(meetings) + 1,
-            "section_ids": current_meeting,
-            "total_minutes": current_minutes,
-        })
-
-    # If we have fewer than num_meetings, we could split the largest one
-    # For now, just return what we have
-    return meetings
-
-
-def apply_schedule(group_book: GroupBook, num_meetings: int = 4) -> list[ReadingSchedule]:
-    """Generate and persist a reading schedule."""
-    ReadingSchedule.objects.filter(group_book=group_book).delete()
-
-    recommendations = recommend_meetings(group_book, num_meetings)
-    today = date.today()
-
-    created: list[ReadingSchedule] = []
-    for rec in recommendations:
-        week_date = today + timedelta(weeks=rec["meeting_number"] - 1)
-        schedule = ReadingSchedule.objects.create(
-            group_book=group_book,
-            meeting_number=rec["meeting_number"],
-            week_date=week_date,
-            section_ids=rec["section_ids"],
-        )
-        created.append(schedule)
-
-    return created

backend/apps/groups/urls.py

@@ -1,43 +1,12 @@
 from django.urls import include, path
 from rest_framework.routers import DefaultRouter
 
-from apps.groups.views import GroupBookViewSet, ReadingGroupViewSet
+from apps.groups.views import GroupViewSet, JoinGroupViewSet
 
-# ReadingGroup routes (standard ViewSet)
 router = DefaultRouter()
-router.register(r"", ReadingGroupViewSet, basename="group")
+router.register(r"groups", GroupViewSet, basename="group")
+router.register(r"join", JoinGroupViewSet, basename="join-group")
 
 urlpatterns = [
     path("", include(router.urls)),
-    # Nested GroupBook routes under a group
-    path(
-        "<int:group_pk>/books/",
-        GroupBookViewSet.as_view({"get": "list", "post": "create"}),
-        name="group-book-list",
-    ),
-    path(
-        "<int:group_pk>/books/<int:pk>/",
-        GroupBookViewSet.as_view({"get": "retrieve", "delete": "destroy"}),
-        name="group-book-detail",
-    ),
-    path(
-        "<int:group_pk>/books/<int:pk>/detect-sections/",
-        GroupBookViewSet.as_view({"post": "detect_sections_action"}),
-        name="group-book-detect-sections",
-    ),
-    path(
-        "<int:group_pk>/books/<int:pk>/adjust-sections/",
-        GroupBookViewSet.as_view({"post": "adjust_sections"}),
-        name="group-book-adjust-sections",
-    ),
-    path(
-        "<int:group_pk>/books/<int:pk>/schedule/",
-        GroupBookViewSet.as_view({"get": "schedule", "post": "schedule", "delete": "schedule"}),
-        name="group-book-schedule",
-    ),
-    path(
-        "<int:group_pk>/books/<int:pk>/progress/",
-        GroupBookViewSet.as_view({"get": "progress", "patch": "progress"}),
-        name="group-book-progress",
-    ),
 ]

backend/apps/groups/views.py

@@ -1,349 +1,331 @@
 from __future__ import annotations
 
-import logging
-from typing import Any
-
-from django.db.models import QuerySet
-from django.shortcuts import get_object_or_404
-from rest_framework import permissions, status, viewsets
+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 (
-    GroupBook,
-    MemberProgress,
-    ReadingGroup,
-    ReadingGroupMembership,
-    ReadingSchedule,
-    Section,
-)
+from apps.groups.models import Group, GroupInvite, GroupMember, GroupRole, JoinRequest, JoinRequestStatus
+from apps.groups.permissions import IsGroupAdmin, IsGroupMember
 from apps.groups.serializers import (
-    AddMemberSerializer,
-    GroupBookCreateSerializer,
-    GroupBookDetailSerializer,
-    GroupBookListSerializer,
-    MemberProgressSerializer,
-    ReadingGroupCreateSerializer,
-    ReadingGroupDetailSerializer,
-    ReadingGroupListSerializer,
-    ReadingScheduleSerializer,
-    SectionAdjustSerializer,
-    SectionSerializer,
-)
-from apps.groups.services.section_splitting import (
-    apply_schedule,
-    apply_sections,
-    detect_sections,
+    GroupCreateSerializer,
+    GroupDetailSerializer,
+    GroupInviteCreateSerializer,
+    GroupInviteSerializer,
+    GroupListSerializer,
+    GroupMemberSerializer,
+    GroupUpdateSerializer,
+    JoinRequestSerializer,
+    JoinViaInviteSerializer,
+    RoleUpdateSerializer,
 )
 
-logger = logging.getLogger(__name__)
 
-
-class IsGroupAdmin(permissions.BasePermission):
-    """Only the group admin can modify group resources."""
-
-    def has_permission(self, request: Request, view: object) -> bool:
-        if not request.user.is_authenticated:
-            return False
-        if view.action in ("list", "retrieve"):
-            return True
-        group_id = view.kwargs.get("pk") or view.kwargs.get("group_pk")
-        if group_id:
-            return ReadingGroup.objects.filter(id=group_id, admin=request.user).exists()
-        return True
-
-    def has_object_permission(self, request: Request, view: object, obj: ReadingGroup) -> bool:
-        if request.method in permissions.SAFE_METHODS:
-            return True
-        return obj.admin == request.user
-
-
-class IsGroupMember(permissions.BasePermission):
-    """Only group members (including admin) can view group content."""
-
-    def has_permission(self, request: Request, view: object) -> bool:
-        if not request.user.is_authenticated:
-            return False
-        group_id = view.kwargs.get("pk") or view.kwargs.get("group_pk")
-        if group_id:
-            return ReadingGroupMembership.objects.filter(
-                group_id=group_id, user=request.user
-            ).exists()
-        return True
-
-
-class ReadingGroupViewSet(viewsets.ModelViewSet):
-    permission_classes = [permissions.IsAuthenticated, IsGroupAdmin]
-    queryset = ReadingGroup.objects.prefetch_related("memberships__user")
+class GroupViewSet(viewsets.ModelViewSet):
+    permission_classes = [IsAuthenticated]
 
     def get_serializer_class(self):
         if self.action == "create":
-            return ReadingGroupCreateSerializer
+            return GroupCreateSerializer
+        if self.action in ("update", "partial_update"):
+            return GroupUpdateSerializer
         if self.action == "retrieve":
-            return ReadingGroupDetailSerializer
-        return ReadingGroupListSerializer
+            return GroupDetailSerializer
+        return GroupListSerializer
 
-    def get_queryset(self) -> QuerySet[ReadingGroup]:
+    def get_queryset(self) -> QuerySet[Group]:
         user = self.request.user
-        return ReadingGroup.objects.filter(
-            memberships__user=user
-        ).prefetch_related("memberships__user").distinct()
-
-    def perform_create(self, serializer: ReadingGroupCreateSerializer) -> ReadingGroup:
-        group = serializer.save(admin=self.request.user)
-        ReadingGroupMembership.objects.create(
-            user=self.request.user, group=group, role=ReadingGroupMembership.Role.ADMIN
-        )
-        return group
-
-    @action(detail=True, methods=["post"], permission_classes=[IsGroupAdmin])
-    def add_member(self, request: Request, pk: int | None = None) -> Response:
-        group = self.get_object()
-        member_serializer = AddMemberSerializer(data=request.data)
-        member_serializer.is_valid(raise_exception=True)
-
-        user_id = member_serializer.validated_data["user_id"]
-        from django.conf import settings
-        User = settings.AUTH_USER_MODEL
-        new_member = get_object_or_404(User, id=user_id)
-
-        if ReadingGroupMembership.objects.filter(group=group, user=new_member).exists():
-            return Response(
-                {"detail": "User is already a member of this group."},
-                status=status.HTTP_409_CONFLICT,
+        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
 
-        membership = ReadingGroupMembership.objects.create(
-            user=new_member, group=group, role=ReadingGroupMembership.Role.MEMBER
-        )
-        from apps.groups.serializers import ReadingGroupMembershipSerializer
-        return Response(
-            ReadingGroupMembershipSerializer(membership).data,
-            status=status.HTTP_201_CREATED,
-        )
+    def get_object(self) -> Group:
+        obj = super().get_object()
+        # Cache the requesting user's membership for serializers
+        try:
+            obj._user_membership = obj.memberships.get(user=self.request.user)
+        except GroupMember.DoesNotExist:
+            obj._user_membership = None
+        return obj
 
-    @action(detail=True, methods=["post"], permission_classes=[IsGroupAdmin])
-    def remove_member(self, request: Request, pk: int | None = None) -> Response:
+    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()
-        member_serializer = AddMemberSerializer(data=request.data)
-        member_serializer.is_valid(raise_exception=True)
+        memberships = group.memberships.select_related("user").order_by("joined_at")
+        serializer = GroupMemberSerializer(memberships, many=True)
+        return Response(serializer.data)
 
-        user_id = member_serializer.validated_data["user_id"]
-        if user_id == group.admin_id:
+    @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(
-                {"detail": "Cannot remove the group admin."},
+                {"error": "Admins cannot remove themselves. Use leave instead, or transfer admin first."},
                 status=status.HTTP_400_BAD_REQUEST,
             )
 
-        deleted, _ = ReadingGroupMembership.objects.filter(
-            group=group, user_id=user_id
-        ).delete()
-        if not deleted:
-            return Response(
-                {"detail": "User is not a member of this group."},
-                status=status.HTTP_404_NOT_FOUND,
-            )
+        membership.delete()
         return Response(status=status.HTTP_204_NO_CONTENT)
 
-
-class GroupBookViewSet(viewsets.ModelViewSet):
-    permission_classes = [permissions.IsAuthenticated, IsGroupAdmin]
-
-    def get_serializer_class(self):
-        if self.action == "create":
-            return GroupBookCreateSerializer
-        if self.action == "retrieve":
-            return GroupBookDetailSerializer
-        return GroupBookListSerializer
-
-    def get_queryset(self) -> QuerySet[GroupBook]:
-        group_id = self.kwargs.get("group_pk")
-        return GroupBook.objects.filter(
-            group_id=group_id
-        ).select_related("ebook", "ebook__user", "uploaded_by").prefetch_related(
-            "sections", "schedules"
-        )
-
-    def perform_create(self, serializer: GroupBookCreateSerializer) -> GroupBook:
-        group = get_object_or_404(ReadingGroup, id=self.kwargs["group_pk"])
-        ebook = get_object_or_404(EBook, id=serializer.validated_data["ebook_id"])
-        title = serializer.validated_data.get("title") or ebook.title
-
-        # Mark existing active books as replaced
-        GroupBook.objects.filter(group=group, status=GroupBook.Status.ACTIVE).update(
-            status=GroupBook.Status.REPLACED
-        )
-
-        group_book = GroupBook.objects.create(
-            group=group,
-            ebook=ebook,
-            uploaded_by=self.request.user,
-            title=title,
-            status=GroupBook.Status.ACTIVE,
-        )
-
-        # Auto-detect sections
-        try:
-            apply_sections(group_book)
-        except Exception:
-            logger.exception("Auto-section detection failed for group_book %s", group_book.id)
-
-        # Auto-generate schedule
-        try:
-            apply_schedule(group_book)
-        except Exception:
-            logger.exception("Schedule generation failed for group_book %s", group_book.id)
-
-        return group_book
-
-    @action(detail=True, methods=["post"], url_path="detect-sections")
-    def detect_sections_action(self, request: Request, group_pk: int | None = None, pk: int | None = None) -> Response:
-        group_book = self.get_object()
-        try:
-            sections = apply_sections(group_book)
-        except Exception as exc:
-            logger.exception("Section detection failed for group_book %s", group_book.id)
-            return Response({"error": str(exc)}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)
-        return Response(SectionSerializer(sections, many=True).data)
-
-    @action(detail=True, methods=["post"], url_path="adjust-sections")
-    def adjust_sections(self, request: Request, group_pk: int | None = None, pk: int | None = None) -> Response:
-        group_book = self.get_object()
-        adjust_serializer = SectionAdjustSerializer(data=request.data)
-        adjust_serializer.is_valid(raise_exception=True)
-
-        operation = adjust_serializer.validated_data["operation"]
-        section_ids: list[int] = adjust_serializer.validated_data["section_ids"]
-
-        if operation == "merge":
-            if len(section_ids) < 2:
-                return Response(
-                    {"error": "At least 2 section IDs required for merge."},
-                    status=status.HTTP_400_BAD_REQUEST,
-                )
-            sections = list(
-                Section.objects.filter(id__in=section_ids, group_book=group_book).order_by("order")
-            )
-            if len(sections) < 2:
-                return Response(
-                    {"error": "Not enough valid sections found."},
-                    status=status.HTTP_400_BAD_REQUEST,
-                )
-            merged_title = " — ".join(s.title for s in sections)
-            merged_minutes = sum(s.estimated_reading_minutes for s in sections)
-            merged_start = sections[0].start_chapter_index
-            merged_end = sections[-1].end_chapter_index
-            merged_order = sections[0].order
-
-            # Delete old sections
-            Section.objects.filter(id__in=section_ids, group_book=group_book).delete()
-
-            # Create merged section
-            merged = Section.objects.create(
-                group_book=group_book,
-                title=merged_title,
-                order=merged_order,
-                start_chapter_index=merged_start,
-                end_chapter_index=merged_end,
-                estimated_reading_minutes=merged_minutes,
-            )
-            # Reorder remaining sections
-            _renumber_sections(group_book)
-            return Response(SectionSerializer(merged).data)
-
-        if operation == "split":
-            if len(section_ids) != 1:
-                return Response(
-                    {"error": "Exactly 1 section ID required for split."},
-                    status=status.HTTP_400_BAD_REQUEST,
-                )
-            split_at = adjust_serializer.validated_data.get("split_at", 2)
-            section = get_object_or_404(Section, id=section_ids[0], group_book=group_book)
-            chapters = section.end_chapter_index - section.start_chapter_index
-            if chapters < split_at:
-                return Response(
-                    {"error": f"Section only has {chapters} chapters, cannot split into {split_at}."},
-                    status=status.HTTP_400_BAD_REQUEST,
-                )
-
-            # Delete original
-            orig_order = section.order
-            orig_title = section.title
-            section.delete()
-
-            # Create split sections
-            chunk_size = max(1, chapters // split_at)
-            new_sections: list[Section] = []
-            for i in range(split_at):
-                start_idx = section.start_chapter_index + i * chunk_size
-                end_idx = start_idx + chunk_size if i < split_at - 1 else section.end_chapter_index
-                minutes_each = max(1, section.estimated_reading_minutes // split_at)
-                new_sec = Section.objects.create(
-                    group_book=group_book,
-                    title=f"{orig_title} (Part {i + 1})",
-                    order=orig_order + i,
-                    start_chapter_index=start_idx,
-                    end_chapter_index=end_idx,
-                    estimated_reading_minutes=minutes_each,
-                )
-                new_sections.append(new_sec)
-
-            _renumber_sections(group_book)
-            return Response(SectionSerializer(new_sections, many=True).data)
-
-        return Response({"error": "Invalid operation."}, status=status.HTTP_400_BAD_REQUEST)
-
-    @action(detail=True, methods=["get", "post", "delete"], url_path="schedule")
-    def schedule(self, request: Request, group_pk: int | None = None, pk: int | None = None) -> Response:
-        group_book = self.get_object()
-
-        if request.method == "GET":
-            schedules = ReadingSchedule.objects.filter(group_book=group_book).order_by("meeting_number")
-            return Response(ReadingScheduleSerializer(schedules, many=True).data)
-
-        if request.method == "POST":
-            ReadingSchedule.objects.filter(group_book=group_book).delete()
-            num_meetings = int(request.data.get("num_meetings", 4))
-            try:
-                schedules = apply_schedule(group_book, num_meetings=num_meetings)
-            except Exception as exc:
-                logger.exception("Schedule generation failed for group_book %s", group_book.id)
-                return Response({"error": str(exc)}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)
-            return Response(
-                ReadingScheduleSerializer(schedules, many=True).data,
-                status=status.HTTP_201_CREATED,
-            )
-
-        if request.method == "DELETE":
-            ReadingSchedule.objects.filter(group_book=group_book).delete()
-            return Response(status=status.HTTP_204_NO_CONTENT)
-
-    @action(detail=True, methods=["get", "patch"], url_path="progress")
-    def progress(self, request: Request, group_pk: int | None = None, pk: int | None = None) -> Response:
-        group_book = self.get_object()
-
-        if request.method == "GET":
-            progress_records = MemberProgress.objects.filter(
-                group_book=group_book
-            ).select_related("user", "current_section")
-            return Response(MemberProgressSerializer(progress_records, many=True).data)
-
-        # PATCH: update own progress
-        progress_obj, _created = MemberProgress.objects.get_or_create(
-            user=request.user, group_book=group_book,
-        )
-        serializer = MemberProgressSerializer(progress_obj, data=request.data, partial=True)
+    @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)
-        serializer.save()
+
+        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)
+
+        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(
+            GroupInviteSerializer(invite, context={"request": request}).data,
+            status=status.HTTP_201_CREATED,
+        )
+
+    @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)
+
+        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)
 
-def _renumber_sections(group_book: GroupBook) -> None:
-    """Re-number sections sequentially by their current order."""
-    sections = list(Section.objects.filter(group_book=group_book).order_by("order"))
-    for idx, section in enumerate(sections):
-        if section.order != idx + 1:
-            section.order = idx + 1
-            section.save(update_fields=["order"])
+        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)
+
+
+class JoinGroupViewSet(viewsets.GenericViewSet):
+    """Public(ish) endpoint for joining a group via an invite code."""
+
+    permission_classes = [IsAuthenticated]
+
+    @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 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)
+
+        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,
+            },
+        })
+
+    @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/django.py

@@ -39,9 +39,9 @@ INSTALLED_APPS = [
     # Local apps
     "apps.users",
     "apps.books",
-    "apps.groups",
     "apps.annotations",
     "apps.reader",
+    "apps.groups",
 ]
 
 MIDDLEWARE = [

backend/config/urls.py

@@ -6,9 +6,9 @@ urlpatterns = [
     path("admin/", admin.site.urls),
     path("api/auth/", include("apps.users.urls")),
     path("api/books/", include("apps.books.urls")),
-    path("api/groups/", include("apps.groups.urls")),
     path("api/annotations/", include("apps.annotations.urls")),
     path("api/reader/", include("apps.reader.urls")),
+    path("api/", include("apps.groups.urls")),
 ]
 
 if settings.DEBUG:

frontend/src/App.tsx

@@ -12,9 +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 GroupsPage = lazy(() => import("./pages/GroupsPage").then((m) => ({ default: m.GroupsPage })));
+const GroupsListPage = lazy(() => import("./pages/GroupsListPage").then((m) => ({ default: m.GroupsListPage })));
 const GroupDetailPage = lazy(() => import("./pages/GroupDetailPage").then((m) => ({ default: m.GroupDetailPage })));
-const GroupBookPage = lazy(() => import("./pages/GroupBookPage").then((m) => ({ default: m.GroupBookPage })));
+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"));
 
@@ -47,10 +48,11 @@ function AppRoutes() {
         <Route path="/reader/:id" element={<ProtectedRoute><ReaderRedirect /></ProtectedRoute>} />
         <Route path="/add" element={<ProtectedRoute><AddBookPage /></ProtectedRoute>} />
         <Route path="/settings" element={<ProtectedRoute><SettingsPage /></ProtectedRoute>} />
-        <Route path="/groups" element={<ProtectedRoute><GroupsPage /></ProtectedRoute>} />
-        <Route path="/groups/:groupId" element={<ProtectedRoute><GroupDetailPage /></ProtectedRoute>} />
-        <Route path="/groups/:groupId/books/:bookId" element={<ProtectedRoute><GroupBookPage /></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

@@ -1,36 +1,36 @@
 import api from "./client";
 import type {
-  AddMemberPayload,
-  AdjustSectionsPayload,
-  CreateGroupBookPayload,
   CreateGroupPayload,
-  GroupBook,
-  GroupBookDetail,
-  MemberProgress,
-  ReadingGroup,
-  ReadingGroupDetail,
-  ReadingSchedule,
-  Section,
-} from "../types/group";
+  CreateInvitePayload,
+  GroupDetail,
+  GroupInvite,
+  GroupListItem,
+  InviteValidation,
+  JoinRequest,
+  UpdateGroupPayload,
+} from "../../packages/shared/src/types";
 
 export const groupsApi = {
-  // ---- Reading Groups ----
+  // ---- Group CRUD ----
 
-  async listGroups(): Promise<ReadingGroup[]> {
-    const { data } = await api.get<{ count: number; results: ReadingGroup[] } | ReadingGroup[]>(
-      "/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 getGroup(id: number): Promise<ReadingGroupDetail> {
-    const { data } = await api.get<ReadingGroupDetail>(`/groups/${id}/`);
+  async getGroup(id: number): Promise<GroupDetail> {
+    const { data } = await api.get<GroupDetail>(`/groups/${id}/`);
     return data;
   },
 
-  async createGroup(payload: CreateGroupPayload): Promise<ReadingGroup> {
-    const { data } = await api.post<ReadingGroup>("/groups/", payload);
+  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;
   },
 
@@ -38,114 +38,63 @@ export const groupsApi = {
     await api.delete(`/groups/${id}/`);
   },
 
-  async addMember(groupId: number, payload: AddMemberPayload): Promise<void> {
-    await api.post(`/groups/${groupId}/add_member/`, payload);
+  // ---- Members ----
+
+  async removeMember(groupId: number, userId: number): Promise<void> {
+    await api.delete(`/groups/${groupId}/members/${userId}/`);
   },
 
-  async removeMember(groupId: number, payload: AddMemberPayload): Promise<void> {
-    await api.post(`/groups/${groupId}/remove_member/`, payload);
+  async updateMemberRole(groupId: number, userId: number, role: "admin" | "member"): Promise<void> {
+    await api.patch(`/groups/${groupId}/members/${userId}/role/`, { role });
   },
 
-  // ---- Group Books ----
-
-  async listGroupBooks(groupId: number): Promise<GroupBook[]> {
-    const { data } = await api.get<GroupBook[]>(`/groups/${groupId}/books/`);
-    return Array.isArray(data) ? data : (data as { results: GroupBook[] }).results ?? [];
-  },
-
-  async getGroupBook(groupId: number, bookId: number): Promise<GroupBookDetail> {
-    const { data } = await api.get<GroupBookDetail>(`/groups/${groupId}/books/${bookId}/`);
+  async leaveGroup(groupId: number): Promise<{ detail: string }> {
+    const { data } = await api.post<{ detail: string }>(`/groups/${groupId}/leave/`);
     return data;
   },
 
-  async createGroupBook(
-    groupId: number,
-    payload: CreateGroupBookPayload
-  ): Promise<GroupBookDetail> {
-    const { data } = await api.post<GroupBookDetail>(
-      `/groups/${groupId}/books/`,
-      payload
-    );
+  // ---- Invites ----
+
+  async listInvites(groupId: number): Promise<GroupInvite[]> {
+    const { data } = await api.get<GroupInvite[]>(`/groups/${groupId}/invites/`);
     return data;
   },
 
-  async deleteGroupBook(groupId: number, bookId: number): Promise<void> {
-    await api.delete(`/groups/${groupId}/books/${bookId}/`);
-  },
-
-  // ---- Sections ----
-
-  async detectSections(
-    groupId: number,
-    bookId: number
-  ): Promise<Section[]> {
-    const { data } = await api.post<Section[]>(
-      `/groups/${groupId}/books/${bookId}/detect-sections/`
-    );
+  async createInvite(groupId: number, payload: CreateInvitePayload = {}): Promise<GroupInvite> {
+    const { data } = await api.post<GroupInvite>(`/groups/${groupId}/invites/`, payload);
     return data;
   },
 
-  async adjustSections(
-    groupId: number,
-    bookId: number,
-    payload: AdjustSectionsPayload
-  ): Promise<Section | Section[]> {
-    const { data } = await api.post<Section | Section[]>(
-      `/groups/${groupId}/books/${bookId}/adjust-sections/`,
-      payload
-    );
+  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;
   },
 
-  // ---- Schedule ----
-
-  async getSchedule(
-    groupId: number,
-    bookId: number
-  ): Promise<ReadingSchedule[]> {
-    const { data } = await api.get<ReadingSchedule[]>(
-      `/groups/${groupId}/books/${bookId}/schedule/`
-    );
+  async approveRequest(groupId: number, requestId: number): Promise<JoinRequest> {
+    const { data } = await api.post<JoinRequest>(`/groups/${groupId}/requests/${requestId}/approve/`);
     return data;
   },
 
-  async generateSchedule(
-    groupId: number,
-    bookId: number,
-    numMeetings: number = 4
-  ): Promise<ReadingSchedule[]> {
-    const { data } = await api.post<ReadingSchedule[]>(
-      `/groups/${groupId}/books/${bookId}/schedule/`,
-      { num_meetings: numMeetings }
-    );
+  async rejectRequest(groupId: number, requestId: number): Promise<JoinRequest> {
+    const { data } = await api.post<JoinRequest>(`/groups/${groupId}/requests/${requestId}/reject/`);
     return data;
   },
 
-  async deleteSchedule(groupId: number, bookId: number): Promise<void> {
-    await api.delete(`/groups/${groupId}/books/${bookId}/schedule/`);
-  },
+  // ---- Join via Invite ----
 
-  // ---- Progress ----
-
-  async getProgress(
-    groupId: number,
-    bookId: number
-  ): Promise<MemberProgress[]> {
-    const { data } = await api.get<MemberProgress[]>(
-      `/groups/${groupId}/books/${bookId}/progress/`
-    );
+  async validateInvite(code: string): Promise<InviteValidation> {
+    const { data } = await api.get<InviteValidation>(`/join/${code}/`);
     return data;
   },
 
-  async updateProgress(
-    groupId: number,
-    bookId: number,
-    payload: { current_section?: number; completed_sections?: number[] }
-  ): Promise<MemberProgress> {
-    const { data } = await api.patch<MemberProgress>(
-      `/groups/${groupId}/books/${bookId}/progress/`,
-      payload
-    );
+  async joinViaInvite(code: string): Promise<GroupDetail> {
+    const { data } = await api.post<GroupDetail>(`/join/${code}/`);
     return data;
   },
 };

frontend/src/locales/en-US.ts

@@ -245,54 +245,6 @@ const enUS = {
     home: "Home",
     bookmarksNotes: "Bookmarks & Notes",
   },
-  groups: {
-    title: "Reading Groups",
-    createGroup: "Create Group",
-    create: "Create",
-    cancel: "Cancel",
-    groupName: "Group Name",
-    groupNamePlaceholder: "Enter group name",
-    description: "Description",
-    descriptionPlaceholder: "What is this group about?",
-    optional: "Optional",
-    noGroups: "No groups yet",
-    noGroupsHint: "Create a reading group to start reading together!",
-    members: "Members",
-    admin: "Admin",
-    addMember: "Add Member",
-    memberIdPlaceholder: "Enter user ID",
-    add: "Add",
-    remove: "Remove",
-    books: "Group Books",
-    uploadEpub: "Upload EPUB",
-    selectEbook: "Select an EPUB to share with the group",
-    noEpubBooks: "No EPUB files uploaded yet",
-    uploadFirst: "Upload an EPUB first",
-    confirmUpload: "Confirm Upload",
-    noBooks: "No books in this group yet",
-    sections: "Sections",
-    schedule: "Schedule",
-    progress: "Progress",
-    detectSections: "Auto-Detect Sections",
-    mergeSections: "Merge Sections",
-    selectSectionsHint: "Click sections to select for merging",
-    merge: "Merge",
-    clear: "Clear",
-    split: "Split",
-    splitInto: "Split into",
-    parts: "parts",
-    splitBtn: "Split",
-    noSections: "No sections detected yet",
-    noSectionsHint: 'Click "Auto-Detect Sections" to parse the EPUB chapters into reading sections.',
-    readingSchedule: "Reading Schedule",
-    generateSchedule: "Generate Schedule",
-    noSchedule: "No schedule generated yet",
-    noScheduleHint: "Detect sections first, then generate a reading schedule for your group.",
-    meeting: "Meeting",
-    memberProgress: "Member Progress",
-    noProgress: "No progress data yet",
-    noProgressHint: "Members will show progress once they start reading.",
-  },
 } as const;
 
 export default enUS;

frontend/src/locales/es-ES.ts

@@ -247,54 +247,6 @@ const esES: Locale = {
     home: "Inicio",
     bookmarksNotes: "Marcadores y notas",
   },
-  groups: {
-    title: "Grupos de Lectura",
-    createGroup: "Crear Grupo",
-    create: "Crear",
-    cancel: "Cancelar",
-    groupName: "Nombre del Grupo",
-    groupNamePlaceholder: "Ingresa el nombre del grupo",
-    description: "Descripción",
-    descriptionPlaceholder: "¿De qué trata este grupo?",
-    optional: "Opcional",
-    noGroups: "Aún no hay grupos",
-    noGroupsHint: "¡Crea un grupo de lectura para leer juntos!",
-    members: "Miembros",
-    admin: "Admin",
-    addMember: "Agregar Miembro",
-    memberIdPlaceholder: "Ingresa ID de usuario",
-    add: "Agregar",
-    remove: "Eliminar",
-    books: "Libros del Grupo",
-    uploadEpub: "Subir EPUB",
-    selectEbook: "Selecciona un EPUB para compartir con el grupo",
-    noEpubBooks: "No hay archivos EPUB subidos aún",
-    uploadFirst: "Sube un EPUB primero",
-    confirmUpload: "Confirmar Subida",
-    noBooks: "No hay libros en este grupo aún",
-    sections: "Secciones",
-    schedule: "Calendario",
-    progress: "Progreso",
-    detectSections: "Auto-Detectar Secciones",
-    mergeSections: "Fusionar Secciones",
-    selectSectionsHint: "Haz clic en las secciones para seleccionar y fusionar",
-    merge: "Fusionar",
-    clear: "Limpiar",
-    split: "Dividir",
-    splitInto: "Dividir en",
-    parts: "partes",
-    splitBtn: "Dividir",
-    noSections: "No se detectaron secciones",
-    noSectionsHint: 'Haz clic en "Auto-Detectar Secciones" para analizar los capítulos del EPUB.',
-    readingSchedule: "Calendario de Lectura",
-    generateSchedule: "Generar Calendario",
-    noSchedule: "No hay calendario generado",
-    noScheduleHint: "Detecta secciones primero, luego genera un calendario de lectura para tu grupo.",
-    meeting: "Reunión",
-    memberProgress: "Progreso de Miembros",
-    noProgress: "Sin datos de progreso",
-    noProgressHint: "Los miembros mostrarán progreso cuando comiencen a leer.",
-  },
 };
 
 export default esES;

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/GroupBookPage.tsx

@@ -1,426 +0,0 @@
-import React, { useCallback, useEffect, useState } from "react";
-import { useNavigate, useParams } from "react-router-dom";
-import { useTranslation } from "react-i18n-lite";
-import { groupsApi } from "../api/groups";
-import { getApiErrorMessage } from "../api/errors";
-import type {
-  GroupBookDetail,
-  ReadingSchedule,
-  Section,
-  MemberProgress,
-} from "../types/group";
-
-export function GroupBookPage() {
-  const { t } = useTranslation();
-  const navigate = useNavigate();
-  const { groupId, bookId } = useParams<{ groupId: string; bookId: string }>();
-
-  const [book, setBook] = useState<GroupBookDetail | null>(null);
-  const [sections, setSections] = useState<Section[]>([]);
-  const [schedules, setSchedules] = useState<ReadingSchedule[]>([]);
-  const [progress, setProgress] = useState<MemberProgress[]>([]);
-  const [loading, setLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
-  const [tab, setTab] = useState<"sections" | "schedule" | "progress">("sections");
-
-  // Merge state
-  const [selectedForMerge, setSelectedForMerge] = useState<number[]>([]);
-  const [splitSectionId, setSplitSectionId] = useState<number | null>(null);
-  const [splitAt, setSplitAt] = useState(2);
-
-  const gId = Number(groupId);
-  const bId = Number(bookId);
-
-  const loadData = useCallback(async () => {
-    if (!gId || !bId) return;
-    setLoading(true);
-    try {
-      const [bookData, schedData, progData] = await Promise.all([
-        groupsApi.getGroupBook(gId, bId),
-        groupsApi.getSchedule(gId, bId).catch(() => [] as ReadingSchedule[]),
-        groupsApi.getProgress(gId, bId).catch(() => [] as MemberProgress[]),
-      ]);
-      setBook(bookData);
-      setSections(bookData.sections ?? []);
-      setSchedules(schedData);
-      setProgress(progData);
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to load book"));
-    } finally {
-      setLoading(false);
-    }
-  }, [gId, bId]);
-
-  useEffect(() => {
-    loadData();
-  }, [loadData]);
-
-  const handleDetectSections = async () => {
-    if (!gId || !bId) return;
-    try {
-      const newSections = await groupsApi.detectSections(gId, bId);
-      setSections(newSections);
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to detect sections"));
-    }
-  };
-
-  const handleMerge = async () => {
-    if (selectedForMerge.length < 2 || !gId || !bId) return;
-    try {
-      await groupsApi.adjustSections(gId, bId, {
-        operation: "merge",
-        section_ids: selectedForMerge,
-      });
-      setSelectedForMerge([]);
-      await loadData();
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to merge sections"));
-    }
-  };
-
-  const handleSplit = async () => {
-    if (!splitSectionId || !gId || !bId) return;
-    try {
-      await groupsApi.adjustSections(gId, bId, {
-        operation: "split",
-        section_ids: [splitSectionId],
-        split_at: splitAt,
-      });
-      setSplitSectionId(null);
-      await loadData();
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to split section"));
-    }
-  };
-
-  const handleGenerateSchedule = async () => {
-    if (!gId || !bId) return;
-    try {
-      const newSched = await groupsApi.generateSchedule(gId, bId, 4);
-      setSchedules(newSched);
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to generate schedule"));
-    }
-  };
-
-  const toggleMergeSelect = (id: number) => {
-    setSelectedForMerge((prev) =>
-      prev.includes(id) ? prev.filter((s) => s !== id) : [...prev, id]
-    );
-  };
-
-  const formatMinutes = (mins: number): string => {
-    if (mins < 60) return `${mins}m`;
-    const h = Math.floor(mins / 60);
-    const m = mins % 60;
-    return m > 0 ? `${h}h ${m}m` : `${h}h`;
-  };
-
-  if (loading) {
-    return (
-      <div style={{ maxWidth: 800, margin: "0 auto", padding: 16, minHeight: "100vh", background: "#f8f9fa" }}>
-        <p style={{ textAlign: "center", color: "#888", padding: 40 }}>{t("common.loading")}</p>
-      </div>
-    );
-  }
-
-  if (!book) {
-    return (
-      <div style={{ maxWidth: 800, margin: "0 auto", padding: 16, minHeight: "100vh", background: "#f8f9fa" }}>
-        <p style={{ textAlign: "center", color: "#e74c3c", padding: 40 }}>Book not found</p>
-        <button onClick={() => navigate(`/groups/${groupId}`)} style={{ display: "block", margin: "0 auto" }}>← Back</button>
-      </div>
-    );
-  }
-
-  return (
-    <div style={{ maxWidth: 800, margin: "0 auto", padding: 16, minHeight: "100vh", background: "#f8f9fa" }}>
-      {/* Header */}
-      <header style={{ display: "flex", justifyContent: "space-between", alignItems: "center", padding: "16px 0", borderBottom: "1px solid #eee", marginBottom: 20 }}>
-        <div>
-          <h1 style={{ fontSize: 24, fontWeight: 700, color: "#1a1a2e", margin: 0 }}>{book.title}</h1>
-          <p style={{ margin: 4, fontSize: 13, color: "#888" }}>
-            {book.ebook.author && `by ${book.ebook.author} · `}
-            {book.ebook.page_count} chapters · {book.ebook.format.toUpperCase()}
-          </p>
-        </div>
-        <button onClick={() => navigate(`/groups/${groupId}`)} style={{ padding: "8px 16px", borderRadius: 6, border: "1px solid #ddd", background: "#fff", cursor: "pointer", fontSize: 14 }}>
-          ← {t("common.back")}
-        </button>
-      </header>
-
-      {error && (
-        <div style={{ background: "#fde8e8", padding: 12, borderRadius: 6, color: "#e74c3c", fontSize: 14, marginBottom: 16 }}>
-          {error}
-          <button onClick={() => setError(null)} style={{ marginLeft: 12, background: "none", border: "none", cursor: "pointer", fontWeight: 600 }}>✕</button>
-        </div>
-      )}
-
-      {/* Tabs */}
-      <div style={{ display: "flex", gap: 4, marginBottom: 20, background: "#eee", borderRadius: 8, padding: 4 }}>
-        {(["sections", "schedule", "progress"] as const).map((t) => (
-          <button
-            key={t}
-            onClick={() => setTab(t)}
-            style={{
-              flex: 1, padding: "10px 16px", borderRadius: 6, border: "none",
-              fontSize: 14, fontWeight: 600, cursor: "pointer",
-              background: tab === t ? "#fff" : "transparent",
-              color: tab === t ? "#1a1a2e" : "#888",
-              boxShadow: tab === t ? "0 1px 4px rgba(0,0,0,0.1)" : "none",
-            }}
-          >
-            {t === "sections" ? t("groups.sections") : t === "schedule" ? t("groups.schedule") : t("groups.progress")}
-          </button>
-        ))}
-      </div>
-
-      {/* Sections Tab */}
-      {tab === "sections" && (
-        <section>
-          <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center", marginBottom: 16 }}>
-            <h2 style={{ fontSize: 18, fontWeight: 600, color: "#1a1a2e", margin: 0 }}>
-              {sections.length} {t("groups.sections")}
-            </h2>
-            <div style={{ display: "flex", gap: 8 }}>
-              <button
-                onClick={handleDetectSections}
-                style={{ padding: "8px 16px", borderRadius: 6, border: "none", background: "#1a1a2e", color: "#fff", fontSize: 13, fontWeight: 600, cursor: "pointer" }}
-              >
-                {t("groups.detectSections")}
-              </button>
-            </div>
-          </div>
-
-          {/* Merge controls */}
-          <div style={{ background: "#fff", padding: 16, borderRadius: 10, marginBottom: 12, boxShadow: "0 1px 4px rgba(0,0,0,0.06)" }}>
-            <div style={{ display: "flex", alignItems: "center", gap: 10, flexWrap: "wrap" }}>
-              <span style={{ fontSize: 14, fontWeight: 600, color: "#555" }}>{t("groups.mergeSections")}:</span>
-              <span style={{ fontSize: 13, color: "#888" }}>
-                {selectedForMerge.length === 0
-                  ? t("groups.selectSectionsHint")
-                  : `${selectedForMerge.length} selected`}
-              </span>
-              {selectedForMerge.length >= 2 && (
-                <button
-                  onClick={handleMerge}
-                  style={{ padding: "6px 14px", borderRadius: 6, border: "none", background: "#27ae60", color: "#fff", fontSize: 13, fontWeight: 600, cursor: "pointer" }}
-                >
-                  {t("groups.merge")}
-                </button>
-              )}
-              {selectedForMerge.length > 0 && (
-                <button
-                  onClick={() => setSelectedForMerge([])}
-                  style={{ padding: "6px 12px", borderRadius: 6, border: "1px solid #ddd", background: "#fff", fontSize: 13, cursor: "pointer" }}
-                >
-                  {t("groups.clear")}
-                </button>
-              )}
-            </div>
-          </div>
-
-          {sections.length === 0 ? (
-            <div style={{ textAlign: "center", padding: 40, color: "#888" }}>
-              <p style={{ fontSize: 16 }}>{t("groups.noSections")}</p>
-              <p style={{ fontSize: 14 }}>{t("groups.noSectionsHint")}</p>
-            </div>
-          ) : (
-            <div style={{ display: "flex", flexDirection: "column", gap: 10 }}>
-              {sections.map((section) => (
-                <div
-                  key={section.id}
-                  style={{
-                    background: selectedForMerge.includes(section.id) ? "#e8f0fe" : "#fff",
-                    border: selectedForMerge.includes(section.id) ? "2px solid #1a1a2e" : "1px solid #eee",
-                    padding: 16, borderRadius: 10, cursor: "pointer",
-                    boxShadow: "0 1px 4px rgba(0,0,0,0.06)",
-                    transition: "all 0.15s",
-                  }}
-                  onClick={() => toggleMergeSelect(section.id)}
-                >
-                  <div style={{ display: "flex", justifyContent: "space-between", alignItems: "flex-start" }}>
-                    <div style={{ flex: 1 }}>
-                      <div style={{ display: "flex", alignItems: "center", gap: 8 }}>
-                        <span style={{
-                          background: "#1a1a2e", color: "#fff", borderRadius: 20,
-                          width: 26, height: 26, display: "flex", alignItems: "center", justifyContent: "center",
-                          fontSize: 13, fontWeight: 700, flexShrink: 0,
-                        }}>
-                          {section.order}
-                        </span>
-                        <h3 style={{ margin: 0, fontSize: 15, fontWeight: 600, color: "#1a1a2e" }}>{section.title}</h3>
-                      </div>
-                      <p style={{ margin: "6px 0 0 34px", fontSize: 13, color: "#888" }}>
-                        Ch. {section.start_chapter_index}–{section.end_chapter_index - 1} · ~{formatMinutes(section.estimated_reading_minutes)} reading time
-                      </p>
-                    </div>
-                    <button
-                      onClick={(e) => {
-                        e.stopPropagation();
-                        setSplitSectionId(splitSectionId === section.id ? null : section.id);
-                      }}
-                      style={{
-                        padding: "4px 10px", borderRadius: 4, border: "1px solid #ddd",
-                        background: splitSectionId === section.id ? "#1a1a2e" : "#fff",
-                        color: splitSectionId === section.id ? "#fff" : "#666",
-                        fontSize: 12, cursor: "pointer", flexShrink: 0,
-                      }}
-                    >
-                      {t("groups.split")}
-                    </button>
-                  </div>
-                  {splitSectionId === section.id && (
-                    <div
-                      style={{ marginTop: 10, padding: 10, background: "#f8f9fa", borderRadius: 6, display: "flex", alignItems: "center", gap: 8 }}
-                      onClick={(e) => e.stopPropagation()}
-                    >
-                      <span style={{ fontSize: 13 }}>{t("groups.splitInto")}</span>
-                      <input
-                        type="number"
-                        value={splitAt}
-                        min={2}
-                        max={10}
-                        onChange={(e) => setSplitAt(Number(e.target.value))}
-                        style={{ width: 50, padding: "4px 8px", borderRadius: 4, border: "1px solid #ddd", fontSize: 13, textAlign: "center" }}
-                      />
-                      <span style={{ fontSize: 13 }}>{t("groups.parts")}</span>
-                      <button
-                        onClick={handleSplit}
-                        style={{ padding: "4px 12px", borderRadius: 4, border: "none", background: "#1a1a2e", color: "#fff", fontSize: 12, cursor: "pointer" }}
-                      >
-                        {t("groups.splitBtn")}
-                      </button>
-                    </div>
-                  )}
-                </div>
-              ))}
-            </div>
-          )}
-        </section>
-      )}
-
-      {/* Schedule Tab */}
-      {tab === "schedule" && (
-        <section>
-          <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center", marginBottom: 16 }}>
-            <h2 style={{ fontSize: 18, fontWeight: 600, color: "#1a1a2e", margin: 0 }}>
-              {t("groups.readingSchedule")}
-            </h2>
-            <button
-              onClick={handleGenerateSchedule}
-              style={{ padding: "8px 16px", borderRadius: 6, border: "none", background: "#1a1a2e", color: "#fff", fontSize: 13, fontWeight: 600, cursor: "pointer" }}
-            >
-              {t("groups.generateSchedule")}
-            </button>
-          </div>
-
-          {schedules.length === 0 ? (
-            <div style={{ textAlign: "center", padding: 40, color: "#888" }}>
-              <p style={{ fontSize: 16 }}>{t("groups.noSchedule")}</p>
-              <p style={{ fontSize: 14 }}>{t("groups.noScheduleHint")}</p>
-            </div>
-          ) : (
-            <div style={{ display: "flex", flexDirection: "column", gap: 16 }}>
-              {schedules.map((s) => (
-                <div
-                  key={s.id}
-                  style={{ background: "#fff", padding: 20, borderRadius: 12, boxShadow: "0 2px 8px rgba(0,0,0,0.06)" }}
-                >
-                  <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center", marginBottom: 12 }}>
-                    <div>
-                      <h3 style={{ margin: 0, fontSize: 17, fontWeight: 700, color: "#1a1a2e" }}>
-                        {t("groups.meeting")} {s.meeting_number}
-                      </h3>
-                      <p style={{ margin: "4px 0 0", fontSize: 13, color: "#888" }}>
-                        Week of {new Date(s.week_date).toLocaleDateString("en-US", { month: "long", day: "numeric", year: "numeric" })}
-                      </p>
-                    </div>
-                    <span style={{
-                      background: "#f0f0f0", padding: "6px 12px", borderRadius: 20,
-                      fontSize: 13, fontWeight: 600, color: "#555",
-                    }}>
-                      {s.section_details.reduce((sum, sec) => sum + sec.estimated_reading_minutes, 0) > 0
-                        ? `~${formatMinutes(s.section_details.reduce((sum, sec) => sum + sec.estimated_reading_minutes, 0))}`
-                        : ""}
-                    </span>
-                  </div>
-                  <div style={{ display: "flex", flexDirection: "column", gap: 6 }}>
-                    {s.section_details.map((sec) => (
-                      <div
-                        key={sec.id}
-                        style={{
-                          display: "flex", alignItems: "center", gap: 10, padding: "8px 12px",
-                          background: "#f8f9fa", borderRadius: 6, fontSize: 14,
-                        }}
-                      >
-                        <span style={{
-                          background: "#1a1a2e", color: "#fff", borderRadius: 12,
-                          width: 22, height: 22, display: "flex", alignItems: "center", justifyContent: "center",
-                          fontSize: 11, fontWeight: 700, flexShrink: 0,
-                        }}>
-                          {sec.order}
-                        </span>
-                        <span style={{ flex: 1 }}>{sec.title}</span>
-                        <span style={{ fontSize: 12, color: "#999" }}>{formatMinutes(sec.estimated_reading_minutes)}</span>
-                      </div>
-                    ))}
-                  </div>
-                </div>
-              ))}
-            </div>
-          )}
-        </section>
-      )}
-
-      {/* Progress Tab */}
-      {tab === "progress" && (
-        <section>
-          <h2 style={{ fontSize: 18, fontWeight: 600, color: "#1a1a2e", margin: "0 0 16px" }}>
-            {t("groups.memberProgress")}
-          </h2>
-          {progress.length === 0 ? (
-            <div style={{ textAlign: "center", padding: 40, color: "#888" }}>
-              <p style={{ fontSize: 16 }}>{t("groups.noProgress")}</p>
-              <p style={{ fontSize: 14 }}>{t("groups.noProgressHint")}</p>
-            </div>
-          ) : (
-            <div style={{ display: "flex", flexDirection: "column", gap: 10 }}>
-              {progress.map((p) => {
-                const totalSections = sections.length;
-                const completed = p.completed_sections.length;
-                const pct = totalSections > 0 ? Math.round((completed / totalSections) * 100) : 0;
-                return (
-                  <div
-                    key={p.id}
-                    style={{ background: "#fff", padding: 16, borderRadius: 10, boxShadow: "0 1px 4px rgba(0,0,0,0.06)" }}
-                  >
-                    <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center", marginBottom: 8 }}>
-                      <span style={{ fontSize: 15, fontWeight: 600 }}>{p.user_email}</span>
-                      <span style={{ fontSize: 13, color: "#888" }}>{completed}/{totalSections} · {pct}%</span>
-                    </div>
-                    <div style={{ height: 6, background: "#eee", borderRadius: 3, overflow: "hidden" }}>
-                      <div
-                        style={{
-                          height: "100%", borderRadius: 3,
-                          background: "linear-gradient(90deg, #27ae60, #2ecc71)",
-                          width: `${pct}%`, transition: "width 0.3s",
-                        }}
-                      />
-                    </div>
-                    {p.current_section_title && (
-                      <p style={{ margin: "8px 0 0", fontSize: 13, color: "#888" }}>
-                        Currently: {p.current_section_title}
-                      </p>
-                    )}
-                  </div>
-                );
-              })}
-            </div>
-          )}
-        </section>
-      )}
-    </div>
-  );
-}

frontend/src/pages/GroupDetailPage.tsx

@@ -1,300 +1,334 @@
 import React, { useCallback, useEffect, useState } from "react";
 import { useNavigate, useParams } from "react-router-dom";
-import { useTranslation } from "react-i18n-lite";
 import { groupsApi } from "../api/groups";
-import { booksApi } from "../api/books";
-import { getApiErrorMessage } from "../api/errors";
-import type { ReadingGroupDetail, GroupBook, GroupBookDetail } from "../types/group";
-import type { EBookListItem } from "../types/book";
+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 { t } = useTranslation();
+  const { id } = useParams<{ id: string }>();
   const navigate = useNavigate();
-  const { groupId } = useParams<{ groupId: string }>();
-  const [group, setGroup] = useState<ReadingGroupDetail | null>(null);
-  const [books, setBooks] = useState<GroupBook[]>([]);
+  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);
 
-  // Upload state
-  const [showUpload, setShowUpload] = useState(false);
-  const [ebooks, setEbooks] = useState<EBookListItem[]>([]);
-  const [selectedEbookId, setSelectedEbookId] = useState<number | null>(null);
-  const [uploading, setUploading] = useState(false);
+  const groupId = Number(id);
+  const isAdmin = group?.user_role === "admin";
 
-  // Add member state
-  const [showAddMember, setShowAddMember] = useState(false);
-  const [memberEmail, setMemberEmail] = useState("");
-  const [adding, setAdding] = useState(false);
-
-  const id = Number(groupId);
-
-  const loadData = useCallback(async () => {
-    if (!id) return;
+  const loadGroup = useCallback(async () => {
+    if (!groupId) return;
     setLoading(true);
+    setError(null);
     try {
-      const [groupData, bookData] = await Promise.all([
-        groupsApi.getGroup(id),
-        groupsApi.listGroupBooks(id),
-      ]);
-      setGroup(groupData);
-      setBooks(bookData);
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to load group"));
+      const data = await groupsApi.getGroup(groupId);
+      setGroup(data);
+    } catch (err: unknown) {
+      setError(err instanceof Error ? err.message : "Failed to load group");
     } finally {
       setLoading(false);
     }
-  }, [id]);
+  }, [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(() => {
-    loadData();
-  }, [loadData]);
+    loadGroup();
+  }, [loadGroup]);
 
-  const handleUploadClick = async () => {
-    setShowUpload(true);
+  useEffect(() => {
+    if (group && isAdmin) loadInvites();
+  }, [group, isAdmin, loadInvites]);
+
+  const handleRemoveMember = async (userId: number, memberEmail: string) => {
+    if (!confirm(`Remove ${memberEmail} from the group?`)) return;
     try {
-      const ebookList = await booksApi.getEBooks();
-      setEbooks(ebookList.filter((e) => e.format === "epub"));
-    } catch {
-      // Ebook list fetch failed silently
+      await groupsApi.removeMember(groupId, userId);
+      showToast({ message: "Member removed", variant: "success" });
+      loadGroup();
+    } catch (err: unknown) {
+      showToast({ message: "Failed to remove member", variant: "error" });
     }
   };
 
-  const handleUpload = async () => {
-    if (!selectedEbookId || !id) return;
-    setUploading(true);
+  const handleTransferAdmin = async (userId: number, memberEmail: string) => {
+    if (!confirm(`Transfer admin role to ${memberEmail}? You will become a regular member.`)) return;
     try {
-      const created = await groupsApi.createGroupBook(id, { ebook_id: selectedEbookId });
-      setShowUpload(false);
-      setSelectedEbookId(null);
-      await loadData();
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to upload book to group"));
-    } finally {
-      setUploading(false);
+      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 handleAddMember = async (e: React.FormEvent) => {
-    e.preventDefault();
-    if (!memberEmail.trim() || !id) return;
-    setAdding(true);
+  const handleLeave = async () => {
+    if (!confirm("Are you sure you want to leave this group?")) return;
     try {
-      // Note: In a real implementation, we'd look up user by email.
-      // For now this requires user_id. Email lookup would be an enhancement.
-      await groupsApi.addMember(id, { user_id: Number(memberEmail) });
-      setShowAddMember(false);
-      setMemberEmail("");
-      await loadData();
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to add member. Please use a valid user ID."));
-    } finally {
-      setAdding(false);
+      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 handleRemoveMember = async (userId: number) => {
-    if (!id) return;
+  const handleCreateInvite = async () => {
     try {
-      await groupsApi.removeMember(id, { user_id: userId });
-      await loadData();
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to remove member"));
+      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" });
     }
   };
 
-  if (loading) {
-    return (
-      <div style={{ maxWidth: 700, margin: "0 auto", padding: 16, minHeight: "100vh", background: "#f8f9fa" }}>
-        <p style={{ textAlign: "center", color: "#888", padding: 40 }}>{t("common.loading")}</p>
-      </div>
+  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 (!group) {
-    return (
-      <div style={{ maxWidth: 700, margin: "0 auto", padding: 16, minHeight: "100vh", background: "#f8f9fa" }}>
-        <p style={{ textAlign: "center", color: "#e74c3c", padding: 40 }}>Group not found</p>
-        <button onClick={() => navigate("/groups")} style={{ display: "block", margin: "0 auto" }}>← Back to Groups</button>
-      </div>
-    );
-  }
+  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={{ maxWidth: 700, margin: "0 auto", padding: 16, minHeight: "100vh", background: "#f8f9fa" }}>
-      <header style={{ display: "flex", justifyContent: "space-between", alignItems: "center", padding: "16px 0", borderBottom: "1px solid #eee", marginBottom: 20 }}>
-        <div>
-          <h1 style={{ fontSize: 24, fontWeight: 700, color: "#1a1a2e", margin: 0 }}>{group.name}</h1>
-          {group.description && <p style={{ margin: "4px 0 0", fontSize: 14, color: "#666" }}>{group.description}</p>}
-        </div>
-        <button onClick={() => navigate("/groups")} style={{ padding: "8px 16px", borderRadius: 6, border: "1px solid #ddd", background: "#fff", cursor: "pointer", fontSize: 14 }}>
-          ← {t("common.back")}
-        </button>
-      </header>
+    <div style={S.container}>
+      <button style={S.backBtn} onClick={() => navigate("/groups")}>
+        ← Back to Groups
+      </button>
 
-      {error && (
-        <div style={{ background: "#fde8e8", padding: 12, borderRadius: 6, color: "#e74c3c", fontSize: 14, marginBottom: 16 }}>
-          {error}
-          <button onClick={() => setError(null)} style={{ marginLeft: 12, background: "none", border: "none", cursor: "pointer", fontWeight: 600 }}>✕</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 */}
-      <section style={{ background: "#fff", padding: 20, borderRadius: 12, marginBottom: 20, boxShadow: "0 2px 8px rgba(0,0,0,0.06)" }}>
-        <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center", marginBottom: 12 }}>
-          <h2 style={{ fontSize: 18, fontWeight: 600, color: "#1a1a2e", margin: 0 }}>{t("groups.members")} ({group.members.length})</h2>
-          <button
-            onClick={() => setShowAddMember(!showAddMember)}
-            style={{ padding: "6px 14px", borderRadius: 6, border: "1px solid #ddd", background: "#fff", cursor: "pointer", fontSize: 13 }}
-          >
-            {showAddMember ? t("groups.cancel") : `+ ${t("groups.addMember")}`}
-          </button>
-        </div>
-        {showAddMember && (
-          <form onSubmit={handleAddMember} style={{ display: "flex", gap: 8, marginBottom: 12 }}>
-            <input
-              type="text"
-              value={memberEmail}
-              onChange={(e) => setMemberEmail(e.target.value)}
-              placeholder={t("groups.memberIdPlaceholder")}
-              style={{ flex: 1, padding: "8px 12px", borderRadius: 6, border: "1px solid #ddd", fontSize: 14, outline: "none" }}
-            />
-            <button
-              type="submit"
-              disabled={adding}
-              style={{ padding: "8px 16px", borderRadius: 6, border: "none", background: "#1a1a2e", color: "#fff", fontSize: 14, cursor: "pointer", opacity: adding ? 0.6 : 1 }}
-            >
-              {t("groups.add")}
-            </button>
-          </form>
-        )}
-        <div style={{ display: "flex", flexDirection: "column", gap: 8 }}>
-          {group.members.map((m) => (
-            <div key={m.id} style={{ display: "flex", justifyContent: "space-between", alignItems: "center", padding: "8px 0", borderBottom: "1px solid #f0f0f0" }}>
-              <div>
-                <span style={{ fontSize: 14, fontWeight: 500 }}>{m.user_email}</span>
-                <span style={{ marginLeft: 8, fontSize: 12, color: m.role === "admin" ? "#e67e22" : "#999", background: m.role === "admin" ? "#fef3e2" : "#f0f0f0", padding: "2px 8px", borderRadius: 4 }}>
-                  {m.role}
-                </span>
-              </div>
-              {m.role !== "admin" && (
-                <button
-                  onClick={() => handleRemoveMember(m.user)}
-                  style={{ background: "none", border: "none", color: "#e74c3c", cursor: "pointer", fontSize: 13 }}
-                >
-                  {t("groups.remove")}
-                </button>
-              )}
+      <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>
-          ))}
-        </div>
-      </section>
-
-      {/* Books Section */}
-      <section style={{ background: "#fff", padding: 20, borderRadius: 12, boxShadow: "0 2px 8px rgba(0,0,0,0.06)" }}>
-        <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center", marginBottom: 12 }}>
-          <h2 style={{ fontSize: 18, fontWeight: 600, color: "#1a1a2e", margin: 0 }}>{t("groups.books")} ({books.length})</h2>
-          <button
-            onClick={handleUploadClick}
-            style={{ padding: "8px 18px", borderRadius: 8, border: "none", background: "#1a1a2e", color: "#fff", fontSize: 14, fontWeight: 600, cursor: "pointer" }}
-          >
-            {t("groups.uploadEpub")}
-          </button>
-        </div>
-
-        {showUpload && (
-          <div style={{ background: "#f8f9fa", padding: 16, borderRadius: 8, marginBottom: 16 }}>
-            <h3 style={{ fontSize: 15, fontWeight: 600, margin: "0 0 12px" }}>{t("groups.selectEbook")}</h3>
-            {ebooks.length === 0 ? (
-              <div style={{ textAlign: "center", padding: 20, color: "#888" }}>
-                <p>{t("groups.noEpubBooks")}</p>
-                <button onClick={() => navigate("/add")} style={{ marginTop: 8, padding: "8px 16px", borderRadius: 6, border: "1px solid #ddd", background: "#fff", cursor: "pointer", fontSize: 13 }}>
-                  {t("groups.uploadFirst")}
+            {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 style={{ display: "flex", flexDirection: "column", gap: 8, marginBottom: 12, maxHeight: 200, overflowY: "auto" }}>
-                  {ebooks.map((eb) => (
-                    <label
-                      key={eb.id}
-                      style={{
-                        display: "flex", alignItems: "center", gap: 10, padding: "10px 12px",
-                        borderRadius: 8, cursor: "pointer", fontSize: 14,
-                        background: selectedEbookId === eb.id ? "#e8f0fe" : "#fff",
-                        border: selectedEbookId === eb.id ? "2px solid #1a1a2e" : "1px solid #eee",
-                      }}
-                    >
-                      <input
-                        type="radio"
-                        name="ebook"
-                        value={eb.id}
-                        checked={selectedEbookId === eb.id}
-                        onChange={() => setSelectedEbookId(eb.id)}
-                        style={{ accentColor: "#1a1a2e" }}
-                      />
-                      <div>
-                        <strong>{eb.title}</strong>
-                        {eb.author && <span style={{ color: "#888", marginLeft: 8 }}>by {eb.author}</span>}
-                        <span style={{ marginLeft: 8, fontSize: 12, color: "#aaa" }}>({eb.filename})</span>
-                      </div>
-                    </label>
-                  ))}
-                </div>
-                <div style={{ display: "flex", gap: 8 }}>
-                  <button
-                    onClick={handleUpload}
-                    disabled={!selectedEbookId || uploading}
-                    style={{ padding: "10px 20px", borderRadius: 8, border: "none", background: "#1a1a2e", color: "#fff", fontSize: 14, fontWeight: 600, cursor: uploading ? "default" : "pointer", opacity: uploading ? 0.6 : 1 }}
-                  >
-                    {uploading ? t("common.loading") : t("groups.confirmUpload")}
-                  </button>
-                  <button
-                    onClick={() => setShowUpload(false)}
-                    style={{ padding: "10px 20px", borderRadius: 8, border: "1px solid #ddd", background: "#fff", cursor: "pointer", fontSize: 14 }}
-                  >
-                    {t("groups.cancel")}
-                  </button>
-                </div>
-              </div>
             )}
           </div>
-        )}
+        ))}
+      </div>
 
-        {books.length === 0 ? (
-          <p style={{ textAlign: "center", color: "#888", padding: 30 }}>{t("groups.noBooks")}</p>
-        ) : (
-          <div style={{ display: "flex", flexDirection: "column", gap: 10 }}>
-            {books.map((book) => (
-              <div
-                key={book.id}
-                onClick={() => navigate(`/groups/${groupId}/books/${book.id}`)}
-                style={{
-                  display: "flex", justifyContent: "space-between", alignItems: "center",
-                  padding: 16, borderRadius: 10, cursor: "pointer", transition: "background 0.2s",
-                  background: book.status === "active" ? "#f0faf0" : "#fafafa",
-                  border: book.status === "active" ? "2px solid #27ae60" : "1px solid #eee",
-                }}
-                onMouseEnter={(e) => (e.currentTarget.style.background = book.status === "active" ? "#e8f5e9" : "#f5f5f5")}
-                onMouseLeave={(e) => (e.currentTarget.style.background = book.status === "active" ? "#f0faf0" : "#fafafa")}
-              >
-                <div>
-                  <h3 style={{ margin: 0, fontSize: 16, fontWeight: 600, color: "#1a1a2e" }}>
-                    {book.title}
-                    {book.status === "active" && (
-                      <span style={{ marginLeft: 8, fontSize: 11, color: "#27ae60", background: "#e8f5e9", padding: "2px 8px", borderRadius: 4 }}>Active</span>
-                    )}
-                  </h3>
-                  <p style={{ margin: "4px 0 0", fontSize: 13, color: "#888" }}>
-                    {book.section_count} sections · {book.ebook.page_count} chapters · uploaded by {book.uploaded_by_email}
-                  </p>
-                </div>
-                <span style={{ fontSize: 20, color: "#ccc" }}>→</span>
-              </div>
-            ))}
-          </div>
-        )}
-      </section>
+      {/* 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/GroupsPage.tsx

@@ -1,162 +0,0 @@
-import React, { useCallback, useEffect, useState } from "react";
-import { useNavigate } from "react-router-dom";
-import { useTranslation } from "react-i18n-lite";
-import { groupsApi } from "../api/groups";
-import { getApiErrorMessage } from "../api/errors";
-import type { ReadingGroup } from "../types/group";
-
-export function GroupsPage() {
-  const { t } = useTranslation();
-  const navigate = useNavigate();
-  const [groups, setGroups] = useState<ReadingGroup[]>([]);
-  const [loading, setLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
-  const [showCreate, setShowCreate] = useState(false);
-  const [newName, setNewName] = useState("");
-  const [newDesc, setNewDesc] = useState("");
-  const [creating, setCreating] = useState(false);
-
-  const loadGroups = useCallback(async () => {
-    setLoading(true);
-    try {
-      const data = await groupsApi.listGroups();
-      setGroups(data);
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to load groups"));
-    } finally {
-      setLoading(false);
-    }
-  }, []);
-
-  useEffect(() => {
-    loadGroups();
-  }, [loadGroups]);
-
-  const handleCreate = async (e: React.FormEvent) => {
-    e.preventDefault();
-    if (!newName.trim()) return;
-    setCreating(true);
-    try {
-      await groupsApi.createGroup({ name: newName.trim(), description: newDesc.trim() });
-      setShowCreate(false);
-      setNewName("");
-      setNewDesc("");
-      await loadGroups();
-    } catch (err) {
-      setError(getApiErrorMessage(err, "Failed to create group"));
-    } finally {
-      setCreating(false);
-    }
-  };
-
-  return (
-    <div style={{ maxWidth: 700, margin: "0 auto", padding: 16, minHeight: "100vh", background: "#f8f9fa" }}>
-      <header style={{ display: "flex", justifyContent: "space-between", alignItems: "center", padding: "16px 0", borderBottom: "1px solid #eee", marginBottom: 20 }}>
-        <h1 style={{ fontSize: 24, fontWeight: 700, color: "#1a1a2e", margin: 0 }}>{t("groups.title")}</h1>
-        <button
-          type="button"
-          onClick={() => navigate("/")}
-          style={{ padding: "8px 16px", borderRadius: 6, border: "1px solid #ddd", background: "#fff", cursor: "pointer", fontSize: 14 }}
-        >
-          ← {t("common.back")}
-        </button>
-      </header>
-
-      {error && (
-        <div style={{ background: "#fde8e8", padding: 12, borderRadius: 6, color: "#e74c3c", fontSize: 14, marginBottom: 16 }}>
-          {error}
-          <button onClick={() => setError(null)} style={{ marginLeft: 12, background: "none", border: "none", cursor: "pointer", fontWeight: 600 }}>✕</button>
-        </div>
-      )}
-
-      <div style={{ marginBottom: 20 }}>
-        <button
-          type="button"
-          onClick={() => setShowCreate(!showCreate)}
-          style={{
-            padding: "12px 24px", borderRadius: 8, border: "none",
-            background: "#1a1a2e", color: "#fff", fontSize: 15, fontWeight: 600, cursor: "pointer",
-          }}
-        >
-          {showCreate ? t("groups.cancel") : t("groups.createGroup")}
-        </button>
-      </div>
-
-      {showCreate && (
-        <form onSubmit={handleCreate} style={{
-          background: "#fff", padding: 20, borderRadius: 12, marginBottom: 24,
-          boxShadow: "0 2px 8px rgba(0,0,0,0.06)", display: "flex", flexDirection: "column", gap: 14,
-        }}>
-          <div style={{ display: "flex", flexDirection: "column", gap: 6 }}>
-            <label style={{ fontSize: 14, fontWeight: 600, color: "#555" }}>{t("groups.groupName")}</label>
-            <input
-              type="text"
-              value={newName}
-              onChange={(e) => setNewName(e.target.value)}
-              placeholder={t("groups.groupNamePlaceholder")}
-              style={{ padding: "10px 12px", borderRadius: 6, border: "1px solid #ddd", fontSize: 16, outline: "none" }}
-              required
-            />
-          </div>
-          <div style={{ display: "flex", flexDirection: "column", gap: 6 }}>
-            <label style={{ fontSize: 14, fontWeight: 600, color: "#555" }}>{t("groups.description")} ({t("common.optional")})</label>
-            <textarea
-              value={newDesc}
-              onChange={(e) => setNewDesc(e.target.value)}
-              placeholder={t("groups.descriptionPlaceholder")}
-              rows={3}
-              style={{ padding: "10px 12px", borderRadius: 6, border: "1px solid #ddd", fontSize: 15, outline: "none", resize: "vertical" }}
-            />
-          </div>
-          <button
-            type="submit"
-            disabled={creating || !newName.trim()}
-            style={{
-              padding: "10px 20px", borderRadius: 8, border: "none",
-              background: "#1a1a2e", color: "#fff", fontSize: 15, fontWeight: 600,
-              cursor: creating ? "default" : "pointer", opacity: creating ? 0.6 : 1, alignSelf: "flex-start",
-            }}
-          >
-            {creating ? t("common.loading") : t("groups.create")}
-          </button>
-        </form>
-      )}
-
-      {loading ? (
-        <p style={{ textAlign: "center", color: "#888", padding: 40 }}>{t("common.loading")}</p>
-      ) : groups.length === 0 ? (
-        <div style={{ textAlign: "center", padding: 40, color: "#888" }}>
-          <p style={{ fontSize: 16, marginBottom: 8 }}>{t("groups.noGroups")}</p>
-          <p style={{ fontSize: 14 }}>{t("groups.noGroupsHint")}</p>
-        </div>
-      ) : (
-        <div style={{ display: "flex", flexDirection: "column", gap: 12 }}>
-          {groups.map((group) => (
-            <div
-              key={group.id}
-              onClick={() => navigate(`/groups/${group.id}`)}
-              style={{
-                background: "#fff", padding: 20, borderRadius: 12, cursor: "pointer",
-                boxShadow: "0 2px 8px rgba(0,0,0,0.06)", transition: "box-shadow 0.2s",
-                display: "flex", justifyContent: "space-between", alignItems: "center",
-              }}
-              onMouseEnter={(e) => (e.currentTarget.style.boxShadow = "0 4px 16px rgba(0,0,0,0.1)")}
-              onMouseLeave={(e) => (e.currentTarget.style.boxShadow = "0 2px 8px rgba(0,0,0,0.06)")}
-            >
-              <div>
-                <h3 style={{ margin: 0, fontSize: 18, fontWeight: 600, color: "#1a1a2e" }}>{group.name}</h3>
-                {group.description && (
-                  <p style={{ margin: "6px 0 0", fontSize: 14, color: "#666" }}>{group.description}</p>
-                )}
-                <p style={{ margin: "8px 0 0", fontSize: 13, color: "#999" }}>
-                  {group.member_count} {t("groups.members")} · {t("groups.admin")}: {group.admin_email}
-                </p>
-              </div>
-              <span style={{ fontSize: 20, color: "#ccc" }}>→</span>
-            </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

@@ -241,6 +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>
@@ -248,6 +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>

frontend/src/types/group.ts

@@ -1,109 +0,0 @@
-/** Types for reading groups, group books, sections, and schedules */
-
-export interface ReadingGroup {
-  id: number;
-  name: string;
-  description: string;
-  admin: number;
-  admin_email: string;
-  member_count: number;
-  created_at: string;
-  updated_at: string;
-}
-
-export interface ReadingGroupDetail {
-  id: number;
-  name: string;
-  description: string;
-  admin: number;
-  admin_email: string;
-  members: GroupMembership[];
-  created_at: string;
-  updated_at: string;
-}
-
-export interface GroupMembership {
-  id: number;
-  user: number;
-  user_email: string;
-  user_username: string;
-  role: "admin" | "member";
-  joined_at: string;
-}
-
-export interface GroupBook {
-  id: number;
-  title: string;
-  status: "active" | "replaced";
-  ebook: {
-    id: number;
-    title: string;
-    author: string;
-    filename: string;
-    format: string;
-    page_count: number;
-    file_size: number;
-    cover_image: string | null;
-    created_at: string;
-  };
-  uploaded_by: number;
-  uploaded_by_email: string;
-  section_count: number;
-  created_at: string;
-  updated_at: string;
-}
-
-export interface Section {
-  id: number;
-  title: string;
-  order: number;
-  start_chapter_index: number;
-  end_chapter_index: number;
-  estimated_reading_minutes: number;
-  created_at: string;
-}
-
-export interface GroupBookDetail extends GroupBook {
-  sections: Section[];
-  schedules: ReadingSchedule[];
-}
-
-export interface ReadingSchedule {
-  id: number;
-  meeting_number: number;
-  week_date: string;
-  section_ids: number[];
-  section_details: Section[];
-  created_at: string;
-}
-
-export interface MemberProgress {
-  id: number;
-  user: number;
-  user_email: string;
-  user_username: string;
-  current_section: number | null;
-  current_section_title: string | null;
-  completed_sections: number[];
-  updated_at: string;
-}
-
-export interface CreateGroupPayload {
-  name: string;
-  description?: string;
-}
-
-export interface AddMemberPayload {
-  user_id: number;
-}
-
-export interface CreateGroupBookPayload {
-  ebook_id: number;
-  title?: string;
-}
-
-export interface AdjustSectionsPayload {
-  operation: "merge" | "split";
-  section_ids: number[];
-  split_at?: number;
-}

packages/shared/src/types.ts

@@ -217,46 +217,98 @@ export interface ApiError {
   [key: string]: unknown;
 }
 
-// ---- Reading Groups ----
+// ---- Groups ----
 
-export interface ReadingGroup {
+export type GroupRole = "admin" | "member";
+
+export type JoinRequestStatus = "pending" | "approved" | "rejected";
+
+export interface GroupListItem {
   id: number;
   name: string;
   description: string;
-  admin: number;
-  admin_email: string;
+  created_by: number;
   member_count: number;
+  user_role: GroupRole | null;
   created_at: string;
   updated_at: string;
 }
 
-export interface GroupMembership {
+export interface GroupMember {
   id: number;
-  user: number;
+  user_id: number;
   user_email: string;
   user_username: string;
-  role: "admin" | "member";
+  role: GroupRole;
   joined_at: string;
 }
 
-export interface GroupBookSummary {
+export interface GroupDetail {
   id: number;
-  title: string;
-  status: "active" | "replaced";
-  section_count: 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 SectionSummary {
-  id: number;
-  title: string;
-  order: number;
-  estimated_reading_minutes: number;
+export interface CreateInvitePayload {
+  max_uses?: number;
 }
 
-export interface ReadingScheduleEntry {
+export interface JoinRequest {
   id: number;
-  meeting_number: number;
-  week_date: string;
-  section_ids: 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

@@ -117,11 +117,15 @@ export const API_ENDPOINTS = {
   groups: {
     list: "/api/groups/",
     detail: (id: number) => `/api/groups/${id}/`,
-    books: (groupId: number) => `/api/groups/${groupId}/books/`,
-    bookDetail: (groupId: number, bookId: number) => `/api/groups/${groupId}/books/${bookId}/`,
-    detectSections: (groupId: number, bookId: number) => `/api/groups/${groupId}/books/${bookId}/detect-sections/`,
-    adjustSections: (groupId: number, bookId: number) => `/api/groups/${groupId}/books/${bookId}/adjust-sections/`,
-    schedule: (groupId: number, bookId: number) => `/api/groups/${groupId}/books/${bookId}/schedule/`,
-    progress: (groupId: number, bookId: number) => `/api/groups/${groupId}/books/${bookId}/progress/`,
+    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;