When to use this skill

Use this skill when you need to:

• Support multiple LINE groups with independent configurations

• Implement group isolation for data and settings

• Handle group join/leave events automatically

• Manage per-group member lists and schedules

• Design scalable multi-tenant bot architecture

• Migrate from single-group to multi-group system

How to use it

Core Principles

• Group Isolation: Each group has completely separate data

• Automatic Registration: Groups auto-register when bot joins

• Independent Scheduling: Each group can have different broadcast times

• Context-Aware: All operations require group_id context

Data Architecture

1. Group Registry

List of all registered groups

group_ids = [ "C1234567890abcdef1234567890abcdef", "C9876543210fedcba9876543210fedcba" ]

2. Per-Group Member Data

groups = { "C群組ID1": { "1": ["Alice", "Bob"], "2": ["Charlie"], "3": ["David", "Eve"] }, "C群組ID2": { "1": ["Frank"], "2": ["Grace", "Henry"] } }

3. Per-Group Schedules

group_schedules = { "C群組ID1": { "days": "mon,wed,fri", "hour": 17, "minute": 0 }, "C群組ID2": { "days": "tue,thu", "hour": 9, "minute": 30 } }

4. Per-Group Custom Messages (Optional)

group_messages = { "C群組ID1": { "reminder_template": "🗑️ 今天輪到 {members} 收垃圾！" }, "C群組ID2": { "reminder_template": "📢 {members} 請記得收垃圾喔！" } }

Implementation Patterns

1. Extracting Group ID from Event

def get_group_id_from_event(event): """ Extract group ID from LINE event

Returns:
    str: Group ID or None if not from a group
"""
try:
    if hasattr(event.source, 'group_id'):
        return event.source.group_id
    else:
        # Private chat, not a group
        return None
except Exception as e:
    print(f"Failed to get group ID: {e}")
    return None

2. Group Join Event Handler

@handler.add(JoinEvent) def handle_join(event): """ Auto-register group when bot joins """ group_id = get_group_id_from_event(event)

if group_id and group_id not in group_ids:
    # Register new group
    group_ids.append(group_id)
    save_group_ids()
    
    # Initialize empty group data
    groups[group_id] = {}
    save_groups()
    
    # Send welcome message
    welcome_msg = (
        "👋 感謝加入垃圾輪值提醒 Bot！\n\n"
        "📝 請使用以下指令設定：\n"
        "@time 18:00 - 設定推播時間\n"
        "@day mon,wed,fri - 設定推播日期\n"
        "@week 1 小明,小華 - 設定第1週成員\n\n"
        "使用 @help 查看完整指令列表"
    )
    
    messaging_api.reply_message(
        ReplyMessageRequest(
            reply_token=event.reply_token,
            messages=[TextMessage(text=welcome_msg)]
        )
    )
    
    print(f"✅ New group registered: {group_id}")

3. Group Leave Event Handler

@handler.add(LeaveEvent) def handle_leave(event): """ Clean up when bot leaves a group """ group_id = get_group_id_from_event(event)

if group_id:
    # Remove from group list
    if group_id in group_ids:
        group_ids.remove(group_id)
        save_group_ids()
    
    # Clean up group data
    if group_id in groups:
        del groups[group_id]
        save_groups()
    
    # Remove schedule
    if group_id in group_schedules:
        del group_schedules[group_id]
        save_group_schedules(group_schedules)
        
        # Remove scheduled job
        job_id = f"reminder_{group_id}"
        if scheduler.get_job(job_id):
            scheduler.remove_job(job_id)
    
    print(f"🗑️ Group cleaned up: {group_id}")

4. Context-Aware Operations

Always pass group_id to functions:

def get_current_group(group_id): """Get current week members for specific group""" if group_id not in groups: return []

group_data = groups[group_id]
# ... calculation logic
return current_members

def get_member_schedule(group_id): """Get schedule info for specific group""" if group_id not in groups: return { "total_weeks": 0, "current_week": 1, "group_id": group_id, "current_members": [] }

# ... schedule logic
return schedule_info

5. Command Handler with Group Context

@handler.add(MessageEvent, message=TextMessageContent) def handle_message(event): text = event.message.text.strip() group_id = get_group_id_from_event(event)

# Require group context
if not group_id:
    reply_text = "❌ 此 Bot 僅支援群組使用"
    messaging_api.reply_message(
        ReplyMessageRequest(
            reply_token=event.reply_token,
            messages=[TextMessage(text=reply_text)]
        )
    )
    return

# Process commands with group context
if text.startswith('@'):
    parts = text[1:].split()
    command = parts[0].lower()
    
    if command == 'schedule':
        # Show THIS group's schedule
        reply_text = get_schedule_info(group_id)
    elif command == 'members':
        # Show THIS group's members
        reply_text = get_member_schedule_summary(group_id)
    # ... more commands

Migration Strategy

From Single Group to Multi-Group

Step 1: Add Legacy Group Support

Convert old single-group data to multi-group format

def migrate_to_multi_group(): global groups

# If groups is still a dict with week keys
if groups and '1' in groups:
    # This is old format, migrate to new
    legacy_data = groups.copy()
    groups = {
        "legacy": legacy_data
    }
    save_groups()
    print("✅ Migrated to multi-group format")

Step 2: Backward Compatible Functions

def get_current_group(group_id=None): """ Support both old and new usage

Args:
    group_id: Group ID (None for legacy mode)
"""
if group_id is None:
    # Legacy mode: use first available group
    if "legacy" in groups:
        group_data = groups["legacy"]
    elif groups:
        group_data = next(iter(groups.values()))
    else:
        return []
else:
    # New mode: use specific group
    if group_id not in groups:
        return []
    group_data = groups[group_id]

# ... rest of logic

Best Practices

Always Validate Group ID

if group_id not in groups: return error_response("Group not found")

Consistent Storage Keys Use group_id as the primary key across all dictionaries

Atomic Operations Update all related data together:

Update members

groups[group_id] = new_data save_groups()

Update schedule

group_schedules[group_id] = new_schedule save_group_schedules(group_schedules)

Group-Specific Responses Include group context in responses when helpful:

reply_text = f"✅ 已更新群組設定\n\n" reply_text += f"📊 目前有 {len(groups[group_id])} 週輪值"

Testing Multi-Group

• Create multiple test groups

• Verify data isolation between groups

• Test concurrent operations on different groups

Firestore Schema for Multi-Group

bot_config/ groups/ { "C群組ID1": { "1": ["Alice", "Bob"], "2": ["Charlie"] }, "C群組ID2": { "1": ["David"], "2": ["Eve", "Frank"] } }

group_schedules/ { "C群組ID1": { "days": "mon,wed,fri", "hour": 17, "minute": 0 } }

Common Pitfalls

❌ Don't: Assume single group

current_members = get_current_group() # Which group?

✅ Do: Always specify group

current_members = get_current_group(group_id)

❌ Don't: Share data across groups

base_date = date.today() # Global for all groups

✅ Do: Store per-group if needed

group_base_dates = { group_id: date.today() }

Reference Patterns

See existing implementation in:

• main.py : Multi-group command handlers

• firebase_service.py : Group data storage

• README.md : Multi-group usage examples