AI Workflow / LINE Official Account / Group Archiving

How to Auto-Archive Data Scattered Across LINE Groups Every Day

This article uses Mika as a demonstration case. Mika is the first version I built for demo purposes. What you actually take away is the architecture: connect your own LINE official account to groups, collect messages, images, PDFs, and files first, then hand everything to your Agent for organization.

LINE groups as AI workflow entry points: summary card
Mika in the illustration is a demo character. You can replace it with your own course assistant, community secretary, or company helper.

One-Page Summary

This workflow addresses a very everyday problem: people share links, photos, meeting notes, and PDFs in group chats. Everyone can see them in the moment, but a few days later when you need to find something, all you can do is scroll up and hope someone remembers. Mika is just the demo name. What you are actually building is your own LINE AI assistant.

Step 1: Collect

Add your own official account to regular LINE groups. When new messages arrive, LINE proactively pushes the events to your receiving service through a webhook.

Step 2: Fetch Attachments

Images, videos, audio, and files are retrieved by messageId and stored in folders organized by group and date.

Step 3: Organize

An Agent runs once a day to update group names, fetch missing attachments, and flag messages that need a human response.

Core Principle Collect data reliably first, then hand the organization rules to your Agent. The assistant can be called Mika, a course TA, a community secretary, or a company helper. The name does not matter. The architecture is what you take away.
No coding required on your end If you do not write code, treat this article as a task list and hand it to Codex, another Agent, or a technical partner. The decisions that belong to you are: which groups to monitor, where to store the data, who needs to be notified, and which situations must never trigger an automatic reply.
Collect data first, do not rush to have AI reply
The first step is getting messages, images, and files into a traceable location. Auto-reply belongs to a later stage, handled only in explicitly authorized contexts.

Minimum Viable Workflow

01LINE Group

Everyone continues sharing messages, images, PDFs, and links as usual.

02Official Account

Your LINE AI assistant receives new message events after activation through the webhook.

03Archive Folder

Text is stored immediately; images and attachments are fetched in a separate pass.

04Agent Organizes

Daily automatic run updates group names, fetches missing attachments, and identifies messages awaiting a response.

05Human Decides

The responsible person is notified only when something important appears. The system never replies on anyone's behalf.

LINE group → your official account webhook → receive message events → fetch images and attachments → write to archive folder → Agent organizes daily → notify human only when something important arrives
Two-Phase Design Phase one is a passive collection and archiving layer: real-time receipt, deferred organization, folders separated by group. The default mode is dry-run: messages are collected and archived normally, but the bot does not reply in LINE groups, even when someone mentions the assistant. Phase two, a lightweight TA that replies, comes later and only in clearly authorized contexts.
First Responsibility of the Webhook The receiving service must acknowledge LINE quickly by returning 200 OK. Return 200 only after the event has been successfully written to the database or cloud folder. If writing fails, return an error (5xx) so LINE has the opportunity to redeliver. Do not perform long summaries, AI calls, or bulk uploads at receipt time. Those tasks belong to a background job or the nightly organization run.
Does This Use a Lot of Tokens? Receiving messages and running the daily download-and-archive pass are pure programming tasks. They make no AI calls and consume no AI tokens. Tokens are used only when you ask an Agent to read this batch of data for summaries, analysis, or draft replies. Keep the Agent run low-frequency, once a day, and the cost stays very manageable.

Why Not Use the Personal LINE App

LINE offers two paths. An official account uses the Messaging API webhook, which can join groups and receive new events after activation. The personal LINE app and its desktop chat history require screen-reading or OCR, a centaur-style approach. The two mechanisms are fundamentally different. Confirm which path you are on before proceeding.

What This Can Do

Join groups, receive new messages after activation, archive by groupId, use the Group Summary API to retrieve human-readable group names, and fetch images and attachments.

What to Avoid Claiming

This approach does not read your personal LINE app, and it cannot backfill message history from before the webhook was activated. Whether the assistant replies inside a group requires a separate design decision.

If You Are Not Familiar with the LINE Console

You can authorize Codex or another Agent to operate your screen during the current session to help confirm the official account, Messaging API, webhook, and group join settings. The block below is authorization language you can speak directly to an Agent. You do not need to understand every setting yourself.

I am not familiar with the LINE Developers console. I authorize the Agent to operate my screen during this session to create or confirm the official account, enable the Messaging API, configure the webhook, and confirm that group joining is enabled. Do not paste tokens into chat. Write them directly to the local config file .env or to the system Keychain.
Choose the Right Official Account First

You can create a dedicated official account or use an existing one. If you already have a brand official account, confirm the impact before changing the webhook or Messaging API settings. Do not touch an active account without being certain of the scope.

Inform Group Members First

Before adding the assistant to a group, let members know it will archive new messages and attachments after activation, and clarify that the purpose is organization and reminders, not surveillance or automatic replies on anyone's behalf.

Never Expose or Sync Tokens

Your channel access token and channel secret are the credentials for your LINE official account, equivalent to a password. Do not paste them into chat, do not write them into a notes app, and do not upload them to GitHub or any code platform. For long-term storage, use a local config file (.env) or the system Keychain.

Keep Data and Code Separate

Credentials stay on the local machine only. Messages, images, and PDFs go to the archive folder designated by your team, synced according to your team's own rules.

Automatic daily organization run
The daily run is for updating group names, fetching images, and listing messages awaiting a response. It does not auto-reply in LINE.
Do Not Touch Live Services Without a Plan If you already have a live relay, database, persistent sync, or established data write path, list the scope of impact and a rollback method before making any changes. Until that is confirmed, limit actions to reading configuration and writing recommendations. Do not deploy, disable, move, or change secrets.
Keep Reliability Layers Separate Quick tunnels such as ngrok are suitable for initial verification only. When your local machine sleeps or shuts down, the webhook cannot receive events. Any scenario that requires sustained message collection needs a cloud relay, not a locally hosted service presented as a reliable deliverable. My own setup uses a cloud relay: the cloud layer receives and stores events, and the local machine syncs new events down once a day for organization.
LINE Redelivers Failed Events, With Conditions The following detail is for engineers running their own webhook. LINE webhook redelivery must be manually enabled in the Developers Console. Once enabled, it only retries within a limited window. If your server consistently fails to respond correctly, LINE stops retrying. After redelivery, use the event timestamp to determine order. My cloud relay runs on Cloudflare. A cloud relay is not a long-term database; it must connect to a system that can store data persistently, such as a database or a cloud folder. Return 200 only after the event has been successfully written.

How Group Names and Attachments Are Organized

Initially, LINE webhooks only reliably provide the unique identifier LINE assigns to each group: the groupId. Using a raw ID as a folder name is not human-readable. The maintenance script calls the LINE Group Summary API to retrieve the group name, prepending the readable name and appending the ID suffix to avoid collisions between groups with identical names.

Group names should be human-readable
All names shown are simulated. No real group names appear in the public version.
Before

LINE-group-g1234567__g1234567

After

Sample-Group-Name__g1234567

Images, videos, audio, and files are retrieved using the unique messageId LINE assigns to each message. Once fetched, everything goes into folders named by group and date, making them easy to find later. A typical path looks like groups/GroupName__suffix/media/YYYY-MM-DD/, and the Markdown log is updated with human-readable links.

What This Article Is Good For

The point of this approach is to let you build your own LINE AI assistant: connecting data scattered across groups into your workflow, collecting it reliably, organizing it, and getting notified. It works best for courses, communities, small teams, and project collaborations that already run on LINE groups.

  • Social post: use the real demo case to illustrate the "collect first, organize second" logic.
  • Website article: treat it as a construction blueprint for building your own LINE AI assistant.
  • Skill or checklist: provide the workflow, configuration guide, and .env.example so readers can build their own version, with no tokens included.
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