LINE MINI App

Do not answer LINE MINI App questions from memory — LINE updates APIs frequently and training data is unreliable. Always consult the references below.

LINE MINI App is a web app platform built on LIFF that runs inside LINE.

Workflow

1. Read references/guidelines.md first (policy rules, specs, constraints)
2. Load the relevant reference for the feature being worked on
3. For architecture or design choices, consult references/experts.md
4. When reviewing, cross-check code against specs (token lifecycle, message limits, scope requirements, template naming, IAP order flow)

Environment Variables

LIFF_ID=LIFF app ID (LINE MINI App runs on LIFF)
LINE_CHANNEL_ACCESS_TOKEN=Stateless channel access token (Service Messages, IAP)
LINE_LOGIN_CHANNEL_ID=LINE Login Channel ID (server-side verification)
LINE_LOGIN_CHANNEL_SECRET=Channel secret (server-side only)

MINI App vs LIFF

All LIFF APIs are available in MINI App context (LIFF browser). See Key Constraints for external browser limitations.

Service Messages

User opens MINI App → liff.getAccessToken() → Issue notification token → Send service messages (max 5)

• Token validity: 1 year, max 5 messages per token
• LIFF access token is revoked when user closes the MINI App — issue notification token before user leaves

Full API specs, template structure, error codes → references/service-messages.md

Common Profile Quick Fill

const result = await liff.$commonProfile.get(scopes, { formatOptions });
liff.$commonProfile.fill(result.data);  // auto-fill <input data-liff-autocomplete="...">

Full API specs, scopes, dummy data → references/common-profile.md

In-App Purchase

Japan only. Consumable digital content only. Requires LIFF SDK ≥ 2.26.0, LINE ≥ 15.6.0, LIFF browser.

Purchase flow (client + server), dev guidelines, error codes → references/in-app-purchase.md

Key Constraints

• MINI App runs on LIFF — all LIFF constraints apply (Endpoint URL, init order, environment differences)
• Stateless channel access tokens only — long-lived and v2.1 tokens cannot be used for MINI App channels
• Channel consent simplification only skips openid — profile, email, chat_message.write require verification screen; needs LIFF SDK v2.13.x+, verified MINI App
• Custom share messages must use Bubble container (not Carousel); actions only on buttons and footer
• External browser: liff.init() doesn't auto-login (use withLoginOnExternalBrowser: true); sendMessages, openWindow, closeWindow, iap.* unavailable
• LINE Pay terminated in Japan (April 30, 2025) — verify current availability at LINE Pay docs
• IAP auth differs by endpoint: reserve uses user token, webhook history uses channel token; webhook uses signature verification, not IP restriction
• Channel cannot be moved to another provider after creation; user IDs differ per provider

Reference Index

SDK & Tools

• LINE MINI App is built on LIFF SDK: @line/liff
• Quick Fill plugin: @line/liff-common-profile-plugin
• Scaffold: npx @line/create-liff-app
• LINE MINI App Playground: miniapp.line.me/lineminiapp_playground — online MINI App API testing