LINE Flex Message & Reliability Skill

This skill extends Claude's ability to design high-quality, brand-consistent LINE Flex Messages and implement reliable messaging workflows.

Core Capabilities

1. Advanced Flex Layouts: Precise control over nested boxes, dynamic widths, and complex UI patterns (e.g., flight tickets, product lists).
2. Video Integration: Guidelines and templates for embedding video components in the hero block.
3. Reliable Communication: Implementing X-Line-Retry-Key and exponential backoff strategies to handle 429/5xx errors.

Workflow Patterns

1. Designing a Complex Flex Message

1. Identify Layout: Determine if it's a single Bubble or a Carousel.
2. Component Mapping: Map UI elements to Flex blocks (Header, Hero, Body, Footer).
3. Refine Nesting: Use scripts/flex_builder.py or reference references/flex-elements.md to create multi-layer box nesting.
4. Add Actionability: Ensure all buttons and images have correct action definitions.

2. Implementing API Retries

1. Generate Key: Use scripts/flex_builder.py to generate a unique X-Line-Retry-Key.
2. Header Injection: Always include the retry key in the first request for supported APIs (Push, Multicast, etc.).
3. Error Handling: Follow the decision matrix in references/retry-policy.md:
   • 429/5xx/Timeout: Retry with exponential backoff.
   • 409: Log as "already accepted" and proceed.
   • 2xx: Success.

Resources

• Flex Elements & Layout Guide: Detailed component specifications.
• Flex Video Guide: Requirements and examples for video embedding.
• Retry & Reliability Policy: Strategic guide for headers and error handling.
• Flex Builder Script: Python utility for generating complex Flex JSON and retry headers.

Layout Patterns Examples

• Product List: Use nested horizontal boxes for image + text rows.
• Video Hero: Mega/Giga sized bubbles with type: video in hero block.
• Carousel: Side-scrolling bubbles for browsing multiple items.

Quality Standards

• Consistency: Use spacing and margin consistently across bubbles.
• Responsiveness: Use wrap: true for text and test layouts with different font sizes.
• Stability: Never send high-frequency messages without a retry strategy.