# Langchain Chains

> LangChain chain composition including SequentialChain, RouterChain, and LCEL patterns

- Skill: `a5c-ai/langchain-chains` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add a5c-ai/langchain-chains`
- Raw SKILL.md: https://api.skillmd.com/api/skills/a5c-ai/langchain-chains/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: a5c-ai (https://skillmd.com/u/a5c-ai)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/a5c-ai/langchain-chains

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# LangChain Chains Skill

## Capabilities

- Compose LangChain chains using LCEL (LangChain Expression Language)
- Implement sequential chain patterns
- Design router chains for conditional logic
- Create parallel execution chains
- Handle chain fallbacks and retries
- Implement streaming chains

## Target Processes

- dialogue-flow-design
- chatbot-design-implementation

## Implementation Details

### Chain Patterns

1. **LCEL Pipelines**: Modern composition with | operator
2. **SequentialChain**: Linear chain execution (legacy)
3. **RouterChain**: Conditional routing based on input
4. **RunnableParallel**: Parallel execution branches
5. **RunnableBranch**: Conditional branching

### Configuration Options

- Input/output key mapping
- Error handling strategies
- Retry configuration
- Streaming settings
- Batch processing options

### Best Practices

- Use LCEL for new implementations
- Implement proper input/output schemas
- Add fallback chains for resilience
- Use streaming for long operations

### Dependencies

- langchain-core
- langchain