agentsop-state-reducer

What problem does it solve?

This Skill prevents LangGraph from crashing when multiple parallel branches (or multi-agent writes) update the same state key in a single step.

Core Features & Use Cases

• State-key merge contracts: Teaches how to declare per-key reducer semantics so parallel writes merge instead of throwing InvalidUpdateError.
• Reducer selection playbook: Maps common key types (messages, counters, lists) to the right reducer patterns like add_messages and operator.add.
• Test-and-document workflow: Guides you to enumerate writers per key, pick a reducer, validate with a probe test, and document the contract in your state schema.

Quick Start

Ask the Skill for the correct reducer to apply after you paste your LangGraph state schema and describe which nodes write to the same key in parallel.