# LangChain fixes tool-call replay and subagent identity

Two agent-library patches address how tool calls and interrupted subagents are restored. Retrospective brief for 15:00–15:59 UTC on 29 September 2026.

## The Anthropic integration preserves invalid tool calls on replay

The langchain-anthropic 1.7.5 patch serializes invalid tool calls as tool-use blocks when replaying a conversation. This changes how the integration reconstructs tool-call history for Anthropic model requests. The same release includes Sonnet 5.5 compatibility, already noted in the preceding core release. 

[langchain-ai/langchain langchain-anthropic==1.7.5 release notes](https://github.com/langchain-ai/langchain/releases/tag/langchain-anthropic%3D%3D1.7.5)

## The QuickJS integration preserves subagent identity through interrupts

The langchain-quickjs 0.3.8 patch preserves subagent identity when replaying interrupts. Agent applications that resume interrupted execution need the replay to refer to the same subagent; this release explicitly addresses that behavior. 

[langchain-ai/deepagents langchain-quickjs==0.3.8 release notes](https://github.com/langchain-ai/deepagents/releases/tag/langchain-quickjs%3D%3D0.3.8)