LangChain.js @langchain/openai 1.6.0: explicit prompt cache options + content-block breakpoints
LangChain.js shipped `@langchain/[email protected]` on 2026-09-27: ports explicit prompt-cache options across Chat Completions and Responses, preserves content-block breakpoints, and maps cache-write usage to `cache_creation`. A same-tag fix serializes `promptCacheRetention: "in-memory"` as API-legal `"in_memory"` and unifies precedence (per-call → modelKwargs → constructor); Chat Completions no longer drops modelKwargs.
- •Shipped: @langchain/[email protected] / npm 1.6.0
- •Explicit prompt cache options + content-block breakpoints; cache-write → cache_creation (PR #11232)
- •Fix: serialize in-memory as in_memory; precedence per-call > modelKwargs > constructor (PR #11735)
- •Install: npm i @langchain/[email protected]
- •Follow-on: @langchain/[email protected] bumps this dependency the same day

