LangChain4j CDI 1.4.0 Released
LangChain4j CDI 1.4.0 is available. This release brings thinking capture for AI services, improvements to GenAI telemetry semantics, a full migration to MCP Java 1.x, and a module-system fix for build-time extensions.
What's New
Thinking Capture for AI Services
AI service methods can now capture the model's internal reasoning — the "thinking" tokens emitted by reasoning models like Claude. This is exposed via a new listener/guardrail hook, so you can observe or act on the thought chain alongside the final response.
GenAI Telemetry Improvements
The langchain4j-cdi-telemetry module now follows the OpenTelemetry GenAI Semantic Conventions more completely, including correct exception semantics. If a model call raises an error, the resulting span is now attributed according to the GenAI spec rather than the generic HTTP conventions.
MCP Java 1.x Migration
The MCP server module tree has been migrated to MCP Java 1.x (mcpjava 1.x). This is a breaking change within the MCP sub-tree: package names and some API surface were reorganised as part of the 1.x overhaul. If you depend on langchain4j-cdi-mcp-* directly, check the MCP Server guide and the upstream MCP Java changelog for the new package names.
JPMS Split-Package Fix
A split-package conflict in the build-compatible extension (langchain4j-cdi-build-compatible-ext) has been resolved. Applications running on runtimes that enforce Java module boundaries (JPMS) -- such as Quarkus with strict module mode -- will no longer encounter split-package errors at startup.
Dependency Upgrades
| Dependency | From | To |
|---|---|---|
| LangChain4j | 1.18.0 | 1.19.0 |
resteasy-bom |
6.2.16.Final | 6.2.17.Final |
yasson |
3.0.4 | 3.0.5 |
cargo-maven3-plugin |
1.10.27 | 1.10.28 |
apache-maven |
3.9.11 | 3.9.16 |
maven-wrapper |
3.3.2 | 3.3.4 |
Upgrading
Update your dependency version to 1.4.0:
<properties>
<langchain4j-cdi.version>1.4.0</langchain4j-cdi.version>
</properties>
If you use the MCP server module, review the MCP Server documentation and verify your import statements after the mcpjava 1.x package rename.
Contributors
Thank you to everyone who contributed to this release:
- @ehsavoie -- thinking capture, MCP migration, JPMS fix, and release coordination
- @TheEliteGentleman -- telemetry improvements and documentation
- @dependabot -- automated dependency upgrades
Full release notes and the complete list of merged pull requests are available on the GitHub Releases page.
