Fixing `agentevals` Error: Missing `@langchain/openai` Export

Hey Folks, Let's Tackle This agentevals Mystery Together!

Alright, guys, let’s dive straight into a problem that's been tripping up some of us who are working with LangChain and trying to get our AI agents properly evaluated. If you’ve hit a nasty SyntaxError involving agentevals and a missing _convertMessagesToOpenAIParams export from @langchain/openai, you're definitely not alone. It's super frustrating when you're trying to leverage cutting-edge tools like agentevals to rigorously test your LangChain agents, only to be stopped dead in your tracks by what seems like a cryptic internal error. We’re specifically talking about issues encountered when trying to run examples like the Trajectory Strict Match Evaluation, which is a fantastic way to ensure your agents are following precise interaction paths. This _convertMessagesToOpenAIParams issue is more than just a minor hiccup; it completely halts your development workflow, much like trying to assemble a complex piece of furniture only to find a critical screw missing from the box. The whole point of using agentevals is to give developers the confidence that their AI agents are performing exactly as intended, allowing us to catch any deviations or unexpected behaviors early on. When the evaluation tool itself is throwing an error, it creates a significant roadblock. This scenario perfectly highlights the ongoing challenges of working within rapidly evolving technology ecosystems where dependency management and API stability are constant considerations. We're going to break down exactly why this error occurs, look at the specific versions of @langchain/core, @langchain/langgraph, @langchain/openai, and agentevals that are causing the conflict, and, most importantly, provide you with clear, actionable steps to get your LangChain evaluations back on track. So, grab a coffee, and let's unravel this together and get you back to building and evaluating those awesome LangChain agents!

Decoding the _convertMessagesToOpenAIParams Error in agentevals

Let’s get into the nitty-gritty of the _convertMessagesToOpenAIParams error that's been causing headaches for developers using agentevals with LangChain. The exact error message you're likely seeing is a SyntaxError: The requested module '@langchain/openai' does not provide an export named '_convertMessagesToOpenAIParams'. What does this really mean in plain English, guys? Well, it tells us that the agentevals library is trying to import and use a specific function, _convertMessagesToOpenAIParams, from the @langchain/openai package. However, the version of @langchain/openai you currently have installed simply does not expose this function anymore. It’s like trying to find a specific book in a library, but the library has undergone a renovation, and that book has either been moved, renamed, or removed entirely from the collection. The stack trace clearly points to file:///.../node_modules/openevals/dist/utils.js, indicating that the core issue lies within agentevals (or its underlying openevals dependency) attempting to access this now-defunct internal export. The specific dependencies you've listed – "@langchain/core": "1.0.5", "@langchain/langgraph": "1.0.1", "@langchain/openai": "1.1.0", "agentevals": "0.0.6" – are crucial pieces of the puzzle. This particular combination suggests that agentevals version 0.0.6 was developed with an expectation that the _convertMessagesToOpenAIParams function would be available in @langchain/openai. However, @langchain/openai at version 1.1.0 has evolved past this point. This isn't just a minor bug; it signifies a fundamental breaking change in the way these libraries interact. The core problem boils down to a classic dependency mismatch scenario, common in rapidly evolving open-source projects. The SyntaxError from Node.js is incredibly precise: it's not a runtime error, but a module resolution error, meaning the export literally cannot be found when agentevals attempts to load it. This situation stops your code from even starting, making it especially frustrating. Understanding this exact error and its origin is the critical first step to getting your AI agent evaluation workflow back on track.

The Root Cause: LangChain's Evolution and Internal Changes

The smoking gun behind this agentevals error is a specific change within the LangChain JS repository, which led to the removal of _convertMessagesToOpenAIParams. Guys, this isn't some conspiracy; it's a testament to how quickly frameworks like LangChain are evolving to meet new demands and improve their architecture. We can trace this back directly to a GitHub Pull Request – specifically, https://github.com/langchain-ai/langchainjs/pull/9340/files#diff-66edfb8802bae11da9a9968e0d0c1895921e5aef53ab0b9cc8fa9d77cdf60434L193. If you look at that diff, you'll see quite clearly that the _convertMessagesToOpenAIParams function was indeed removed from @langchain/openai. This is the core reason why agentevals, at its current version, can't find what it's looking for. Why would LangChain remove such a function? Typically, these changes are part of broader refactoring efforts. As a library matures, internal utilities might be consolidated, moved to a more central package like @langchain/core, or simply deemed obsolete due to architectural improvements. The key takeaway here is that _convertMessagesToOpenAIParams was likely an internal utility function, not part of the officially documented public API. Relying on such internal APIs, while sometimes convenient, carries an inherent risk because they are not guaranteed to remain stable across versions. They can change, be renamed, or be removed without a major version bump in the public-facing API, precisely because they aren't considered part of the