CallbackManager._configureSync (or .configure) to inject a
FiddlerCallbackHandler into every invocation.
Node.js only — requires @langchain/core as a peer dependency and
uses node:async_hooks (via context) for context propagation.
Uses a WeakSet to track patched modules so frozen ESM exports
are handled correctly.
Methods
constructor(client: FiddlerClient)
An initialized FiddlerClient used by the
callback handler to create spans.
async instrument(): Promise<void>
Auto-instrument by dynamically importing @langchain/core/callbacks/manager.
isInstrumented(): boolean
Check whether the instrumentor has successfully patched a
CallbackManager module.
return
true if auto-instrumentation is active.manuallyInstrument(module: CallbackManagerModule)
Manually instrument a specific @langchain/core/callbacks/manager module.
This is the recommended approach for bundled environments.
The imported
@langchain/core/callbacks/manager module.uninstrument()
Remove the patch and restore the original CallbackManager behavior.
Safe to call even if the instrumentor was never activated.