error.response is only populated when callerOptions.onFailedResponseHook is configured

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I added a very descriptive title to this issue.
I searched the LangGraph.js documentation with the integrated search.
I used the GitHub search to find a similar question and didn't find it.
I am sure that this is a bug in LangGraph.js rather than my code.
The bug is not resolved by updating to the latest stable version of LangGraph (or the specific integration package).

Example Code

To reproduce:

const client = new Client({ apiUrl: "http://localhost:2024" });
try {
  await client.threads.get("nonexistent-thread");
} catch (err) {
  console.log(err.response); // undefined, even though the request failed with a real HTTP response
}

Environment: @langchain/langgraph-sdk, current main as of 2026-07-24

Error Message and Stack Trace (if applicable)

No response

Description

When an API call made through Client fails, the resulting error's .response property is undefined unless the client was configured with callerOptions.onFailedResponseHook.

This is because in libs/sdk/src/utils/async_caller.ts, HTTPError.fromResponse is called with includeResponse: !!onFailedResponseHook — the raw response is only attached as a side effect of registering that hook, which is meant for something else (e.g. logging/telemetry on failure), not for consumers who just want to inspect the response on error.

Expected behavior: There should be an explicit, independent option (e.g. callerOptions.includeResponseOnError or simply always attaching error.response) so callers can access the failed response without having to register an unrelated hook.

System Info

this is on latest right now

I'd like to take this if maintainers are happy to assign it.

I checked current main at 6ac60da; libs/sdk/src/utils/async_caller.ts is blob 22299f2, identical to the locally exercised file. An offline minimal reproduction with AsyncCaller({ maxRetries: 0 }) rejecting a real Response("missing", { status: 404 }) produced:

{"name":"HTTPError","status":404,"text":"missing","responseIsUndefined":true}

No server or provider credentials are required. I also verified there is currently no assignee, linked branch/PR, or PR referencing #2632.

Proposed focused change after assignment:

decouple response retention from onFailedResponseHook while preserving the hook and retry behavior;
add a regression asserting the thrown HTTP error retains the failed Response without configuring the hook, plus coverage that the hook path remains unchanged;
run the focused async_caller suite, SDK unit suite, build, lint, and format checks.

I will wait for assignment before changing code, per CONTRIBUTING.md.

AI assistance disclosure: I used OpenAI Codex to inspect the repository rules and current source and to run the offline reproduction. I personally reviewed the evidence, proposed scope, and this comment.

fix(sdk): always attach Response on HTTPError

fix(sdk): always attach Response on HTTPError (#2668)

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error.response is only populated when callerOptions.onFailedResponseHook is configured #2632

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error.response is only populated when callerOptions.onFailedResponseHook is configured #2632

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kinKingen commented on Aug 6, 2026

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