[techjacker]

Summary v0.3.0

• Add transparent retry with exponential backoff for transient LLM errors (Bedrock ServiceUnavailableException, throttling, network) using LangChain's built-in .withRetry() on the chat model
• Add llmRetryAttempts config option (default: 3, set to 0 to disable) so consumers can tune retry behavior
• Add specific error message for ServiceUnavailableException when retries are exhausted, replacing the generic "Unexpected error" output

Problem

Bedrock intermittently returns ServiceUnavailableException (503) during the LangChain ReAct agent loop. This kills the entire agent.invoke() call, losing all accumulated agent state (tool calls, reasoning steps). The error falls through to a generic catch-all with an unhelpful message:

TEST_FAILED: Unexpected error during agent execution (ServiceUnavailableException).
  Error: Bedrock is unable to process your request.
  Suggestion: This may be a transient issue. Check the error above and retry.

The existing test-level retry (maxAttempts) restarts the entire test from scratch — wasteful for a transient infrastructure hiccup on a single LLM call mid-conversation when test suites can take 45 mins to run.

Solution

Retry at the LLM call level using model.withRetry(), which is available on all LangChain Runnable instances. This is the optimal layer because:

1. Preserves agent state — a transient 503 on one LLM call gets retried without losing the entire multi-step conversation
2. Exponential backoff built-in — LangChain's RunnableRetry handles backoff internally
3. Fail-fast for non-transient errors — the onFailedAttempt callback re-throws auth errors, validation errors, etc. immediately
4. Zero consumer config changes needed — the default llmRetryAttempts: 3 kicks in automatically

Error classification (isTransientError)

Retries only for errors classified as transient:

• ServiceUnavailableException (Bedrock 503)
• ThrottlingException, 429, rate limit
• ModelStreamErrorException, overloaded
• ECONNRESET, ETIMEDOUT, socket hang up

All other errors (401, API key, validation, recursion limit) fail immediately.

Misc Extra Fixes

App prints dynamic version from obtained from package.json.

[elonsalfati]

Should we create custom errors instead of searching for text within the error message?

[techjacker]

done with be8d653