Agents in code
Debug infinite tool loop in the bounded research agent
Page 5 reproduces and repairs the characteristic failure of the bounded research agent over a fixture KB: infinite tool loop, or final answer with no citations after search.
1Learn the idea
Read
Reproduce before you repair
Do not start with a speculative fix for the bounded research agent. Force the failure on purpose, save the before output, then change one cause at a time. Retries are allowed only for transient conditions—not for bad input that will fail forever on agents-in-code.
Read
Force the failure
for (let attempt = 0; attempt <= maxRetries; attempt++) {
try { return await operation(signal); }
catch (error) {
const failure = classify(error);
if (!failure.retryable || attempt === maxRetries) throw failure;
await sleep(jitteredBackoff(attempt), signal);
}
}
throw new Error("unreachable");
Expected evidence: The agent searches once, cites kb://returns, and stops before MAX_AGENT_STEPS.. If you cannot reproduce on demand, you do not yet control the failure mode for agents-in-code.
Read
Repair with a reviewable diff
After repair, rerun the exact reproduction command. Keep the failing fixture as a regression seed for the observability page. For the bounded research agent over a fixture KB, remember the claim you are restoring: agent stops at max_steps; every claim cites a KB id or abstains.
Read
Lab notebook: reproduce on command
Store a one-command reproduction for: infinite tool loop, or final answer with no citations after search. The command should use fixture KB with 4 notes + max_steps=3 or a minimal mutant of it. Paste the failing output into notes/failure-before.txt (or your shell scrollback as copied text). After the fix, paste notes/failure-after.txt and keep both.
Retries belong only on transient faults. If the failure is bad input, a bad allowlist, or a logic bug in the bounded research agent, retrying will amplify cost without repairing trust around search a local knowledge base then produce a cited answer within a step budget.
Read
Worked judgment
Classify the failure as prevent, detect, contain, or recover—using this lab’s language, not a generic poster. For agents-in-code, the first fix should usually be detect+prevent at the boundary, because infinite tool loop, or final answer with no citations after search is cheaper to stop early than to explain in production prose.
Read
Why this stage matters for the bounded research agent
At the debugging stage for agents-in-code, the job is narrower than finishing a product demo. You are creating one progressive evidence piece about fixture KB with 4 notes + max_steps=3 that later pages inherit without redefining success. Keep that fixture small enough to inspect by hand, keep outputs copy-pasteable as text, and refuse to narrate this baseline as if it were a production SLA: single-shot LLM answer without search.
For this page specifically, success looks like before/after evidence for the characteristic failure while still centering the user decision to search a local knowledge base then produce a cited answer within a step budget. If you cannot point to a file, command, or assertion that proves that for the bounded research agent, stay on this page instead of advancing.
Glossary: tool · Glossary: structured output · Cheatsheet: production ops signals
Go deeper
Before you start
Why this matters
Describe the smallest fixture that triggers infinite tool loop. Predict the first visible symptom (exception, wrong label, silent empty success). You will compare that prediction with the reproduction below.
In the wild
See how this idea shows up as a product and a company — then come back to the lesson. Skills transfer across vendors.
Related lessons
Check your understanding
Page assessment
Answer from memory. Completion is saved from this evidence, not from opening the next page.
All responses are required.