Stop a failing agent loop

WHAT YOU WILL BUILD

A finite execution trace that cannot retry forever.

The useful part of an agent loop is the feedback between a proposed action and an observed result. The controller also needs explicit terminal states. A sequence of unsuccessful calls should consume a finite budget rather than becoming an unbounded conversation.

FOLLOW ALONG

Work through the example.

1. 01

   Read the failure sequence

   The supplied sequence has three temporary failures followed by a success. With a maximum of three attempts, that fourth event must never be reached.

2. 02

   Run the bounded controller

   The output is Attempts: 3 and Final state: exhausted. Follow the counter increment and the check at the top of the loop to understand the boundary.

3. 03

   Exercise early termination

   Replace the second outcome with success and predict two attempts with complete status. Then use permanent-error and expect two attempts with failed status. Update the assertions for each fixture.

4. 04

   Plan the production limits

   Alongside attempt limits, set a wall-clock deadline, per-call timeout, and spending limit for actual integrations. Decide which terminal states require human help and record the completed work before stopping.

THE COMPLETE LAB

Run it locally.

Run this command from the folder containing your downloaded file:

node agent-stop-conditions.mjs

// SaveMyToken local lab. Run with Node.js 22 or newer.
import assert from "node:assert/strict";

// A deterministic controller, not an LLM agent or a live service.
const outcomes = ["transient-error", "transient-error", "transient-error", "success"];
const maxAttempts = 3;
let attempts = 0, status = "exhausted";
for (const outcome of outcomes) {
  if (attempts >= maxAttempts) break;
  attempts++;
  if (outcome === "success") { status = "complete"; break; }
  if (outcome === "permanent-error") { status = "failed"; break; }
}
console.log("Attempts:", attempts);
console.log("Final state:", status);
assert.equal(attempts, 3);
assert.equal(status, "exhausted");

Expected output for the unchanged example

Attempts: 3
Final state: exhausted

The assertions also check the baseline behavior. After changing an input, predict the result and update the relevant assertion.

EXPLAIN WHAT YOU LEARNED

Interview practice

Try answering aloud before opening the reference answer. These are original learning questions, not a record of any employer's interviews.