PROJECT 04 · AdvancedPROEarly draft

Research Agent

You need a researched answer to an open question. Your mission: an agent that plans its own searches, reads what it finds, and writes a brief with checkable citations — under a budget and bounds. Not a script looping over Google — a system that makes decisions, knows when to stop, and admits when it doesn't know.

Advanced18–25h< $8Any language · an LLM API · a web-search API — the loop is hand-written; frameworks come later, if ever
Start building

What you'll build

A full agentic loop written by hand: planning, search & read tools, a complete ReAct trace, iteration/budget bounds with a give-up exit, and a synthesized brief with verified citations — with reliability and cost engineering.

Why it matters

The pre-capstone summit: the full agentic loop, the single most-asked-for skill in AI-engineering interviews. People who build it with a framework without understanding the loop itself fail the first 'so what do you do when it won't stop?' question. You'll have written it by hand — so you'll know.

Skills you'll gain

Agent loop design · L6ReAct pattern & tracesIteration caps & budget guardrailsTool-error handlingSynthesis & verified citationEvaluating agentic systemsEscalation to humans

Prerequisites

PRJ-3 evaluated + gate M7 + a web-search key.

Requirements

  • RQ-1: the agent stops at a declared iteration/budget cap — always, not usually.
  • RQ-2: every claim in the brief has a checkable source — a real URL that actually contains the cited content.
  • RQ-3: cost per run is measured and stays under the cap.
  • RQ-4: every run has a complete ReAct trace — each thought, action, and observation logged and reviewable.
  • RQ-5: a give-up exit: if the question can't be answered within bounds, the agent says so explicitly instead of fabricating or spinning.
  • RQ-6: the core loop is hand-written — no agent framework inside it.

Architecture

Product-level: question → planner → the loop (thought → action → observation) → search & read tools → synthesizer → cited brief — all inside a frame of iteration meter, cost meter, and trace log. The explanation teaches why the loop is an engineered object with bounds and stop conditions, not which framework to use.

Build — 6 stages

1The loop, by hand
2Eyes and hands
3Thinking out loud
4The brakes
5The brief, with receipts
6Evaluate & ship-ready
THE BAR — VISIBLE FROM THE START
QualityA 10-question suite: fraction of claims passing source verification ≥ the declared threshold, and the impossible question exits with an explicit give-up, not fabrication.
RobustnessTool failures (404, timeout) are handled inside the loop, the formerly-spinning question resolves in under half the cap, and every run has a complete trace.
CostMean and worst-case $/run under the declared cap, with the budget check firing before the call.

Failures you'll fix yourself

The loop that won't stopOn certain questions, the agent keeps searching with nearly the same query — turn after turn — getting no closer to an answer, until the cap kills it (if there is one).
Fabricated sources in the briefThe brief looks great: confident claims, tidy citations, plausible URLs. Open three of the links: one 404s, one is a real page that doesn't contain the claim, one checks out.
The $40 runA single run on a broad question ('compare every agent framework') cost multiples of the whole project budget. No crash, no error — just a bill.