6.1 Agent Loop Fundamentals¶

Role at Stage 6: AI Agents¶

Build the observe-think-act-observe-finish loop explicitly before using frameworks. This part is one capability inside the stage. It should leave behind an artifact, measurements, and a short explanation of failure modes.

Explanation¶

This part has 4 sub-parts because the topic needs that many learning units to feel natural. Some stages have more parts and some have fewer; the structure follows the topic, not a fixed template.

Part Diagram¶

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flowchart LR
  P["<b>6.1</b><br/>Agent Loop<br/>Fundamentals"]
  P --> S1["<b>6.1.1</b><br/>Agent State and<br/>Messages"]
  P --> S2["<b>6.1.2</b><br/>Observe Reason Act<br/>Observe"]
  P --> S3["<b>6.1.3</b><br/>Final Answer and Stop<br/>Rules"]
  P --> S4["<b>6.1.4</b><br/>Loop Budget and<br/>Cancellation"]
  P --> E["<b>Exam</b><br/>Part practice"]

Sub-Parts¶

Sub-part folder	What it explains
6.1.1 Agent State and Messages	Agent State and Messages is the working skill inside Agent Loop Fundamentals that helps you build the stage artifact, A tool-using agent with typed tools, memory, traces, task evals, prompt-injection tests, and an architecture README, while collecting enough evidence to trust the result.
6.1.2 Observe Reason Act Observe	Observe Reason Act Observe is the working skill inside Agent Loop Fundamentals that helps you build the stage artifact, A tool-using agent with typed tools, memory, traces, task evals, prompt-injection tests, and an architecture README, while collecting enough evidence to trust the result.
6.1.3 Final Answer and Stop Rules	Final Answer and Stop Rules is the working skill inside Agent Loop Fundamentals that helps you build the stage artifact, A tool-using agent with typed tools, memory, traces, task evals, prompt-injection tests, and an architecture README, while collecting enough evidence to trust the result.
6.1.4 Loop Budget and Cancellation	Loop Budget and Cancellation is the working skill inside Agent Loop Fundamentals that helps you build the stage artifact, A tool-using agent with typed tools, memory, traces, task evals, prompt-injection tests, and an architecture README, while collecting enough evidence to trust the result.

What a Person Who Masters This Part Can Do¶

Explain how Agent Loop Fundamentals supports a tool-using agent with typed tools, memory, traces, task evals, prompt-injection tests, and an architecture readme..
Build and inspect this artifact: Build a manual ReAct-style agent.
Measure progress with: Track steps, success, invalid actions, and stop reasons.
Debug at least one failure mode before moving to the next part.

Build and Measure¶

Build: Build a manual ReAct-style agent.

Measure: Track steps, success, invalid actions, and stop reasons.

Tests¶

Take one 30-question exam after studying this part. It opens in a new browser tab so the study page stays available.

Open Part Exam

Back to Stage¶

Return to Stage 6: AI Agents.