BitSketch Academy

The Agent Loop, From Scratch

Build the loop every AI agent runs on, in plain Python, and learn exactly where it breaks.

Text courseBeginnerFree

Frameworks hide the loop. This short course takes it apart: one model call, one tool, one stopping rule at a time. By the end you can read any agent framework's source and know what it is doing, and why your agent loops forever or quits too early.

What you'll learn

  • Write a working agent loop in about 30 lines
  • Expose tools so the model can act, and handle their errors
  • Stop the loop on purpose: budgets, step limits and done-checks
  • Decide what state to keep between steps and between runs
  • Debug a run from its trace, and replay it without paying for model calls
  • Build a codebase Q&A agent end to end, and find the same loop inside any framework

Course content

Chapter 1How the loop works2 lessons · 13 min
  1. 1The loop in 30 linesAn agent is a while-loop around a model call. Here is the whole thing, with nothing hidden.6 min
  2. 2Tools: how the model actsThe model never runs code. It asks, you run, you report back. Get that contract right and most bugs disappear.7 min
Chapter 2Making it safe to run2 lessons · 16 min
  1. 3Stopping on purposeStep limits, cost budgets, loop detection, done-checks and human approval: the brakes every loop needs before it touches anything real.8 minFree with email
  2. 4Where the agent's state livesThe message list is short-term memory. Learn what to keep, what to trim, and what to save outside the loop.8 minFree with email
Chapter 3Build one for real3 lessons · 30 min
  1. 5Debugging from the traceThe final answer is a claim; the trace is the evidence. Log every step, spot the usual failure shapes, and replay a run for free.10 minFree with email
  2. 6Project: a codebase Q&A agentEvery lesson in one working program: three read-only tools, brakes, and a done-check that verifies every citation.12 minFree with email
  3. 7Finding the loop in any frameworkFour searches that find the loop inside any agent framework, what frameworks really add, and when you need one.8 minFree with email