The Soul of an AI Coding Assistant: The Think-Act-Observe Loop

blog@baifan.site (ByF (BaiFan)) — Thu, 07 May 2026 09:00:00 +0800

If you dig through the Claude Code source, you will discover a counterintuitive fact:

The core of the entire program is a while loop.

Not a complex state machine, not an elaborate pipeline, not distributed coordination — just a plain while loop that does three things over and over: let the model think, let the model act, feed the results back.

while (user hasn't quit) {
  thinking = callLLM(conversation history + tool definitions)
  if (thinking.wants to call a tool) {
    result = executeTool(thinking.toolCall)
    conversationHistory.push(result)
  } else {
    output(thinking.reply)
  }
}

That’s it? The entire secret of an AI coding assistant lives in this loop?

Agent Loop on ByF (BaiFan) · Daily Deep Think

The Soul of an AI Coding Assistant: The Think-Act-Observe Loop