Cutting LLM costs in Spring AI starts with two choices: which model answers a request, and what defaults your ChatClient adds to every one it sends. Neither is worth changing until you can see where the tokens go. That is why this article starts with measurement. This is Part 1 of four, and it covers the first three of ten cost drivers. Driver #0 tells you where the money actually goes; #1 and #2 are the two decisions that shape every request your application sends. The remaining seven ...