A support engineer pasted the system prompt into Slack to ask why the bot had started agreeing with everything. Three people replied with different versions. None matched what was running in production. The string in main had been overwritten in a hotfix branch that never merged back.
That afternoon cost four hours. The fix was one sentence. Getting that sentence live took a pull request, a staging deploy, and a change window.
Hardcoded system prompts feel fine until they are not fine. Then they are expensive in a very predictable way.
What counts as hardcoding
Hardcoding is not only const SYSTEM_PROMPT = "You are..." at the top of a file. These count too:
