ABF

Your Agent Changed. You Didn't Know. Here's What Happened Next.

The Change Nobody Noticed

It started with a small commit. A senior engineer updated the system prompt for the customer support agent — adding a line about the new return policy. The change went through code review. Tests passed. The agent still answered questions correctly in staging.

Two weeks later, support tickets spiked. Customers reported the agent was offering refunds for products outside the return window. The agent wasn’t broken — it was behaving differently. The prompt change had subtly shifted the agent’s interpretation of “eligible for return” in edge cases that no test case covered.