A small test of the learning cost Dru flagged: 52 developers tried an unfamiliar Python library. With AI chat, all 26 finished the second task; without it, 22 of 26 did. But the AI group scored 4.15 points lower on a 27-point immediate, unaided comprehension quiz. Finishing and learning were different outcomes here—not a measure of long-term skill or full coding-agent use.