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📜 WAYPOINT LESSON

Checkpoint — ABI Reasoning

⭐ beginner⏳ 8 min read📍 Lesson 192 of 204

Grade the ABI contract itself: implement a layout-probe that proves which changes are binary-breaking versus source-compatible.

What you must be able to do

Decide, from code alone, whether a change breaks the ABI. The graded challenge freezes a struct, then asks your code to prove the layout facts a maintainer must know before touching it.