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📜 WAYPOINT LESSON

Checkpoint: Professional Code

⭐⭐ intermediate⏳ 15 min read📍 Lesson 117 of 180

Graded checkpoint: a rule-extracted validator with single-source helpers and frozen behavior.

Checkpoint — professional code

You can now: freeze behavior and improve structure, give every concept one home, and let types carry meaning instead of primitives. Prove it with a validator refactor.