The Best Coding Model So Far: Sonnet 4.6 (Hands-On Review)

February 15, 2026 — After 48 hours of intense testing, the verdict is in: Claude Sonnet 4.6 is currently the best coding model on the planet. It strikes the perfect balance between the creative architectural reasoning of Opus and the raw speed of Haiku.

Test Case 1: Legacy Refactor

We threw a 500-line spaghetti code Java file (circa 2015) at it. Not only did it refactor it into clean, functional patterns, but it also correctly identified deprecated libraries and suggested modern replacements without being asked.

Test Case 2: The React Race Condition

Debugging `useEffect` race conditions is a rite of passage. Sonnet 4.6 didn't just patch the bug; it explained why the cleanup function was failing in a single sentence and provided the AbortController pattern as a fix.

IDE Integration

Inside Cursor and VS Code, the model shines. Its ability to grasp context from multiple open tabs (thanks to the 1M context beta) means it understands your entire project structure, not just the file you're editing.

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