Simon Willison’s Weblog

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4th January 2026

It genuinely feels to me like GPT-5.2 and Opus 4.5 in November represent an inflection point - one of those moments where the models get incrementally better in a way that tips across an invisible capability line where suddenly a whole bunch of much harder coding problems open up.

This is a note by Simon Willison, posted on 4th January 2026.

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