SWE-bench February Analysis: The 80% Ceiling and What It Means

simonwillison.net — Four models now above 80% SWE-bench (Opus 4.6 at 80.8%, Gemini 3.1 Pro at 80.6%, GPT-5.3-Codex at 80.0%, Kimi K2.5 at 76.8%). Willison's analysis: we're approaching the ceiling where SWE-bench stops being a meaningful differentiator. The gap between models is now smaller than the gap between scaffolding approaches. This is the quantitative backing for the "scaffolding > model" thesis.