Which has fewer bugs, Claude Opus 4.8 or GPT-5.6 Luna?

Claude Opus 4.8 had 31% fewer counted bugs per line than GPT-5.6 Luna (0.88 vs 1.28). Claude Opus 4.8 ranks #2 of 7 and GPT-5.6 Luna #5.

Which is used more, Claude Opus 4.8 or GPT-5.6 Luna?

Claude Opus 4.8, with 1.9% of the AI-written code reviewed by cubic in the week of Sep 14, 2026, against 1.7% for GPT-5.6 Luna.

Updated Sep 26, 2026

Claude Opus 4.8 had 31% fewer counted bugs per line than GPT-5.6 Luna (0.88 vs 1.28).

Claude Opus 4.8 and GPT-5.6 Luna compared on relative bug rate, by coding agent, bug type, and language, and on price and usage.
Bug rate
	Claude Opus 4.8	GPT-5.6 Luna
Relative bug rate	0.88	1.28
Rank	#2 of 7	#5 of 7
Details
Share of AI-written code, week of Sep 14	1.9%	1.7%

1.00 = average · lower is better

Which has fewer bugs, Claude Opus 4.8 or GPT-5.6 Luna?: Claude Opus 4.8 had 31% fewer counted bugs per line than GPT-5.6 Luna (0.88 vs 1.28). Claude Opus 4.8 ranks #2 of 7 and GPT-5.6 Luna #5.
Which is used more, Claude Opus 4.8 or GPT-5.6 Luna?: Claude Opus 4.8, with 1.9% of the AI-written code reviewed by cubic in the week of Sep 14, 2026, against 1.7% for GPT-5.6 Luna.