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GPT-6 Luna is the fast, low-cost tier of OpenAI's GPT-6 series (1.05M-token context, text, image, and file input, $0.10/$0.50 per million input/output tokens), released September 22, 2026 below GPT-6 Sol and the flagship GPT-6 Astra. It is built for high-volume tasks with a clear goal, such as summarization, extraction, classification, quick questions, and lightweight agentic steps.

GLM-5.3-FlashX is Z.ai's speed-optimized variant of GLM-5.3-Flash, a natively multimodal MoE model (around 320B total / 18B active parameters, MIT-licensed, 1M-token context) built on the same hybrid sparse-and-linear attention architecture. It generates at up to 200 tokens/sec for latency-sensitive coding and long-horizon agent tasks that still need the full 1M-token context, at a premium over the standard GLM-5.3-Flash endpoint.