Grok 4.6 ships with 500K context; Fable 5 parity claim holds on one index, not head-to-head

SpaceXAI released Grok 4.6 on 12 August 2026: a post-training upgrade on the same V9 base as Grok 4.5 rather than a new foundation model, with a 500,000-token context window and a new top reasoning level, xhigh. xAI's published pricing is $2 per million input tokens and $6 per million output for prompts under 200,000 tokens, doubling to $4 input and $12 output above that boundary, with cached…