[AINews] SpaceXAI launches Grok 4.5, first Opus-class model post Cursor acquisition

SpaceXAI launched Grok 4.5, an Opus-class model focused on coding and agents, trained in partnership with Cursor. The model offers near-frontier performance with faster speed and lower cost, positioning itself as a competitive alternative to GPT-5.5 ahead of OpenAI's GPT 5.6 launch.

AINews SpaceXAI launches Grok 4.5, first Opus-class model post Cursor acquisition SpaceXAI continues to move faster than any other frontier lab on earth. As GPT 5.6 is confirmed to launch tomorrow https://x.com/openai/status/2074704958419792299 , today is pretty much the last day anyone will be excited about a GPT 5.5 equivalent model launch, and that is exactly what SpaceXAI did: The new Grok 4.5 https://cursor.com/blog/grok-4-5 is a different weight class https://x.com/cursor ai/status/2074915748544217188 than the Composer series 1.5T https://x.com/ArtificialAnlys/status/2074956932289282087 and despite the solid evals still performs very comparably to the current workhorse Opus and GPTs, although per OpenAI’s evals team even the mighty SWE-Bench Pro is now saturated/terminally flawed https://news.ycombinator.com/item?id=48837396 - leaving presumably a small list of successors including FrontierCode https://www.latent.space/p/ainews-frontiercode-benchmarking . As for training and data disclosures, this is all the information we have. AI News for 7/07/2026-7/08/2026. We checked 12 subreddits, 544 Twitters and no further Discords. AINews’ website lets you search all past issues. As a reminder, AINews is now a section of Latent Space . You can opt in/out of email frequencies AI Twitter Recap Top Story: Grok 4.5 release What happened xAI/“SpaceXAI” publicly launched Grok 4.5 as a new coding-and-agents-focused frontier model, positioned on capability-per-dollar rather than absolute benchmark supremacy. Elon Musk first said Grok 4.5 would be made public “tomorrow” based on strong beta feedback, calling it “Opus-class,” but faster, more token-efficient, and lower cost @elonmusk https://x.com/elonmusk/status/2074740539874775163 .Musk later framed Grok 4.5 internally as “roughly comparable to Opus 4.7, but much faster,” emphasizing usefulness to Tesla and SpaceX engineers over benchmark chasing @elonmusk https://x.com/elonmusk/status/2074911038286295049 .The official launch came from xAI’s account, describing Grok 4.5 as “our first model trained specifically for coding and agents,” trained with Cursor, and offering “frontier intelligence at leading speeds and cost efficiency” @SpaceXAI https://x.com/SpaceXAI/status/2074915721684086811 .Cursor said it partnered with xAI to train Grok 4.5, called it “our most powerful model yet,” and stressed that it was “the first we’ve built for more than software engineering” @cursor ai https://x.com/cursor ai/status/2074915744999969059 .Cursor also announced in-product availability with “double usage for the first week” @cursor ai https://x.com/cursor ai/status/2074915747302690991 .Cursor clarified that “Grok 4.5 and Composer are two different model weight classes,” and that Composer 2.5 would remain available with future models in that smaller class @cursor ai https://x.com/cursor ai/status/2074915748544217188 .Early ecosystem support appeared immediately: Grok 4.5 became available in Grok Build/API/Cursor @milichab https://x.com/milichab/status/2074916029848027636 , day-0 support was announced for Hermes Agent @Teknium https://x.com/Teknium/status/2074823590365860254 , and later live availability in Hermes Agent/Portal/OpenRouter/Grok subscriptions was confirmed @Teknium https://x.com/Teknium/status/2074943072761471314 .Musk said the context window would likely move from 500k back to 1M “by next week” @elonmusk https://x.com/elonmusk/status/2074963933199282491 . Official claims and product details Positioning Officially, xAI’s message was not “best overall model,” but near-Opus quality with materially better economics and speed: “Opus-class model, but faster, more token-efficient and lower cost” @elonmusk https://x.com/elonmusk/status/2074740539874775163 “First model trained specifically for coding and agents” @SpaceXAI https://x.com/SpaceXAI/status/2074915721684086811 “Frontier intelligence at leading speeds and cost efficiency” @SpaceXAI https://x.com/SpaceXAI/status/2074915721684086811 “Most powerful model yet” and “first we’ve built for more than software engineering” @cursor ai https://x.com/cursor ai/status/2074915744999969059 This framing matters: xAI is explicitly targeting the coding-agent workflow market that has recently been dominated by Anthropic/OpenAI/Cursor-style tool-using systems, not just general chat. Pricing and context The concrete numbers that surfaced: Official pricing: $2 / 1M input tokens, $6 / 1M output tokens @scaling01 https://x.com/scaling01/status/2074914032880947601 Artificial Analysis repeated the same price point and added: cache hits discounted by 75% to $0.5 / 1M tokens long inputs over 200k tokens cost double 500k context window , down from Grok 4.3’s 1M vision input retained configurable reasoning retained @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 Musk later said the context window would probably upgrade back to 1M soon @elonmusk https://x.com/elonmusk/status/2074963933199282491 . Relative pricing comparisons cited by users: Grok 4.5: $2 in / $6 out GPT-5.6: $5 in / $30 out Opus 4.8: $5 in / $25 out @kimmonismus https://x.com/kimmonismus/status/2074940669718638780 Model size One important spec surfaced via third-party reporting of Musk’s disclosure: Grok 4.5 is 3x larger than Grok 4.3 at 1.5T parameters @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 That is a notable jump, and likely central to why multiple observers interpreted 4.5 as xAI’s first entry into the true flagship coding-agent tier rather than an iterative refresh. Benchmarks and independent evaluations Artificial Analysis Artificial Analysis provided the most substantive external evaluation in the tweet set. Key results: 4 on Artificial Analysis Intelligence Index , score 54 , behind only Fable 5, GPT-5.5, and Opus 4.8 @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 +16 points vs Grok 4.3 on the same index @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 GDPval-AA v2 Elo 1543 , also ranking 4 , behind Anthropic’s latest Claude releases @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074942097158021371 Top score on τ³-Banking: 33% , above 31% for GPT-5.5 xhigh @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 Artificial Analysis Coding Agent Index score 76 in Grok Build, “on par with GPT-5.5 in Codex” and below Fable 5 in Claude Code @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 Cost per Intelligence Index task: $0.31 @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 Cost per GDPval task: $0.49 @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074942097158021371 Cost per Coding Agent Index task: $2.59 @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 Average output tokens per Intelligence Index task: ~14k , over 60% lower than Opus 4.8 @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 Average total tokens per Coding Agent Index task: 1.9M , versus 7.2M for Fable 5 in Claude Code and 6.2M for GPT-5.5 in Codex @ArtificialAnlys https://x.com/ArtificialAnlys/status/2074956932289282087 Artificial Analysis’ interpretation was clear: Grok 4.5 is near-frontier on capability, but unusually strong on efficiency, making it sit on the Pareto frontier for cost/performance. Musk explicitly amplified the Artificial Analysis assessment @elonmusk https://x.com/elonmusk/status/2074948489792860456 . Keep reading with a 7-day free trial Subscribe to Latent.Space to keep reading this post and get 7 days of free access to the full post archives.