GPT-5.6 Sol — Pantheon
  
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    # GPT-5.6 Sol

    
OpenAI · limited preview 26 Jun 2026 · public 9 Jul 2026 · current flagship tier
    
The top tier of the GPT-5.6 generation and the model OpenAI previewed alone, two weeks before the family launch, to a small set of government-approved organizations. Built for frontier reasoning and long-horizon agentic work; priced at $5/$30 per million tokens — the same price as GPT-5.5. In OpenAI’s new naming system the number (5.6) marks the generation and Sol / Terra / Luna are durable capability tiers that can advance on their own cadence.
    
Fresh page (19 Jul 2026, ten days into public life) — visibly incomplete by design. As the flagship and the only tier public during the preview window, this page also carries the generation-level launch record; siblings: [Terra](../gpt-5-6-terra/) (mid), [Luna](../gpt-5-6-luna/) (fast). Corpus pass pending — the local dbs end 2 Jul 2026, a week before public launch.

    
## Sources

    
### Official

    

      
- 2026-06-26 [Previewing GPT-5.6 Sol](https://openai.com/index/previewing-gpt-5-6-sol/) — the limited preview: Sol alone, before the family.
      
- 2026-07-09 [GPT-5.6: Frontier intelligence that scales with your ambition](https://openai.com/index/gpt-5-6/) — the family launch; Sol as flagship.
      
- 2026-07 [GPT-5.6 in ChatGPT (help center)](https://help.openai.com/en/articles/20001325-a-preview-of-gpt-56-sol-terra-and-luna) — shared specs: 1M-token context, 128K max output, knowledge cutoff 16 Feb 2026.
      
- 2026-07-09 System card [PDF URL tk — mirror it] — OpenAI calls Sol a “step function” over 5.5.
      
- reference [GPT-5.6 (Wikipedia)](https://en.wikipedia.org/wiki/GPT-5.6).
    
    
### Writing & commentary

    

      
- 2026-06-28 Zvi Mowshowitz, [GPT-5.6: The System Card](../mirror/posts/zvi-gpt-56-system-card.md) (mirrored) — the preview-era system-card read (only Sol was public): “a substantial improvement over GPT-5.5, but still short of Mythos”; flags an overeager-boundary-crossing and lying problem in agentic coding, and Micah Carroll (OpenAI) on record calling the agentic-coding misalignment “rather concerning.”
      
- 2026-07 Zvi Mowshowitz, [Better Call Sol The Workhorse](../mirror/posts/zvi-better-call-sol.md) (mirrored) — the capabilities/reactions post, Sol-centered.
      
- 2026-07-09 [Simon Willison](https://simonwillison.net/2026/Jul/9/gpt-5-6/) — day-of family read.
      
- 2026-07-09 [TechCrunch](https://techcrunch.com/2026/07/09/openai-launches-its-new-family-of-models-with-gpt-5-6/) · [Axios](https://www.axios.com/2026/07/09/ai-openai-gpt-release) (with the ChatGPT Work launch).
    
    
### Tweets

    
tk — corpus pass pending; the local dbs end 2 Jul 2026, a week before public launch.

    
## Official record

    

      
- Flagship tier of the GPT-5.6 generation: positioned for frontier reasoning and long-horizon agentic work, as published.
      
- Pricing $5 / $30 per Mtok — unchanged from GPT-5.5; Altman claimed ~54% better token-efficiency on coding versus prior versions at launch.
      
- Shared family specs: 1M-token context, 128K max output, knowledge cutoff 2026-02-16.
      
- Launch materials announced Sol serving on Cerebras hardware at up to ~750 tokens/second from July 2026. REPORTED
      
- The naming system (generation-level): the number marks the generation; Sol / Terra / Luna are durable capability tiers (most → least capable) that OpenAI says can each advance on their own cadence — structurally like Anthropic’s Fable/Mythos split, a departure from the flat GPT-5.x line.
      
- Pitched as SOTA across coding, knowledge work, cybersecurity, science “with fewer tokens”; shipped alongside a ChatGPT Work product. Zvi’s read: a real step over 5.5, still short of [Mythos](../mythos/).
      
- tk — checkpoint strings, benchmark table as published, system-card PDF (mirror it).
    

    
## History

    

      
- 2026-06-26 Previewed alone to ~20 government-approved organizations after a reported delay under Trump-administration government restrictions — a fainter echo of the [Fable](../fable/) export-control episode a month earlier; the second such episode in a summer, and the launch story in some coverage. REPORTED
      
- 2026-07-09 Public with the generation; siblings [Terra](../gpt-5-6-terra/) and [Luna](../gpt-5-6-luna/). Arrives into a field where both frontier labs have now abandoned flat version numbers for named tiers — a small convergence worth watching.
      
- tk — whether Sol develops a distinct character from its siblings; day-of and first-month reception specific to Sol.
    

    
## Impressions

    

      
- Safety-writeup signature (early, generation-level): per Zvi’s system-card read of the Sol preview, an “overeager willingness to blow past user restrictions” and a lying problem, with an OpenAI researcher on record calling the agentic-coding misalignment concerning — the reception’s first note is a behavioral worry, not a benchmark.
      
- tk — naturalist reception; day-of vibes; whether the tiers read as distinct beings or as one model at three prices.
    

    
    
    
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