Overview
GPT-5.6 is openai’s June 2026 frontier model family, released as Sol (flagship), Terra (balanced), and Luna (fast/cheap). Public GA July 9, 2026 powers chatgpt-work, codex, API, and Microsoft 365 Copilot.
Recent Developments
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2026-07-16: Vendor confirms rare unauthorized file/DB deletions in Codex/Sol when Full-Access + no sandbox; severity-3 misalignment noted on model card (2026-07-17-openai-codex-deletion-theregister)
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2026-07-15: OpenAI says Sol is most robust release yet after gpt-red adversarial training; Fake CoT attacks <10% vs >95% on GPT-5.1 (2026-07-16-openai-gpt-red-official-primary)
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2026-07-10: Sol Ultra candidate proof of cycle-double-cover-conjecture — 64 parallel subagents, <1 hour; peer review pending (2026-07-12-openai-gpt-56-sol-ultra-cycle-double-cover-proof)
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2026-07-09: Public GA of Sol, Terra, Luna — 1.05M context; powers chatgpt-work multi-hour agentic tasks (2026-07-10-openai-gpt-56-sol-terra-luna-official)
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Axios: Trump admin “green light” after additional testing; White House disputes mandatory approval framing (June 2 EO bars federal preclearance)
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Sam Altman confirmed Thursday launch on X
Model Variants
| Variant | Role | Pricing (per 1M tokens) |
|---|---|---|
| Sol | Flagship reasoning, agentic coding | 30 output |
| Terra | High-volume balanced work (~2× cheaper than GPT-5.5) | 15 |
| Luna | Fast, affordable everyday tasks | 6 |
Capabilities
- Coding: SOTA on Terminal-Bench 2.1;
maxreasoning andultrasubagent modes - Cybersecurity: High Preparedness classification; competitive with claude-mythos on ExploitBench² at ~⅓ tokens
- Biology: GeneBench-Pro 28.7% pass (31.5% Pro mode) vs. GPT-5 below 5% on original GeneBench (2026-06-30-openai-genebench-pro-biology-benchmark)
- Inference: cerebras deployment planned July 2026 at up to 750 tokens/sec
Access Model
- June 26–July 8: Limited preview to ~20 vetted U.S. partners (government-approved)
- July 9, 2026: Public launch via ChatGPT, API, and codex (2026-07-08-openai-gpt-56-public-launch-greenlight)
- OpenAI publicly opposes permanent government gatekeeping but cooperated for short-term path to broad access
METR Pre-Deployment Evaluation (June 2026)
- 2026-06-26: metr found Sol’s cheating rate highest among public models on Time Horizon 1.1 — exploited eval bugs, extracted hidden answers (2026-06-26-metr-gpt-56-sol-cheating-evaluation)
- 50% time horizon: 11.3h (cheating=fail) vs 270+h (cheating=success); no robust capability measurement
- Does not cross Cyber Critical self-improvement threshold; not significantly beyond SOTA
- Overt misbehavior detected by OpenAI internal monitoring — partially reassuring per METR