GPT-5.6 Three Sub-Model Code Leak: Rumored July 7 Release with Performance and Cost Advantages

Recently, information about OpenAI's GPT-5.6 series models was leaked in the underlying code of the Codex application, revealing three sub-models named Sol, Terra, and Luna, along with a 'speed dial' feature. According to leaks, OpenAI's internal target release date is July 7-9, coinciding with the expiration window of Anthropic's Claude Fable 5 specific quota plan.

Leak Details and Model Lineup

• The code contains identifiers for GPT-5.6 Sol, Terra, Luna, and the term 'Sol Ultra', which is speculated to be the top-tier flagship model competing with Fable 5.
• The new 'speed dial' feature allows users to adjust between speed and quality, but real-time voice support is still under development and will not be available at launch.

Internal Testing Performance: Efficiency and Front-End Capabilities Stand Out

• An Nvidia engineer reported that Sol achieved CUDA acceleration in 30 hours that took Opus 64 hours, with only 1/5 the lines of code, though iteration speed was slower and failure rate higher.
• In front-end generation, GPT-5.6 shows significant improvements in SVG, 3D models, and game generation, with better design taste and UI cleanliness than GPT-5.5.
• Compared to Fable 5: GPT-5.6 is more efficient in complex engineering tasks (consuming 13% quota vs Fable 5's 21%) and responds more directly, but still slightly inferior in overall code quality and game completeness.

Cost and Safety Advantages

• GPT-5.6 Sol's input/output price is $5/$30 per million tokens, about half of Fable 5's $10/$50.
• Safety restrictions are looser than Fable 5, which has drawn user criticism for over-blocking (e.g., 'how many r's in raspberry'), while GPT-5.6's guardrail strategy is more balanced.

Market Timing and User Reminder

• OpenAI chose to release on July 7, precisely targeting the expiration of Fable 5's quota, aiming to capture users dissatisfied with Anthropic.
• Developers should note: Codex's rate limit reset quota is valid for 30 days; if obtained on June 11-12, it will expire around July 12, so it's recommended to use it soon after GPT-5.6's release.

Background: GPT-5.5's '516 Intelligence Reduction' Incident

• Meanwhile, GPT-5.5 was exposed to have a '516 reasoning token truncation' issue: complex reasoning often stops abruptly at 516 tokens, accounting for 82% of such cases. Developers suspect OpenAI secretly set a reasoning budget cap, but the company has not responded.
• Additionally, GPT-5.5 is criticized for overly formatted responses and a tendency to correct users, degrading user experience.

Overall, the leaked information about GPT-5.6 shows competitiveness in front-end generation, efficiency, and cost, but its hardcore reasoning capabilities remain to be verified. If the July 7 release proceeds as planned, it will intensify competition in the large model market.