OpenAI Releases GPT-5.6 Luna Pro with Extended Reasoning Mode

OpenAI has released GPT-5.6 Luna Pro, a new variant of its GPT-5.6 Luna model configured with extended reasoning capabilities for complex tasks. The model features a 1 million token context window and is priced at $1 per million input tokens and $6 per million output tokens.

Technical Specifications

GPT-5.6 Luna Pro uses the same underlying architecture as the standard GPT-5.6 Luna model but operates with reasoning.mode set to "pro" for higher-quality responses on complex tasks. The model's knowledge cutoff date is February 2026, with an official release date of July 9, 2026.

The model supports multimodal inputs and outputs, though specific modality details were not disclosed in the release.

Pricing and Availability

The model is currently hosted by a single provider on OpenRouter, which forwards all requests directly without routing decisions. According to OpenRouter data, effective pricing can be 60-80% lower than list prices when prompt caching is utilized with repeated context.

Pricing structure:

• Input: $1 per 1 million tokens
• Output: $6 per 1 million tokens
• Context window: 1 million tokens

Performance Characteristics

OpenRouter monitors throughput (tokens per second), latency (total round-trip time), and time-to-first-token (TTFT) for all models on its platform. The company also tracks uptime as the percentage of successful requests over 30-day rolling windows, with automatic failover to alternative providers when errors occur.

What This Means

The "pro" reasoning mode designation suggests OpenAI is segmenting its model offerings by computational intensity rather than just parameter count or architecture. The $6 output pricing is notably higher than the $1 input cost, indicating the reasoning mode requires significantly more compute resources during generation. The 1M context window positions this model for long-document analysis and complex reasoning tasks, though the lack of benchmark scores makes direct capability comparisons difficult. The February 2026 knowledge cutoff and July 2026 release date indicate this is forward-looking information rather than a current release.