GPT-5.4 Thinking System Card Released: OpenAI Publishes Technical Specification for New Reasoning Architecture

Core Contents of the GPT-5.4 Thinking System Card

The GPT-5.4 Thinking System Card, published by OpenAI, is a transparency-focused technical specification intended for developers and researchers, emphasizing system-level behavioral modeling of GPT-5.4 on complex reasoning tasks—not just benchmark scores.

• The document formally defines a dual-phase execution paradigm: ‘Thinking Mode’ (activating Tree-of-Thought (ToT)-based deep search with dynamic backtracking) and ‘Response Mode’ (generating final output from verified thought paths);
• Introduces the ‘Self-Verification Token (SVT)’ mechanism—learnable verification tokens inserted at intermediate reasoning steps, enabling confidence scoring and resampling of sub-conclusions; reduces multi-step arithmetic error rate by 37.2% on GSM8K vs. GPT-4 Turbo;
• Exposes fine-grained control interfaces: configurable via thinking_depth=3–12 and verification_threshold=0.65–0.92;
• All design choices are grounded in the theoretical framework presented in arXiv:2408.12345 (Scalable Self-Reflective Reasoning in LLMs) and strictly aligned with OpenAI’s internal training pipeline (v5.4.1-train).