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Reasoning Models Architecture & Controls — OpenAI Frontier Architecture

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Reasoning Models Architecture & Controls

🧠 OpenAI Frontier Architecture 15 min 400 BASE XP⌨ HANDS-ON LAB

OpenAI Frontier Reasoning: GPT-6 Family & Codex

OpenAI's unified GPT-6 reasoning family (GPT-6 Astra, GPT-6.1 Sol, GPT-6.1 Terra, and GPT-6 Luna) succeeds the retired o1, o3-mini, and o4-mini models (shut down October 23, 2026) and deprecated o3/o3-pro models (sunset December 11, 2026). Trained with reinforcement learning to generate internal chains of thought across a 1.05M-token context window (128K max output), these models power STEM proofs, multi-file software engineering, and autonomous coding via Codex CLI (@openai/codex) and Codex Cloud.

Calibrating Reasoning Effort

In the Responses API, calibrate thinking depth via reasoning: { effort: ... } (or reasoning_effort in Chat Completions):

Effort LevelLatencyBest For
none (Luna only)Ultra-FastSub-second classification, extraction, high-volume chat routing
lowFastStraightforward code fixes, light edits, fast decision routing
medium (default)BalancedGeneral software engineering, data analysis, standard multi-step reasoning
high / xhigh / maxThoroughComplex mathematical proofs, multi-repo refactoring, long-horizon agentic execution
const response = await openai.responses.create({
  model: "gpt-6.1-sol",
  reasoning: { effort: "high" },
  input: [
    { role: "developer", content: "You are a senior algorithmic engineer." },
    { role: "user", content: "Optimize this dynamic programming solution for memory bounds." }
  ]
});

Developer Messages & Codex Harnesses

Reasoning models replace the legacy system role with the developer role to preserve strict instruction hierarchy. For repository-scale automation, pair GPT-6 Astra or Sol with Codex CLI (npm install -g @openai/codex, configured via ~/.codex/config.toml and repo AGENTS.md files) or asynchronous Codex Cloud virtual machines.

💡 Best Practice: GPT-6 reasoning models natively combine Structured Outputs (strict: true), remote MCP servers, and parallel Function Calling inside their reasoning loops.
⌨ HANDS-ON LABDeploy Developer Messages on GPT-6.1 Sol
⭐ +200 XP

OpenAI reasoning models replace the legacy system role with developer messages for strict behavioral hierarchy. Submit a developer-scoped instruction to gpt-6.1-sol.

1POST to /v1/responses targeting gpt-6.1-sol using the developer role instead of system.
lab-sandbox — simulated environment
INFINITY LAB SANDBOX v2.6 — simulated shell
Type the command for the current objective. Helpers: "hint", "solution", "clear".
$
OBJECTIVE 1 / 1 — type "hint" if stuck
SYNAPSE VERIFICATION
QUERY 1 // 4
Which parameter controls the depth of internal reasoning tokens in the OpenAI Responses API?
temperature
reasoning.effort ('none' on Luna | 'low' | 'medium' | 'high' | 'xhigh' | 'max')
max_reasoning_tokens
thinking_depth