How to Control Reasoning Effort in Codex CLI for Faster or Smarter Responses

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OpenAI's Codex CLI offers a configurable 'model_reasoning_effort' setting that lets developers control how deeply the model reasons before responding, with five levels ranging from 'minimal' to 'xhigh'. The setting can be applied permanently via the ~/.codex/config.toml file, overridden for a single run using the -c flag, or adjusted mid-session with the /model command. Higher effort levels suit complex tasks like multi-file design changes or hard algorithms, while lower levels are better for simple fixes and formatting tasks. Developers can also bundle effort settings into named profiles for repeated workflows, such as code reviews requiring maximum reasoning. Additional keys like 'plan_mode_reasoning_effort' and 'agents.default_subagent_reasoning_effort' allow fine-grained control over planning mode and subagent behavior separately.

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How to Verify Which Python Binary Your Code Actually Runs

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ProgrammingDEV Community ·

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ProgrammingDEV Community ·

Opik: Open-Source LLM Observability Tool Lets Teams Self-Host Agent Tracing

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ProgrammingDEV Community ·

Developer flags self-asserted test steps and untestable surfaces in E2E run

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