GitHub Copilot CLI Adds Plan Mode and GPT-5.2-Codex in Major Update

GitHub shipped a substantial update to Copilot CLI on January 21, 2026, introducing plan mode—a feature that lets developers collaborate with the AI before any code gets written. The update also brings GPT-5.2-Codex and session management tools that effectively eliminate context window limitations.

Plan mode addresses a persistent frustration with AI coding assistants: they often start implementing before fully understanding the task. Press Shift + Tab to enter plan mode, where Copilot analyzes your request, asks clarifying questions about scope, and builds a structured implementation plan. You review and approve before a single line of code appears.

The new ask_user tool powers this conversational approach, prompting for input on design decisions and confirming assumptions. Think of it as a technical spec session with an AI that actually listens.

GPT-5.2-Codex and Reasoning Controls

The latest Codex model optimized for code generation is now available via the /model command or --model gpt-5.2-codex flag. GitHub added configurable reasoning effort for GPT models with extended thinking capabilities, letting developers balance response speed against reasoning depth.

Ctrl + T toggles visibility of the model's reasoning steps during generation. The setting persists across sessions—useful for understanding how Copilot approaches complex problems or debugging unexpected outputs.

Infinite Sessions and Real-Time Steering

Auto-compaction kicks in when conversations hit 95% of the token limit, compressing history in the background without interruption. Manual compression is available via /compact, and /context shows detailed token usage breakdown.

Developers can now queue additional messages while Copilot is thinking—send follow-up instructions or steer the conversation without waiting. When rejecting a tool permission request, inline feedback helps Copilot adapt its approach rather than halting entirely.

Code Review and Memory

The /review command analyzes staged or unstaged changes directly in the terminal. Copilot also now stores conventions, patterns, and preferences it learns across sessions, making future interactions more productive.

GitHub Copilot has been activated by over one million developers and adopted by more than 20,000 organizations since launch. The CLI entered public beta in November 2023, with reports indicating roughly 30% of coding suggestions get accepted.

Update via brew upgrade copilot-cli, winget upgrade GitHub.Copilot, or npm install -g @github/copilot@latest. GitHub CLI users can run gh copilot to get started—first-time use prompts automatic installation.