The Best Terminal Setup for Codex CLI & Gemini CLI on Mac (2026)

Most terminal-setup guides assume Claude Code. But plenty of people live in Codex CLI and Gemini CLI all day, and those tools have their own quirks worth tuning for. The terminal is the entire interface for an AI coding agent — it's where prompts go in and structured, colored, sometimes very long output comes back — so a few settings make the difference between a workflow that feels sharp and one that feels like fighting the window. Here's how to set up a Mac terminal that serves Codex CLI and Gemini CLI well.

Why the terminal matters more for AI CLIs

A traditional shell session is short bursts: run a command, read a line or two, move on. AI CLIs invert that. The agent streams long, structured responses — file trees, diffs, multi-step plans, tool calls — often using box-drawing characters, icons, and color to organize it all. If your terminal renders any of that poorly, you feel it constantly. Three things matter most: glyph coverage (so nothing renders as tofu), color fidelity (so diffs and status colors are accurate), and scrollback (so a long agent turn doesn't scroll its own start off the top of the world).

Fonts: use a Nerd Font

Both Codex CLI and Gemini CLI lean on box-drawing characters and icon glyphs for structured output. Use a Nerd Font so those render correctly — JetBrains Mono Nerd Font is a safe, free default. Our full nerd font guide ranks the rest. Set it around 14pt; agent output is dense, and a slightly larger glyph reduces fatigue over a long session.

Colors: pick a high-contrast, true-color palette

Make sure your terminal advertises TERM=xterm-256color (or a true-color equivalent) so 24-bit color works — AI CLIs use it for syntax-highlighted diffs and colored status. Then pick a palette with enough contrast that greens, reds, and yellows stay distinct against the background. Dracula, Nord, and Gruvbox all handle colored agent output well; see our themes guide for the trade-offs.

The settings that actually matter

• Generous scrollback. Set it to 10,000 lines or more. A single Gemini CLI turn can be long, and you'll want to scroll back through the whole thing.
• True color on. Confirm 24-bit color; without it, diffs look muddy.
• A quiet prompt. Starship keeps your prompt short so the agent's output — not your shell chrome — is the thing on screen.
• Comfortable padding. 16px of window padding keeps dense output off the chrome.

Codex CLI specifics

Codex CLI is happiest with a wide window — its diffs and plans use horizontal space, and a cramped column forces awkward wrapping. Give it room, keep the font readable, and make sure your color scheme keeps added/removed diff lines clearly distinct. If you run it in a multi-pane setup, confirm each pane still reports true color.

Gemini CLI specifics

Gemini CLI leans on structured, sometimes icon-heavy output, so the Nerd Font point is non-negotiable here — plain fonts turn its nicer formatting into boxes. It also benefits from the generous scrollback: its longer turns are the ones most likely to scroll their own context away.

The window itself

Once the fundamentals are set, the terminal window is the last variable. If you want more than a color scheme — a look that's unmistakably your workspace — Terminal Candy is a native macOS terminal (full disclosure, ours) that skins the whole window while running a real PTY inside, so Codex CLI and Gemini CLI behave exactly as they would anywhere else. True color, deep scrollback, multi-session — all intact; the difference is purely what it looks like. Browse the skin gallery if you want to see the range.

Dial in font, color, and scrollback first — that's 90% of a great AI-CLI terminal. The rest is personality.