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Codex Themes Download: Desktop Imports and CLI .tmTheme Files

For Codex desktop, copy a DexThemes `codex-theme-v1:` string and approve it in Appearance. Codex CLI uses custom `.tmTheme` files instead, but DexThemes does not currently distribute those CLI files.

Written by Daeshawn Ballard Updated 1,272 words
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To download Codex themes without using the wrong artifact, first choose the surface you want to change. For the graphical Codex workspace in the desktop app, DexThemes gives you plain text to copy and import; it is not an executable download or an automatic installer. For terminal syntax highlighting in Codex CLI, the relevant artifact is a .tmTheme file selected through the CLI’s /theme picker. DexThemes does not currently distribute those CLI files.

The two options are separate. A desktop codex-theme-v1: string cannot become a CLI theme just by saving it with a .tmTheme extension, and a .tmTheme file does not belong in the desktop Appearance importer.

Choose the right Codex theme artifact

You want to change the desktop Codex workspace

Choose a DexThemes dark or light variant and copy its complete codex-theme-v1: string. Then use Settings → Appearance → Import theme in the installed desktop app, review the result, and approve it.

The current DexThemes desktop handoff creates a text import string, copies it to the clipboard, and can open general Codex Settings. It does not silently change your Appearance settings. OpenAI’s Settings documentation describes Appearance controls for the base theme, accent, background, foreground, and UI and code fonts; follow the controls shown by your installed app if their names or layout differ.

Use this path when you want the app workspace to reflect a palette: its main surfaces, foreground, accent, semantic colors, optional font names, and code-theme family. See How to install a Codex theme for the full import sequence.

You want to change Codex CLI syntax highlighting

Use the CLI’s /theme picker. OpenAI’s CLI customization documentation says the picker previews a selection and saves it to tui.theme in $CODEX_HOME/config.toml. If the built-in choices do not give you the syntax palette you need, place a custom .tmTheme file in $CODEX_HOME/themes and select it in that picker.

A .tmTheme file is appropriate when you need a custom terminal syntax-highlighting palette. It is a separate CLI artifact—not a DexThemes desktop import string. DexThemes does not currently provide these files, so obtain or author one elsewhere, inspect it, and store it as a CLI theme file.

You use both the desktop app and CLI

Keep two artifacts: one codex-theme-v1: string for each desktop variant, and one .tmTheme file only if you use a custom CLI theme. They can share a visual direction, but neither artifact installs or updates the other. Codex app themes vs CLI themes explains why a direct conversion is incomplete.

A DexThemes desktop theme is copied text, not a program download

Calling a desktop theme a “download” can make the handoff sound more automatic than it is. The actual artifact is a visible text value that begins with codex-theme-v1: and continues with one JSON object. It carries appearance data, including a code-theme family ID, one dark or light variant, colors, contrast, an opaque-windows preference, and optional font names.

It is not an app, browser extension, shell command, font installer, or configuration-directory archive. Copying it does not prove that Codex accepted it, and opening Settings does not prove that the theme was applied. Codex owns the final import, review, and persistence step.

For a desktop theme, the safe, portable sequence is short:

  1. Open the canonical DexThemes theme page and select the dark or light variant you want.
  2. Copy the entire string, including the codex-theme-v1: prefix.
  3. Open Codex Settings yourself, or use the general Settings handoff if you want it.
  4. Choose Appearance → Import theme, paste the unchanged string, review it, and approve it.
  5. Check ordinary prose, code, diffs, selections, and fonts in the installed app.

If you only need a theme on another computer, save the copied value as UTF-8 plain text and import it there. Keep dark and light strings separate. The move-a-theme guide covers the destination checks and font caveats.

When to download or create a .tmTheme file

Choose a .tmTheme file only when the goal is the Codex CLI terminal interface. It is useful when the /theme picker’s supplied choices are close but do not provide the token-level syntax colors you need.

Do not use a .tmTheme file merely because you prefer the name or preview of a desktop DexThemes palette. A desktop import carries broad workspace appearance data and a registered code-theme family, while the CLI loads its own .tmTheme artifact. Matching their mood requires separate design work and separate testing.

For the CLI workflow:

  1. Start an interactive Codex CLI session and run /theme.
  2. Try the picker’s available themes first.
  3. If you need a custom definition, obtain or author a .tmTheme file from a source you trust.
  4. Place that file in $CODEX_HOME/themes.
  5. Reopen /theme, select it, and verify code blocks and diffs in the terminal UI.

Do not paste a .tmTheme document into desktop Appearance, paste a codex-theme-v1: string into the terminal, or put the desktop string in $CODEX_HOME/themes.

Check safety before you copy, import, or save a file

Both paths are configuration artifacts, so provenance and boundaries still matter. For a desktop import, expect the exact codex-theme-v1: prefix followed by appearance JSON. Treat a value that includes shell commands, credentials, unrelated URLs, repository data, or instructions to run it as a reason to stop and recopy from a canonical source.

For a CLI .tmTheme, prefer a source you can identify and inspect before placing the file in your themes directory. Keep the file limited to the theme you chose; do not copy an entire $CODEX_HOME directory just to move one color scheme. That directory can contain settings unrelated to appearance.

Never paste either kind of theme artifact into a shell command, shell profile, repository file, or credential prompt. The desktop import string does not include font files or grant a font license. If it names a font, install a properly licensed copy separately or choose a local fallback, then verify legibility.

For a deeper review of the desktop payload and its limits, read Is DexThemes safe? and the Codex theme format reference. DexThemes is community-built and is not affiliated with OpenAI.

Keep downloads portable without mixing formats

Save desktop imports as plain-text backups labeled with the theme name, variant, and export date. Save a custom CLI .tmTheme file separately, plus a short note naming any built-in /theme selection you rely on. Share each artifact with instructions for its own surface rather than presenting either one as a universal installer.

Portability is not a compatibility guarantee. A different Codex version, operating system, display, or font installation can affect the result. After moving a theme, verify the desktop Appearance import and the CLI /theme selection independently, and keep a comfortable built-in fallback available.

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