Codespaces not saving extensions/settings between sessions

[evelyny72]

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Hi all,

I’ve been experimenting with GitHub Codespaces for a new project, and I’ve run into something confusing. Every time I reopen a codespace, some of my VS Code extensions and custom settings (like themes and editor config) don’t seem to stick. I end up reinstalling or reconfiguring them each time, which makes the workflow feel a bit clunky.

I’ve already tried:

Saving settings in .devcontainer/devcontainer.json

Using dotfiles with a repo linked in my account settings

Manually reinstalling extensions inside the codespace

But even after doing this, not everything persists. It’s possible I’m setting up the dotfiles incorrectly, or missing a step with how Codespaces handles personalization.

My questions are:

What’s the proper way to ensure extensions and settings persist across all Codespaces?

Should this be handled entirely through dotfiles, or is there a built-in way to sync like regular VS Code does?

If I’m using .devcontainer, is there a “best practice” for specifying extensions/settings there?

Any advice or examples would be super helpful. I just want to make sure I’m setting things up the right way instead of fighting against the platform.

Thanks!

[Hryhorii83]

[jfullstackdev]

I also personally observed things, though some of my observations might not be correct, here is the list :

• fresh container on each start

  • Codespaces rebuild from the .devcontainer.json.
  • If you install extensions manually inside a running codespace, they disappear on rebuild because they’re not in config.

• only using .devcontainer.json for container, not VS Code

  • The file defines dev environment (image, tools, etc.), but VS Code-specific extensions/settings must go under customizations.vscode.
  • If missing, your editor setup resets each time.

• relying on .vscode/settings.json alone

  • Stores workspace settings (e.g., formatting rules) in repo.
  • Doesn’t auto-install extensions : only applies settings if extensions are already present.

• using Dotfiles repo

  • Great for shell config (aliases, Zsh, custom scripts).
  • Doesn’t manage VS Code extensions/themes. You’ll still lose them unless added elsewhere.

• using VS Code Settings Sync

  • Works when opening Codespaces from the desktop client : syncs extensions & themes.
  • In the browser version, sync is limited (applies once at creation, doesn’t keep everything in sync).

bottom line is

you need a combo → put required extensions in .devcontainer.json, project settings in .vscode/settings.json, personal shell tweaks in dotfiles, and optionally enable Settings Sync for desktop

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note: if some settings are problematic, but the settings are minimal, like it's easier to manually setup after the Codespaces, then let it be,

remember, Codespaces is a disposable but once a single instance is successful, then we don't delete this from time to time in the same device, right ? it does not even delete itself if you continuously use it

changing laptops or places are not day to day scenario, so some problematic setting can be manual

think of it like a local clone of what we are working with, once we have that, we use that clone always, so regularly creating a new instance of a Codespace is not a day to day scenario too, so minimal manual is acceptable

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also personally, I have develop Codespaces for dev in Laravel and MERN, feel free !

https://github.com/jfullstackdev/codespaces-template-mern

https://github.com/jfullstackdev/codespaces-template-laravel

[AlvaroRausell]

@evelyny72 Hi! Codespaces team here. You are able to enable VS Code sync. You need to ensure this box is checked in your settings page:

Hope this helps!

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