Per-Project Extensions

Run VS Code with only the extensions a project needs, to save memory, CPU and startup time.

Each project declares its extensions in .vscode/required-extensions.json:

{
  "required": [
    "dbaeumer.vscode-eslint",
    "esbenp.prettier-vscode",
    "ms-python.python"
  ]
}

A bare array (["ms-python.python"]) also works. Only listed extensions stay enabled; everything else is disabled, including themes, icon themes, grammars and snippets. Add "keepDeclarativeExtensions": true to keep those code-less extensions (they cost almost nothing at runtime) without listing each one.

Always kept in addition to the list:

• this extension,
• dependencies (extensionDependencies) of required extensions,
• IDs in the projectExtensions.alwaysEnabled setting (handy in user settings for things you want everywhere, e.g. Copilot, Vim),
• built-in extensions (never touched).

How it's applied

The VS Code API can't enable or disable other extensions, so the extension uses the code CLI in one of two ways:

Both are scoped to this project only. Other folders keep your default profile with every extension enabled. If another folder ever ends up in a Project - … profile (for example via File > Open Folder from that window), it is detected on startup and you're offered to reopen it in the Default profile. To go back to all extensions for this project, run Reopen in Default Profile (All Extensions).

Both run a small detached helper after the window closes; its log is in the extension's global storage (relaunch.log).

Creating the file

When the extension is enabled and a folder has no .vscode/required-extensions.json, it creates one on startup listing every installed extension, so nothing is disabled until you trim the list.

• Per-Project Extensions: Review Required Extensions (or click the status bar item) shows every installed extension as a checklist and saves the checked ones to the file. If the file doesn't exist yet, the list is pre-filled by scanning the project: file languages, activationEvents (onLanguage, workspaceContains), package.json dependencies (eslint, prettier, vue, jest…), config files (Dockerfile, Cargo.toml, go.mod…), and .vscode/extensions.json recommendations.
• Detect Required Extensions From Project (Re-scan) ignores the existing file and suggests a list from scratch.
• Open required-extensions.json opens the file for editing. A JSON schema provides validation.

The file stays in sync automatically. Installing an extension while this project's window is focused adds it to required-extensions.json; uninstalling removes it, even when the extension keeps running until restart. Other open windows are left alone. In a project profile, changes made while the manager wasn't running are picked up the next time the window opens. Turn this off with projectExtensions.syncOnInstall.

On startup in a project with the file, if extensions that aren't listed are running, you're offered to switch. The status bar shows how many installed extensions aren't required.

Footprint

The extension is built to stay out of the way:

• It loads after startup finishes (onStartupFinished), so it never slows down opening a window.
• It never scans your project in the background. The file scan runs only when you run Detect or Review without a file.
• Two tiny watchers. One on required-extensions.json, one on the profile's installed-extensions list. No polling, no timers.
• One ~20 KB minified bundle. The relaunch helper is a separate short-lived process that exits when done.
• "Open in Project Profile" sets window.newWindowProfile to Default (unless you already set it). VS Code would otherwise give folders opened from a project-profile window that project's profile, so this keeps project profiles project-only without the extension having to run everywhere.

Settings

Limitations

• Only local folders and workspaces are supported; remote (SSH/WSL/containers) is not.
• Detection sees only extensions enabled in the current window. Extensions listed in the file but disabled or not installed are still installed into the project profile.
• A new profile window starts empty for a few seconds while the extensions install. If something looks missing, run Developer: Reload Window there.
• Settings copied into a new profile are a snapshot. Later changes to your default profile's settings aren't synced.

Develop

Set up following the official guides for bundling and testing. CI and releasing are described in PUBLISHING.md.

Debugging: press F5 (Run Extension). To run or debug single tests, install the recommended Extension Test Runner and use the Testing view.

Tests live in src/test/, compile to out/test/ (tests are not bundled) and open test-fixtures/test-project with all other extensions disabled.

Manual sandbox: a separate VS Code with its own settings and test extensions in .sandbox/, so you can try profiles and relaunching without touching your own setup.