A .vsix is a packaged VS Code extension. Install one from the Downloads page when you want a specific version, an offline install, or a build that is not on the Marketplace yet.

From the Extensions view

  1. Download vscode-fson-<version>.vsix (and/or vscode-ffsmd-<version>.vsix) from Downloads.
  2. In VS Code, open the Extensions view (<kbd>Ctrl/Cmd</kbd>+<kbd>Shift</kbd>+<kbd>X</kbd>).
  3. Click the ⋯ menu at the top of the view → Install from VSIX….
  4. Pick the downloaded file. VS Code installs it and offers to reload.

From the command line

code --install-extension vscode-fson-0.10.0.vsix
code --install-extension vscode-ffsmd-0.8.0.vsix

(code is VS Code's CLI — on macOS, run Shell Command: Install 'code' command in PATH from the Command Palette first.)

Verify

Open any .fson file. The language indicator in the status bar should read FSON, and ---prefixed members should appear dimmed. Run Developer: Inspect Editor Tokens and Scopes to confirm the grammar is active (source.fson).

Updating

A .vsix install does not auto-update. To move to a newer version, download the new .vsix and install it the same way (it replaces the old one), or switch to the Marketplace version (code --install-extension Fedem.vscode-fson), which does auto-update.

Uninstall

Extensions view → find FSON / FFS-MD → gear icon → Uninstall. Or code --uninstall-extension Fedem.vscode-fson.