Pre

A dark theme for VS Code. Neon accents on a neutral grey ramp, with every text pairing measured against WCAG AA.

Install

Search for Pre in the Extensions view, or run:

code --install-extension leandromatos.pre

How the theme is built

themes/Pre-color-theme.json is generated. Do not edit it. Every colour is decided in src/palette.ts, by role, and the rest of src/ maps those roles onto VS Code:

bun run build     # write themes/Pre-color-theme.json
bun run watch     # rebuild on save; VS Code reloads the theme with no window reload
bun run audit     # build, then check the result
bun run registry  # re-read the colour registry after a VS Code upgrade

What the audit checks

src/registry.json holds every colour id the installed VS Code registers, which of them must be transparent, and which are deprecated. scripts/extract-registry.ts reads it out of the shipped bundle and the built-in extension manifests, so the list matches the editor you are running rather than a documentation page. The published reference is behind: it still lists testing.message.error.decorationForeground, which 1.136 renamed.

The audit fails on a key VS Code no longer accepts, a deprecated key, an opaque colour on a key that paints over the code, and a value that is not a hex colour. Contrast is reported rather than gated, because closing a shortfall means changing a colour and that is a decision about how the theme looks: bun run audit --strict gates on it too.

Working on the theme

Symlink the folder instead of packaging it:

code --uninstall-extension leandromatos.pre
ln -s "$PWD/vs-code" ~/.vscode/extensions/leandromatos.pre-dev

VS Code watches the theme file and repaints on save, so bun run watch gives you the whole editor as the preview. bench/ holds one file per language worth checking, so you compare the same screen every time.

Two built-in commands do the rest. Developer: Generate Color Theme From Current Settings dumps every resolved key, including the ones you never set. Developer: Inspect Editor Tokens and Scopes tells you which scope owns the symbol under the cursor, which is the only reliable way to fix a syntax colour.

Licence

MIT. See LICENSE.

engines.vscode tracks the version src/registry.json was read from, because the theme sets keys that only exist from that version on. Re-run bun run registry after upgrading VS Code and the floor moves with it.