Yozora「夜空」🌙

Bringing dark mode to PDFs in VS Code.

See the changelog for release highlights.

Using Yozora

Install

Download the VSIX package from the latest release, then install it in VS Code:

1. Open the View menu and select Command Palette.
2. Run Extensions: Install from VSIX... and select yozora-<version>.vsix.
3. Reload VS Code if prompted.

Install updates by selecting a newer VSIX the same way.

Open a PDF

Run Yozora: Open PDF from the Command Palette, or right-click a PDF, choose Open With..., and select Yozora PDF Viewer.

Turn dark mode on or off using the toggle in the editor title bar.

To use Yozora by default:

1. Run Preferences: Open Settings (UI) from the Command Palette.
2. Select the User tab and search for workbench.editorAssociations.
3. Under Workbench: Editor Associations, click Add Item.
4. Enter *.pdf for Key, select yozora.pdf from the Value dropdown, and click OK. If *.pdf is already listed, edit its value instead.
5. Close and reopen any PDFs that are already open.

Choose a theme

Theme	Appearance
Midnight (default)	Bright text against a moonless sky.
Graphite	Light gray text on charcoal, with gentler contrast.
Dracula	Off-white text on Dracula’s blue-gray background.

Use the theme button in the editor title bar, or run Yozora: Choose PDF Theme, to change themes.

Dracula uses the Dracula for VS Code palette: #282A36 for the page background and #F8F8F2 for text. Set yozora.defaultTheme to dracula to use it by default. All dark themes transform the entire PDF page, including figures; toggle dark mode off to view original colors.

Settings

Open VS Code Settings and search for yozora.

Setting	Default	Purpose
yozora.defaultTheme	midnight	Set the default theme.
yozora.defaultMode	dark	Set the default display mode.
yozora.maxFileSizeMiB	100	Set the maximum PDF size Yozora can open, in MiB.

Development

Setup

First, install mise and activate it in your shell. Then install Node.js and npm by running:

mise install

Install the dependencies and compile the project:

npm ci
npm run build    # Compile and bundle source files into dist/

Testing

To test manually:

1. Open the project folder in VS Code.
2. Open the View menu and select Run.
3. In the panel that opens, select Run Yozora from the dropdown at the top.
4. Click the green play button to the left of that dropdown. VS Code compiles the project and opens a new Extension Development Host window with Yozora loaded.
5. In that window, open the Command Palette and run Yozora: Open PDF.

Use npm run watch to recompile as you edit, then run Developer: Reload Window in the development window to load the changes.

Run the automated checks with:

npm run check

This checks the code and benchmark files, compiles the project, and runs unit tests.

For changes that affect rendering or VS Code integration, also run:

npx playwright install chromium    # Install the test browser
npm run test:papers                # Rendering and viewer behavior
npm run test:integration           # VS Code integration

See the paper benchmark for test coverage and screenshot comparisons.

Licenses

Yozora's source code is licensed under the MIT License.