Environment variables

Every option except the three below also resolves from an environment variable with the LIT_PLUGIN prefix. Use them to switch dev-only tooling on per machine without editing vite.config.ts.

Env var	Maps to
`LIT_PLUGIN_HMR`	`hmr.enabled`
`LIT_PLUGIN_HMR_RECONNECT`	`hmr.reconnect`
`LIT_PLUGIN_HMR_PRIVATE_FIELDS`	`hmr.privateFields`
`LIT_PLUGIN_HMR_CHILD_STATE`	`hmr.childState`
`LIT_PLUGIN_HMR_ON_INCOMPATIBLE`	`hmr.onIncompatible`
`LIT_PLUGIN_HMR_INDICATOR`	`hmr.indicator.enabled`
`LIT_PLUGIN_HMR_INDICATOR_COUNT`	`hmr.indicator.count`
`LIT_PLUGIN_SOURCE_OVERLAY`	`sourceOverlay` (enable)
`LIT_PLUGIN_SOURCE_OVERLAY_KEY`	`sourceOverlay.key`
`LIT_PLUGIN_SOURCE_OVERLAY_EDITOR`	`sourceOverlay.editor`
`LIT_PLUGIN_SOURCE_OVERLAY_THROTTLE_MS`	`sourceOverlay.throttleMs`
`LIT_PLUGIN_TIMELINE`	`timeline` (enable)
`LIT_PLUGIN_CSS_SHEET_BUILD`	`cssSheetBuild`
`LIT_PLUGIN_DEVTOOLS_WORKSPACE`	`devtoolsWorkspace`

Precedence

Per setting, the value passed to litPlugin() wins over the environment variable, which wins over the built-in default.

Precedence applies to each setting on its own, not to the group it sits in. So litPlugin({hmr: {reconnect: true}}) fixes reconnect, and LIT_PLUGIN_HMR_INDICATOR_COUNT=1 still reaches the indicator.

A live override from the DevTools Settings tab sits above all three, for the settings it can change. The tab labels a value set by env or an option with its layer, such as Zed (env); a built-in default carries no label. While an override is active the row names the value it replaced, such as env: Zed, so you can tell what a reset restores.

How values are parsed

Booleans accept true, 1, false, and 0. Any other value counts as unset, and the option falls through to its default.
Numbers must parse as a number. LIT_PLUGIN_SOURCE_OVERLAY_THROTTLE_MS is the only one. An unparsable value counts as unset.
LIT_PLUGIN_CSS_SHEET_BUILD is checked against the four allowed values. Anything else logs a warning and falls back to the default.
LIT_PLUGIN_SOURCE_OVERLAY_EDITOR must name a built-in editor: vscode, cursor, zed, idea or windsurf. Anything else logs a warning and falls back to the default. A custom editor object can only be passed as the sourceOverlay.editor option.
LIT_PLUGIN_DEVTOOLS_WORKSPACE takes a boolean to turn the workspace reply on or off. Any other value is the folder to serve, relative to Vite’s root.

Options with no environment variable

Three options are config-only. sourceOverlay.exclude and sourceOverlay.onSelect are functions, and sourceOverlay.workspaceRoot is a path that belongs next to the rest of your build config.

Example

# Dev-only tooling, switched on without touching vite.config.ts.
LIT_PLUGIN_TIMELINE=true
LIT_PLUGIN_SOURCE_OVERLAY=true
LIT_PLUGIN_SOURCE_OVERLAY_EDITOR=zed
LIT_PLUGIN_SOURCE_OVERLAY_THROTTLE_MS=16
LIT_PLUGIN_HMR_INDICATOR_COUNT=1

The plugin reads these through Vite’s loadEnv, so they follow Vite’s usual .env resolution: .env, .env.local, and the mode-specific variants.

OptionsThe same surface as a config object, with defaults.

Open a component in your editorThe feature with the most env-configurable sub-options.