IntelliJ Platform New UI Icons

Guidance for authoring SVG icons for the New UI.

Background: the IDE maintains Classic UI and New UI in parallel. Code branches with ExperimentalUI.isNewUI(); icons follow the same split. Old icons stay in their original resource folders for Classic-UI compatibility. New-UI icons live under expui/ folders and are substituted for the old ones at runtime by icon mappers.

Golden rules

1. Always ship two SVGs — one for the light theme (e.g. addFile.svg) and one for the dark theme with the _dark suffix (addFile_dark.svg). Geometry must be identical between them; only the palette swaps.
   • Tool-window icons ship as a quartet, not a pair. When a tool window has both a 16×16 base (name.svg / name_dark.svg) and a 20×20 New-UI stripe variant (name@20x20.svg / name@20x20_dark.svg), they must share the same metaphor. The stripe is only one surface — the 16×16 base also appears in Search Everywhere, Find Action, context menus, the Services tool window, recent locations, and the View ▸ Tool Windows menu. Changing only the @20x20 leaves users seeing two different icons for the same tool window depending on where they encounter it. Always update all four files together (and the same applies to plugin-local icons like toolWindowChat.svg + toolWindowChat@20x20.svg).
2. Only use colors from the canonical palette. See palette.md. Picking a one-off color breaks theming and contrast.
3. One canvas size per icon role. See Icon roles. Do not invent new sizes or pad with empty space — IntelliJ scales the canvas as a single unit.
4. No raster, no gradients, no filters, no embedded fonts. Path geometry only (<path>, <rect>, <circle>, <line>, <polyline>, <polygon>). Text must be converted to outlines.
5. Use fill="none" on the root <svg> and set fill / stroke explicitly per shape — never rely on CSS or currentColor.
6. Strokes use stroke-width="1", stroke-linecap="round", stroke-linejoin="round" (or stroke-miterlimit="10" for hard joins). Heavier strokes are reserved for hero glyphs inside a circle badge (e.g. status checkmarks) and use stroke-width="1.5" or "2".
7. Pixel-grid align: keep stroke axes on half-pixel centers (x.5) and fills on whole pixels so the icon stays crisp at 1× rendering.
8. Preserve the Apache 2.0 copyright comment as line 1. Match the year of contribution.
9. File names use camelCase matching the action/node ID and stay ASCII-only.