diff --git a/apps/web/src/vscodeThemeImport.test.ts b/apps/web/src/vscodeThemeImport.test.ts
index 59f732bf4a12975c65206d4fae3817e5b0597d6f..797346a6557b6c608d60c291c8b0e43536986f1a 100644
--- a/apps/web/src/vscodeThemeImport.test.ts
+++ b/apps/web/src/vscodeThemeImport.test.ts
@@ -112,6 +112,36 @@ describe("VS Code theme import", () => {
     );
   });
 
+  it("moves reserved VS Code names to a non-reserved id", () => {
+    const darkPlus = parseVsCodeThemeFile({
+      name: "Dark+",
+      type: "dark",
+      colors: { "editor.background": "#1e1e1e" },
+    });
+    expect(darkPlus.label).toBe("Dark+");
+    expect(darkPlus.id).not.toBe("dark");
+    expect(darkPlus.id).toBe("dark-vscode");
+  });
+
+  it("keeps Dark+ and Light+ as separate themes instead of pairing them as +", () => {
+    const themes = pairVsCodeThemes([
+      parseVsCodeThemeFile({
+        name: "Light+",
+        type: "light",
+        colors: { "editor.background": "#ffffff" },
+      }),
+      parseVsCodeThemeFile({
+        name: "Dark+",
+        type: "dark",
+        colors: { "editor.background": "#1e1e1e" },
+      }),
+    ]);
+    expect(themes.map((theme) => [theme.id, theme.label])).toEqual([
+      ["light-vscode", "Light+"],
+      ["dark-vscode", "Dark+"],
+    ]);
+  });
+
   it("fills every role the file omits with a readable derived value", () => {
     const theme = parseVsCodeThemeFile(VSCODE_DARK);
     const colors = getThemeColorsForMode(theme, "dark")!;
diff --git a/apps/web/src/vscodeThemeImport.ts b/apps/web/src/vscodeThemeImport.ts
index 186e03fb6a34d926373045f9020a75bcf3926073..fc0fc2bf8cbc5e7e1326d52b45910c0adbf18c48 100644
--- a/apps/web/src/vscodeThemeImport.ts
+++ b/apps/web/src/vscodeThemeImport.ts
@@ -1,8 +1,10 @@
 import {
   createVividThemeColors,
   getThemeModes,
+  isReservedThemeId,
   parseThemeFile,
   themeColorToHex,
+  themeIdFromName,
   THEME_FILE_VERSION,
   type ThemeAppearance,
   type ThemeColorRole,
@@ -321,9 +323,12 @@ export function parseVsCodeThemeFile(value: unknown): ThemeDefinition {
 
   // Reuse the theme-file parser so ids, names, and color values go through the
   // same validation as a hand-written file.
+  const name = resolveName(value);
+  const generatedId = themeIdFromName(name);
   return parseThemeFile({
     version: THEME_FILE_VERSION,
-    name: resolveName(value),
+    ...(isReservedThemeId(generatedId) ? { id: `${generatedId}-vscode` } : {}),
+    name,
     appearance,
     colors: { ...derived, ...overrides },
   });
@@ -352,9 +357,11 @@ export function pairVsCodeThemes(
   const passthrough: Array<{ theme: ThemeDefinition; order: number }> = [];
   themes.forEach((theme, order) => {
     // Only single-appearance themes with an appearance word in the name can
-    // pair; anything else is already what the user asked for.
+    // pair, and only when the rest of the name can still identify the pair
+    // ("Dark+" and "Light+" would pair as "+"); anything else is already
+    // what the user asked for.
     const key = stripAppearance(theme.label);
-    if (getThemeModes(theme).length !== 1 || key === theme.label || key.length === 0) {
+    if (getThemeModes(theme).length !== 1 || key === theme.label || !/[a-z0-9]/i.test(key)) {
       passthrough.push({ theme, order });
       return;
     }