diff --git a/packages/@ant/ink/src/theme/ThemeProvider.tsx b/packages/@ant/ink/src/theme/ThemeProvider.tsx
index bfd6a4307..698a16076 100644
--- a/packages/@ant/ink/src/theme/ThemeProvider.tsx
+++ b/packages/@ant/ink/src/theme/ThemeProvider.tsx
@@ -92,7 +92,7 @@ export function ThemeProvider({
       if (activeSetting !== 'auto' || !internal_querier) return
       let cleanup: (() => void) | undefined
       let cancelled = false
-      void import('../../utils/systemThemeWatcher.js').then(
+      void import('../utils/systemThemeWatcher.js').then(
         ({ watchSystemTheme }) => {
           if (cancelled) return
           cleanup = watchSystemTheme(internal_querier, setSystemTheme)
diff --git a/packages/@ant/ink/src/utils/systemThemeWatcher.ts b/packages/@ant/ink/src/utils/systemThemeWatcher.ts
new file mode 100644
index 000000000..8d32c61fb
--- /dev/null
+++ b/packages/@ant/ink/src/utils/systemThemeWatcher.ts
@@ -0,0 +1,84 @@
+import type { Dispatch, SetStateAction } from 'react'
+import {
+  oscColor,
+  type TerminalQuerier,
+} from '../core/terminal-querier.js'
+import { setCachedSystemTheme, type SystemTheme } from '../theme/systemTheme.js'
+
+const BACKGROUND_COLOR = 11
+const POLL_INTERVAL_MS = 5_000
+
+export function watchSystemTheme(
+  querier: TerminalQuerier,
+  setTheme: Dispatch<SetStateAction<SystemTheme>>,
+): () => void {
+  let cancelled = false
+
+  async function poll(): Promise<void> {
+    const [response] = await Promise.all([
+      querier.send(oscColor(BACKGROUND_COLOR)),
+      querier.flush(),
+    ])
+    if (cancelled || !response) return
+
+    const theme = themeFromOscColor(response.data)
+    if (!theme) return
+
+    setCachedSystemTheme(theme)
+    setTheme(theme)
+  }
+
+  void poll()
+  const interval = setInterval(() => {
+    void poll()
+  }, POLL_INTERVAL_MS)
+
+  return () => {
+    cancelled = true
+    clearInterval(interval)
+  }
+}
+
+function themeFromOscColor(data: string): SystemTheme | undefined {
+  const rgb = parseOscRgb(data)
+  if (!rgb) return undefined
+
+  const luminance = 0.2126 * rgb.r + 0.7152 * rgb.g + 0.0722 * rgb.b
+  return luminance > 0.5 ? 'light' : 'dark'
+}
+
+type Rgb = {
+  r: number
+  g: number
+  b: number
+}
+
+function parseOscRgb(data: string): Rgb | undefined {
+  const rgbMatch =
+    /^rgba?:([0-9a-f]{1,4})\/([0-9a-f]{1,4})\/([0-9a-f]{1,4})/i.exec(data)
+  if (rgbMatch) {
+    return {
+      r: hexComponent(rgbMatch[1]!),
+      g: hexComponent(rgbMatch[2]!),
+      b: hexComponent(rgbMatch[3]!),
+    }
+  }
+
+  const hashMatch = /^#([0-9a-f]+)$/i.exec(data)
+  if (hashMatch && hashMatch[1]!.length % 3 === 0) {
+    const hex = hashMatch[1]!
+    const width = hex.length / 3
+    return {
+      r: hexComponent(hex.slice(0, width)),
+      g: hexComponent(hex.slice(width, 2 * width)),
+      b: hexComponent(hex.slice(2 * width)),
+    }
+  }
+
+  return undefined
+}
+
+function hexComponent(hex: string): number {
+  const max = 16 ** hex.length - 1
+  return parseInt(hex, 16) / max
+}
diff --git a/vite.config.ts b/vite.config.ts
index d42e67e6b..23d79105a 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -127,7 +127,7 @@ export default defineConfig({
   resolve: {
     alias: {
       // src/* path alias (mirrors tsconfig paths)
-      'src/': resolve(projectRoot, 'src/'),
+      src: resolve(projectRoot, 'src'),
     },
     // Ensure workspace packages share a single copy of these
     dedupe: ['react', 'react-reconciler', 'react-compiler-runtime'],