use symbols to avoid enumeration of injected keys

src/node/config.ts

@@ -15,7 +15,7 @@ import type { DefaultTheme } from './defaultTheme'
 import { resolvePages } from './plugins/dynamicRoutesPlugin'
 import {
   APPEARANCE_KEY,
-  VP_SOURCE_KEY,
+  VP_CONFIG_SOURCE,
   isObject,
   slash,
   type AdditionalConfig,
@@ -219,7 +219,7 @@ async function gatherAdditionalConfig(
       )
 
       if (mode === 'development') {
-        ;(configExports.config as any)[VP_SOURCE_KEY] = '/' + slash(file)
+        ;(configExports.config as any)[VP_CONFIG_SOURCE] = '/' + slash(file)
       }
 
       return [id, configExports.config as AdditionalConfig] as const

src/shared/shared.ts

@@ -25,7 +25,11 @@ export type {
 export const EXTERNAL_URL_RE = /^(?:[a-z]+:|\/\/)/i
 export const APPEARANCE_KEY = 'vitepress-theme-appearance'
 
-export const VP_SOURCE_KEY = '[VP_SOURCE]'
+// Global symbols will be preserved by living-object.
+export const VP_CONFIG_SOURCE = Symbol.for('VP:ConfigSource')
+export const VP_CLIENT_ONLY = Symbol.for('VP:ClientOnly')
+// Private symbols are distinct in each runtime environment.
+// This should only be used internally.
 const UnpackStackView = Symbol('stack-view:unpack')
 
 const HASH_RE = /#.*$/
@@ -111,7 +115,7 @@ export function resolveSiteDataByRoute(
   const additionalConfigs = resolveAdditionalConfig(siteData, relativePath)
 
   if (inBrowser && (import.meta as any).env?.DEV) {
-    ;(localeConfig as any)[VP_SOURCE_KEY] = `locale config (${localeIndex})`
+    ;(localeConfig as any)[VP_CONFIG_SOURCE] = `locale config (${localeIndex})`
     reportConfigLayers(relativePath, [
       ...additionalConfigs,
       localeConfig,
@@ -296,7 +300,7 @@ function reportConfigLayers(path: string, layers: Partial<SiteData>[]) {
   const summary = layers.map((c, i, arr) => {
     const n = i + 1
     if (n === arr.length) return `${n}. .vitepress/config (root)`
-    return `${n}. ${(c as any)?.[VP_SOURCE_KEY] ?? '(Unknown Source)'}`
+    return `${n}. ${(c as any)?.[VP_CONFIG_SOURCE] ?? '(Unknown Source)'}`
   })
 
   console.debug(
@@ -353,15 +357,13 @@ export function isObject(value: unknown): value is ObjectType {
   return Object.prototype.toString.call(value) === '[object Object]'
 }
 
-const ClientOnlyMarker = Symbol.for('vitepress:client-only')
-
 export function clientOnly<T extends object>(object: T) {
-  ;(object as any)[ClientOnlyMarker] = true
+  ;(object as any)[VP_CLIENT_ONLY] = true
   return object
 }
 
 export function isClientOnly<T extends object>(object?: T): boolean {
-  return (object as any)?.[ClientOnlyMarker] ?? false
+  return (object as any)?.[VP_CLIENT_ONLY] ?? false
 }
 
 export function propagateClientOnly<T extends object>(src: T, dst: T): T {