fix(code-runtime): align worker JSON snapshots

packages/code-runtime/code-runtime-worker/src/worker-json.ts

@@ -2,6 +2,31 @@
 
 import type { CodeJsonValue } from '@deepseek-ai/dsh-code-runtime'
 
+/* jscpd:ignore-start -- the source worker mirrors session JSON helpers without workspace runtime imports */
+/** Whether an array uses one realm's intrinsic `Array.prototype`, not a subclass or forged prototype. */
+function hasPlainArrayPrototype(value: unknown[]): boolean {
+  const prototype: unknown = Object.getPrototypeOf(value)
+  if (!Array.isArray(prototype)) return false
+  const objectPrototype: unknown = Object.getPrototypeOf(prototype)
+  return objectPrototype !== null
+    && !Array.isArray(objectPrototype)
+    && Object.getPrototypeOf(objectPrototype) === null
+}
+
+/** Whether an object is a plain or null-prototype record from any JavaScript realm. */
+function hasPlainObjectPrototype(value: object): boolean {
+  const prototype: unknown = Object.getPrototypeOf(value)
+  return prototype === null || Object.getPrototypeOf(prototype) === null
+}
+
+/** Return every JSON-visible object key, or reject own data JSON would discard. */
+function enumerableStringKeys(value: object): string[] | undefined {
+  const keys = Reflect.ownKeys(value)
+  if (keys.some(key => typeof key !== 'string' || !Object.prototype.propertyIsEnumerable.call(value, key))) return undefined
+  return keys as string[]
+}
+/* jscpd:ignore-end */
+
 /**
  * Validate and detach one worker-boundary value without loading another
  * workspace package at runtime. This mirrors the session-owned canonical
@@ -32,11 +57,12 @@ export function snapshotCodeJsonValue(value: unknown): CodeJsonValue | undefined
     if (typeof candidate !== 'object') return undefined
 
     if (Array.isArray(candidate)) {
-      if (Object.getPrototypeOf(candidate) !== Array.prototype) return undefined
-      if (Reflect.ownKeys(candidate).length !== candidate.length + 1) return undefined
+      if (!hasPlainArrayPrototype(candidate)) return undefined
+      const length = candidate.length
+      if (Reflect.ownKeys(candidate).length !== length + 1) return undefined
       return within(candidate, () => {
         const result: CodeJsonValue[] = []
-        for (let index = 0; index < candidate.length; index++) {
+        for (let index = 0; index < length; index++) {
           if (!Object.hasOwn(candidate, index)) return undefined
           const item = copy(candidate[index])
           if (item === undefined) return undefined
@@ -46,11 +72,12 @@ export function snapshotCodeJsonValue(value: unknown): CodeJsonValue | undefined
       })
     }
 
-    const prototype = Object.getPrototypeOf(candidate) as unknown
-    if (prototype !== Object.prototype && prototype !== null) return undefined
+    if (!hasPlainObjectPrototype(candidate)) return undefined
+    const keys = enumerableStringKeys(candidate)
+    if (keys === undefined) return undefined
     return within(candidate, () => {
       const result: Record<string, CodeJsonValue> = {}
-      for (const key of Object.keys(candidate)) {
+      for (const key of keys) {
         const item = copy((candidate as Record<string, unknown>)[key])
         if (item === undefined) return undefined
         Object.defineProperty(result, key, {