fix(code-mode): keep deep host boundaries iterative

packages/llm/llm/src/call-config.ts

@@ -58,7 +58,8 @@ export function isAgentLoopRequest(request: GenerateOptions): boolean {
 }
 
 /**
- * Deep-freeze a value in place, guarding cycles, so later mutation throws.
+ * Deep-freeze a value in place with an iterative traversal, guarding cycles,
+ * so later mutation throws without imposing a JavaScript call-stack depth cap.
  * {@link AbortSignal} objects are deliberately skipped because they are the
  * request's live cancellation channel and freezing them breaks abort.
  * @param value - the value to freeze in place.
@@ -66,16 +67,31 @@ export function isAgentLoopRequest(request: GenerateOptions): boolean {
  */
 export function deepFreeze<T>(value: T): T {
   const seen = new WeakSet<object>()
-  const walk = (node: unknown): void => {
-    if (node === null || typeof node !== 'object') return
-    if (node instanceof AbortSignal) return
-    if (seen.has(node)) return
+  const pending: (
+    | { kind: 'visit'; node: unknown }
+    | { kind: 'property'; source: Record<string, unknown>; key: string }
+  )[] = [{ kind: 'visit', node: value }]
+  while (pending.length > 0) {
+    const task = pending.pop()
+    /* v8 ignore next -- the loop condition guarantees one pending task. */
+    if (task === undefined) continue
+    if (task.kind === 'property') {
+      pending.push({ kind: 'visit', node: task.source[task.key] })
+      continue
+    }
+    const node = task.node
+    if (node === null || typeof node !== 'object') continue
+    if (node instanceof AbortSignal) continue
+    if (seen.has(node)) continue
     seen.add(node)
     Object.freeze(node)
-    for (const key of Object.keys(node)) {
-      walk((node as Record<string, unknown>)[key])
+    const keys = Object.keys(node)
+    for (let index = keys.length - 1; index >= 0; index--) {
+      const key = keys[index]
+      /* v8 ignore next -- the loop is bounded by the captured key count. */
+      if (key === undefined) continue
+      pending.push({ kind: 'property', source: node as Record<string, unknown>, key })
     }
   }
-  walk(value)
   return value
 }

packages/llm/llm/tests/call-config.spec.ts

@@ -56,6 +56,26 @@ describe('deepFreeze', () => {
     deepFreeze(cyclic)
     expect(Object.isFrozen(cyclic)).toBe(true)
   })
+
+  it('freezes nesting deeper than the JavaScript call stack', () => {
+    const depth = 5_000
+    const root: unknown[] = []
+    let cursor = root
+    for (let index = 0; index < depth; index++) {
+      const child: unknown[] = []
+      cursor.push(child)
+      cursor = child
+    }
+
+    deepFreeze(root)
+
+    cursor = root
+    for (let index = 0; index < depth; index++) {
+      expect(Object.isFrozen(cursor)).toBe(true)
+      cursor = cursor[0] as unknown[]
+    }
+    expect(Object.isFrozen(cursor)).toBe(true)
+  })
 })
 
 describe('agent-loop request identity', () => {