refactor: use structured clone for local copies

extensions/telegram/src/bot.create-telegram-bot.test-harness.ts

@@ -80,7 +80,7 @@ export function getLoadSessionStoreMock(): AnyMock {
 }
 
 export function setSessionStoreEntriesForTest(entries: SessionStore) {
-  sessionStoreEntries.value = JSON.parse(JSON.stringify(entries)) as SessionStore;
+  sessionStoreEntries.value = structuredClone(entries);
 }
 
 const { readChannelAllowFromStore, upsertChannelPairingRequest } = vi.hoisted(

src/agents/pi-embedded-runner/compact.hooks.harness.ts

@@ -240,11 +240,7 @@ export async function loadCompactHooksHarness(): Promise<{
     createAgentSession: vi.fn(async () => {
       const session = {
         sessionId: "session-1",
-        messages: sessionMessages.map((message) =>
-          typeof structuredClone === "function"
-            ? structuredClone(message)
-            : JSON.parse(JSON.stringify(message)),
-        ),
+        messages: sessionMessages.map((message) => structuredClone(message)),
         agent: {
           streamFn: vi.fn(),
           transport: "sse",
@@ -253,7 +249,7 @@ export async function loadCompactHooksHarness(): Promise<{
               return session.messages;
             },
             set messages(messages: unknown[]) {
-              session.messages = [...(messages as typeof session.messages)];
+              session.messages = [...messages];
             },
           },
         },

src/commands/models.set.e2e.test.ts

@@ -10,7 +10,7 @@ vi.mock("./models/shared.js", async () => {
   return {
     ...actual,
     updateConfig: async (mutator: (cfg: Record<string, unknown>) => Record<string, unknown>) => {
-      const next = mutator(JSON.parse(JSON.stringify(mocks.currentConfig)));
+      const next = mutator(structuredClone(mocks.currentConfig));
       mocks.writtenConfig = next;
       return next;
     },

src/config/schema.shared.ts

@@ -9,10 +9,7 @@ type JsonSchemaObject = {
 };
 
 export function cloneSchema<T>(value: T): T {
-  if (typeof structuredClone === "function") {
-    return structuredClone(value);
-  }
-  return JSON.parse(JSON.stringify(value)) as T;
+  return structuredClone(value);
 }
 
 export function asSchemaObject(value: unknown): object | null {

src/cron/isolated-agent/run.cron-model-override.test.ts

@@ -147,7 +147,7 @@ describe("runCronIsolatedAgentTurn — cron model override (#21057)", () => {
           | { model?: string; modelProvider?: string; systemSent?: boolean }
           | undefined;
         if (entry) {
-          persistedSnapshots.push(JSON.parse(JSON.stringify(entry)));
+          persistedSnapshots.push(structuredClone(entry));
         }
       },
     );

src/cron/service/ops.ts

@@ -579,7 +579,7 @@ async function prepareManualRun(
       job,
       startedAt: preflight.now,
     });
-    const executionJob = JSON.parse(JSON.stringify(job)) as CronJob;
+    const executionJob = structuredClone(job);
     return {
       ok: true,
       ran: true,

src/gateway/cli-session-history.claude.ts

@@ -100,7 +100,7 @@ function resolveClaudeCliUsage(raw: ClaudeCliUsage) {
 }
 
 function cloneJsonValue<T>(value: T): T {
-  return JSON.parse(JSON.stringify(value)) as T;
+  return structuredClone(value);
 }
 
 function normalizeClaudeCliContent(

ui/src/ui/controllers/config/form-utils.ts

@@ -1,8 +1,5 @@
 export function cloneConfigObject<T>(value: T): T {
-  if (typeof structuredClone === "function") {
-    return structuredClone(value);
-  }
-  return JSON.parse(JSON.stringify(value)) as T;
+  return structuredClone(value);
 }
 
 export function serializeConfigForm(form: Record<string, unknown>): string {