fix: address structural truncation review comments

packages/core/src/telemetry/trace.test.ts

@@ -86,6 +86,56 @@ describe('truncateForTelemetry', () => {
     );
   });
 
+  it('should handle objects with a toJSON method', () => {
+    const date = new Date('2026-04-13T00:00:00.000Z');
+    const result = truncateForTelemetry(date);
+    expect(result).toBe('2026-04-13T00:00:00.000Z');
+  });
+
+  it('should handle getters via direct property access', () => {
+    const obj = {
+      get myGetter() {
+        return 'getter value';
+      },
+      get errorGetter() {
+        throw new Error('getter error');
+      },
+    };
+    const result = truncateForTelemetry(obj);
+    expect(result).toBe(
+      JSON.stringify({
+        myGetter: 'getter value',
+        errorGetter: '[ERROR: Failed to read property]',
+      }),
+    );
+  });
+
+  it('should truncate extremely long keys', () => {
+    const longKey = 'a'.repeat(150);
+    const obj = {
+      [longKey]: 'value',
+    };
+    const result = truncateForTelemetry(obj);
+    const expectedKey = 'a'.repeat(100) + '...[TRUNCATED_KEY]';
+    expect(result).toBe(
+      JSON.stringify({
+        [expectedKey]: 'value',
+      }),
+    );
+  });
+
+  it('should enforce a global payload string limit', () => {
+    const obj = {
+      a: 'x'.repeat(100),
+      b: 'y'.repeat(100),
+    };
+    // Let's cap global string length to 50
+    const result = truncateForTelemetry(obj, 100, 100, 4, 50) as string;
+    expect(result.length).toBeGreaterThan(50);
+    expect(result).toContain('...[TRUNCATED: original payload length');
+    expect(result.startsWith('{"a":"xxxx')).toBe(true);
+  });
+
   it('should stringify objects unchanged if within maxLength', () => {
     const obj = { a: 1 };
     expect(truncateForTelemetry(obj, 100)).toBe(JSON.stringify(obj));

packages/core/src/telemetry/trace.ts

@@ -44,6 +44,17 @@ export const spanRegistry = new FinalizationRegistry((endSpan: () => void) => {
   }
 });
 
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null;
+}
+
+function isHasToJSON(value: unknown): value is { toJSON: () => unknown } {
+  if (!isRecord(value)) return false;
+  if (!('toJSON' in value)) return false;
+  const toJSONFn = value['toJSON'];
+  return typeof toJSONFn === 'function';
+}
+
 /**
  * Truncates a value for inclusion in telemetry attributes.
  *
@@ -56,6 +67,7 @@ export function truncateForTelemetry(
   maxStringLength = 10000,
   maxArrayLength = 100,
   maxDepth = 4,
+  maxGlobalStringLength = 50000,
 ): AttributeValue | undefined {
   const truncateObj = (v: unknown, depth: number): unknown => {
     if (typeof v === 'string') {
@@ -76,6 +88,13 @@ export function truncateForTelemetry(
     ) {
       return v;
     }
+    if (isHasToJSON(v)) {
+      try {
+        return truncateObj(v.toJSON(), depth);
+      } catch {
+        // Ignore and fall back to manual structural iteration
+      }
+    }
     if (typeof v === 'object') {
       if (depth >= maxDepth) {
         return `[TRUNCATED: Max Depth Reached]`;
@@ -94,15 +113,20 @@ export function truncateForTelemetry(
       const newObj: Record<string, unknown> = {};
       let numKeys = 0;
       const MAX_KEYS = 100;
-      for (const key in v) {
-        if (!Object.prototype.hasOwnProperty.call(v, key)) continue;
+      const recordV = isRecord(v) ? v : {};
+      for (const key in recordV) {
+        if (!Object.prototype.hasOwnProperty.call(recordV, key)) continue;
         if (numKeys >= MAX_KEYS) {
           newObj['__truncated'] = `[TRUNCATED: Object with >${MAX_KEYS} keys]`;
           break;
         }
-        const descriptor = Object.getOwnPropertyDescriptor(v, key);
-        if (descriptor) {
-          newObj[key] = truncateObj(descriptor.value, depth + 1);
+        try {
+          const val = recordV[key];
+          const truncatedKey =
+            key.length > 100 ? key.slice(0, 100) + '...[TRUNCATED_KEY]' : key;
+          newObj[truncatedKey] = truncateObj(val, depth + 1);
+        } catch {
+          newObj[key] = '[ERROR: Failed to read property]';
         }
         numKeys++;
       }
@@ -124,7 +148,16 @@ export function truncateForTelemetry(
     return undefined;
   }
 
-  return safeJsonStringify(truncated) as AttributeValue;
+  const stringified = safeJsonStringify(truncated);
+  if (stringified.length > maxGlobalStringLength) {
+    const graphemes = Array.from(stringified);
+    if (graphemes.length > maxGlobalStringLength) {
+      return (graphemes.slice(0, maxGlobalStringLength).join('') +
+        `...[TRUNCATED: original payload length ${graphemes.length}]`) as AttributeValue;
+    }
+  }
+
+  return stringified as AttributeValue;
 }
 
 function isAsyncIterable<T>(value: T): value is T & AsyncIterable<unknown> {