diff --git a/changelog.md b/changelog.md
index 9cc9662..4f2ba83 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 2025-09-12 - 5.2.0 - feat(smartjson)
+Implement stableOneWayStringify: deterministic, cycle-safe JSON for hashing/comparisons; update docs and tests
+
+- Implement stableOneWayStringify in ts/index.ts: produces deterministic JSON, encodes buffers, replaces circular references with "__cycle__" and marks unserializable values as "__unserializable__".
+- Update README: add documentation and examples for stableOneWayStringify, clarify JSONL wording, and update performance/migration notes.
+- Add unit test to verify stableOneWayStringify handles circular references without throwing.
+- Add .claude/settings.local.json (local settings/config) as part of the change set.
+
 ## 2025-09-12 - 5.1.0 - feat(smartjson)
 Add JSONL stringify and ordering comparator; fix empty buffer handling; refactor Smartjson folding/enfolding
 
diff --git a/readme.md b/readme.md
index 966dfbb..bb61b81 100644
--- a/readme.md
+++ b/readme.md
@@ -21,9 +21,10 @@ pnpm add @push.rocks/smartjson
 ✨ **Type-Safe JSON Operations** - Full TypeScript support with proper typing  
 🎯 **Class Instance Serialization** - Fold and unfold class instances to/from JSON  
 🔐 **Buffer & Binary Support** - Seamless handling of Buffers and Typed Arrays  
-📊 **JSON Lines Support** - Parse and compare JSONL data streams  
+📊 **JSON Lines Support** - Parse, stringify and compare JSONL data streams  
 🎨 **Pretty Printing** - Beautiful formatted JSON output  
 ⚡ **Stable Stringification** - Consistent key ordering for reliable comparisons  
+♻️ **Circular Reference Handling** - Safe one-way stringify for objects with cycles  
 🔍 **Deep Equality Checks** - Compare complex objects and JSON structures  
 🌐 **Base64 Encoding** - Built-in base64 JSON encoding/decoding  
 
@@ -67,6 +68,40 @@ const prettyJson = smartjson.stringifyPretty({
 });
 ```
 
+### Safe One-Way Stringification (New in v5.1.0)
+
+Handle circular references and unserializable values safely for hashing and comparisons:
+
+```typescript
+// Create objects with circular references
+const objA = { name: 'A' };
+const objB = { name: 'B', ref: objA };
+objA['ref'] = objB; // Circular reference!
+
+// Normal stringify would throw, but stableOneWayStringify handles it
+const safeJson = smartjson.stableOneWayStringify(objA);
+// Circular references are replaced with "__cycle__"
+
+// Perfect for object hashing
+const hash1 = crypto.createHash('sha256')
+  .update(smartjson.stableOneWayStringify(complexObject))
+  .digest('hex');
+
+// Handles unserializable values gracefully
+const objWithGetter = {
+  normal: 'value',
+  get throwing() { throw new Error('Cannot serialize!'); }
+};
+const safe = smartjson.stableOneWayStringify(objWithGetter);
+// Throwing getters are replaced with "__unserializable__"
+
+// Custom key ordering for consistent hashes
+const ordered = smartjson.stableOneWayStringify(
+  { z: 1, a: 2 },
+  ['a', 'z'] // Specify key order
+);
+```
+
 ### Base64 JSON Encoding
 
 Encode JSON data as base64 for safe transmission:
@@ -311,6 +346,7 @@ class AppConfig extends Smartjson {
 
 - `parse(jsonString: string): any` - Parse JSON with automatic buffer handling
 - `stringify(obj: any, simpleOrderArray?: string[], options?: Options): string` - Convert to JSON with stable ordering
+- `stableOneWayStringify(obj: any, simpleOrderArray?: string[], options?: Options): string` - Safe stringify with circular reference handling (one-way, for hashing/comparison)
 - `stringifyPretty(obj: any): string` - Pretty print JSON with 2-space indentation
 - `stringifyBase64(obj: any): string` - Encode JSON as base64
 - `parseBase64(base64String: string): any` - Decode base64 JSON
@@ -336,7 +372,8 @@ class AppConfig extends Smartjson {
 2. **Enable pretty printing** only for debugging (it's slower)
 3. **Cache base64 encodings** when repeatedly sending the same data
 4. **Use JSON Lines** for streaming large datasets
-5. **Avoid circular references** in objects being serialized
+5. **Use stableOneWayStringify** for objects with circular references (for hashing/caching)
+6. **Prefer regular stringify** for round-trip serialization without cycles
 
 ## Migration Guide
 
diff --git a/test/test.both.ts b/test/test.both.ts
index 66e89ae..ba03445 100644
--- a/test/test.both.ts
+++ b/test/test.both.ts
@@ -104,4 +104,15 @@ tap.test('should respect simpleOrderArray comparator', async () => {
   expect(ordered.indexOf('"a"')).toBeLessThan(ordered.indexOf('"c"'));
 });
 
+tap.test('stableOneWayStringify should handle circular references without throwing', async () => {
+  const a: any = { name: 'x' };
+  a.self = a;
+  const b: any = { name: 'x' };
+  b.self = b;
+  const s1 = smartjson.stableOneWayStringify(a);
+  const s2 = smartjson.stableOneWayStringify(b);
+  expect(typeof s1).toEqual('string');
+  expect(s1).toEqual(s2);
+});
+
 tap.start();
diff --git a/ts/00_commitinfo_data.ts b/ts/00_commitinfo_data.ts
index 7749be9..860ef3e 100644
--- a/ts/00_commitinfo_data.ts
+++ b/ts/00_commitinfo_data.ts
@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartjson',
-  version: '5.1.0',
+  version: '5.2.0',
   description: 'A library for handling typed JSON data, providing functionalities for parsing, stringifying, and working with JSON objects, including support for encoding and decoding buffers.'
 }
diff --git a/ts/index.ts b/ts/index.ts
index 63cb09a..9f0f8c6 100644
--- a/ts/index.ts
+++ b/ts/index.ts
@@ -26,6 +26,69 @@ export const stringifyJsonL = (items: any[]): string => {
   return items.map((item) => stringify(item)).join('\n');
 }
 
+/**
+ * stableOneWayStringify
+ * - Produces a stable, deterministic JSON string
+ * - Handles circular references without throwing (replaces cycles)
+ * - Safe for hashing/comparisons ("one-way"; not intended for round-trips)
+ */
+export const stableOneWayStringify = (
+  objArg: any,
+  simpleOrderArray?: string[],
+  optionsArg: plugins.IStableJsonTypes['Options'] = {}
+): string => {
+  // Prepare object without throwing on circular references, and encode buffers
+  const visited = new WeakSet<object>();
+  const sanitize = (val: any): any => {
+    // primitives
+    if (val === null || typeof val !== 'object') {
+      return val;
+    }
+    // Encode buffers/typed arrays via existing replacer
+    const replaced = (bufferhandling.replacer as any)('', val);
+    if (replaced && replaced.type === 'EncodedBuffer' && typeof replaced.data === 'string') {
+      return replaced;
+    }
+    // Handle circular references
+    if (visited.has(val)) {
+      return '__cycle__';
+    }
+    visited.add(val);
+    // Arrays
+    if (Array.isArray(val)) {
+      return val.map((item) => sanitize(item));
+    }
+    // Plain objects and class instances: copy enumerable own props
+    const out: Record<string, any> = {};
+    for (const key of Object.keys(val)) {
+      try {
+        out[key] = sanitize((val as any)[key]);
+      } catch (e) {
+        // In case of getters throwing or non-serializable, mark
+        out[key] = '__unserializable__';
+      }
+    }
+    return out;
+  };
+
+  const obj = sanitize(objArg);
+  const options: plugins.IStableJsonTypes['Options'] = {
+    ...optionsArg,
+    cycles: true,
+  };
+  if (simpleOrderArray && !options.cmp) {
+    const order = new Map<string, number>();
+    simpleOrderArray.forEach((key, idx) => order.set(key, idx));
+    options.cmp = (a, b) => {
+      const aIdx = order.has(a.key) ? (order.get(a.key) as number) : Number.POSITIVE_INFINITY;
+      const bIdx = order.has(b.key) ? (order.get(b.key) as number) : Number.POSITIVE_INFINITY;
+      if (aIdx !== bIdx) return aIdx - bIdx;
+      return a.key < b.key ? -1 : a.key > b.key ? 1 : 0;
+    };
+  }
+  return plugins.stableJson(obj, options);
+}
+
 /**
  *
  * @param objArg