feat: implement stability fixes and enhance error handling

src/tests/unit/signature-utils.test.ts

@@ -0,0 +1,48 @@
+import { describe, it, expect } from 'vitest';
+import { decodeSignature } from '../../lib/antigravity/signature-utils';
+
+describe('decodeSignature', () => {
+  describe('Base64 decoding', () => {
+    it('should correctly decode valid Base64 signature', () => {
+      const original = 'valid-thinking-signature-12345';
+      const base64 = Buffer.from(original).toString('base64');
+      expect(decodeSignature(base64)).toBe(original);
+    });
+
+    it('should decode signature with special characters', () => {
+      const original = 'sig+with/special=chars==';
+      const base64 = Buffer.from(original).toString('base64');
+      expect(decodeSignature(base64)).toBe(original);
+    });
+
+    it('should decode UTF-8 Chinese signature', () => {
+      const original = '思考签名-测试';
+      const base64 = Buffer.from(original).toString('base64');
+      expect(decodeSignature(base64)).toBe(original);
+    });
+  });
+
+  describe('Non-Base64 passthrough', () => {
+    it('should return non-Base64 strings as-is', () => {
+      expect(decodeSignature('plain-text-signature')).toBe('plain-text-signature');
+    });
+
+    it('should handle strings with invalid Base64 characters', () => {
+      expect(decodeSignature('not!valid@base64#')).toBe('not!valid@base64#');
+    });
+  });
+
+  describe('Empty value handling', () => {
+    it('should return undefined for null input', () => {
+      expect(decodeSignature(null)).toBeUndefined();
+    });
+
+    it('should return undefined for undefined input', () => {
+      expect(decodeSignature(undefined)).toBeUndefined();
+    });
+
+    it('should return undefined for empty string', () => {
+      expect(decodeSignature('')).toBeUndefined();
+    });
+  });
+});