feat(protobuf): add unified state helpers for oauth payloads

src/tests/unit/protobuf-unified.test.ts

@@ -30,4 +30,36 @@ describe('ProtobufUtils Unified OAuth', () => {
       refreshToken,
     });
   });
+
+  it('should round-trip unified state entry with topic/row structure', () => {
+    const payload = new Uint8Array([1, 2, 3, 4, 5]);
+    const entry = ProtobufUtils.createUnifiedStateEntry('userStatusSentinelKey', payload);
+    const decoded = ProtobufUtils.decodeUnifiedStateEntry(entry);
+
+    expect(decoded.sentinelKey).toBe('userStatusSentinelKey');
+    expect(Array.from(decoded.payload)).toEqual([1, 2, 3, 4, 5]);
+  });
+
+  it('should parse legacy nested unified oauth payload', () => {
+    const accessToken = 'legacy-access';
+    const refreshToken = 'legacy-refresh';
+    const oauthInfo = ProtobufUtils.createOAuthInfo(accessToken, refreshToken, 1700000000);
+    const oauthInfoB64 = Buffer.from(oauthInfo).toString('base64');
+
+    // Legacy nested structure:
+    // Outer(F1) -> Inner(F1 sentinel, F2 Inner2), Inner2(F1 base64(oauthInfo))
+    const inner2 = ProtobufUtils.encodeStringField(1, oauthInfoB64);
+    const inner = new Uint8Array(
+      ProtobufUtils.encodeStringField(1, 'oauthTokenInfoSentinelKey').length +
+        ProtobufUtils.encodeLenDelimField(2, inner2).length,
+    );
+    const innerField1 = ProtobufUtils.encodeStringField(1, 'oauthTokenInfoSentinelKey');
+    const innerField2 = ProtobufUtils.encodeLenDelimField(2, inner2);
+    inner.set(innerField1, 0);
+    inner.set(innerField2, innerField1.length);
+    const legacyOuter = ProtobufUtils.encodeLenDelimField(1, inner);
+
+    const parsed = ProtobufUtils.extractOAuthTokenInfoFromUnifiedState(legacyOuter);
+    expect(parsed).toEqual({ accessToken, refreshToken });
+  });
 });