diff --git a/packages/core/tests/msg-push-handler.test.ts b/packages/core/tests/msg-push-handler.test.ts
index 3e7d9ab5..33606ecc 100644
--- a/packages/core/tests/msg-push-handler.test.ts
+++ b/packages/core/tests/msg-push-handler.test.ts
@@ -181,9 +181,20 @@ describe('parseMsgPush group member increase', () => {
       ),
       identity,
     ) as GroupMemberJoin[];
+    const [unknownHighBits] = parseMsgPush(
+      makeGroupIncreasePacket(
+        member.uid,
+        operator.uid,
+        GROUP_ID,
+        Buffer.from(operator.uid, 'utf8'),
+        0x103,
+      ),
+      identity,
+    ) as GroupMemberJoin[];
 
     expect(approved.joinType).toBe('approve');
     expect(invited.joinType).toBe('invite');
+    expect(unknownHighBits.joinType).toBe('approve');
   });
 
   it('reports malformed raw operator bytes with bounded context', () => {
diff --git a/packages/protocol/src/msg-push/decoders/group-member-change.ts b/packages/protocol/src/msg-push/decoders/group-member-change.ts
index c94a5b1d..263de7ae 100644
--- a/packages/protocol/src/msg-push/decoders/group-member-change.ts
+++ b/packages/protocol/src/msg-push/decoders/group-member-change.ts
@@ -5,11 +5,12 @@ import { decodeNestedOperatorUid, decodeRawOperatorUid, resolveUidToUin } from '
 import type { MsgPushDecoder } from '../registry';
 
 function joinTypeFromOperationType(raw: number): NonNullable<GroupMemberJoin['joinType']> {
-  // QQ sets the high bit on the PkgType=33 operation code. After normalizing
-  // it, code 3 means an invitation; code 2 (and unknown/absent values) means
-  // approval. Do not use the nested `join_type`: that is an invitation-source
-  // enum rather than OneBot's approve/invite distinction.
-  return (raw & 0x7f) === 3 ? 'invite' : 'approve';
+  // QQ uses bit 0x80 as a flag on the PkgType=33 operation code. Clear only
+  // that bit: other high bits remain significant in the native handler. The
+  // normalized code 3 means an invitation; all other values mean approval.
+  // Do not use the nested `join_type`: that is an invitation-source enum.
+  const normalized = raw - (raw & 0x80);
+  return normalized === 3 ? 'invite' : 'approve';
 }
 
 export const decodeGroupMemberJoin: MsgPushDecoder = (ctx) => {