chore: remove async for upsert/delete/append in python

bindings/python/fluss/__init__.pyi

@@ -301,13 +301,16 @@ class FlussTable:
     def __repr__(self) -> str: ...
 
 class AppendWriter:
-    async def append(self, row: dict | list | tuple) -> None:
+    def append(self, row: dict | list | tuple) -> WriteResultHandle:
         """Append a single row to the table.
 
         Args:
             row: Dictionary mapping field names to values, or
                  list/tuple of values in schema order
 
+        Returns:
+            WriteResultHandle: Ignore for fire-and-forget, or await handle.wait() for acknowledgement.
+
         Supported Types:
             Currently supports primitive types only:
             - Boolean, TinyInt, SmallInt, Int, BigInt (integers)
@@ -319,24 +322,24 @@ class AppendWriter:
             Temporal types (Date, Timestamp, Decimal) are not yet supported.
 
         Example:
-            await writer.append({'id': 1, 'name': 'Alice', 'score': 95.5})
-            await writer.append([1, 'Alice', 95.5])
+            writer.append({'id': 1, 'name': 'Alice', 'score': 95.5})
+            writer.append([1, 'Alice', 95.5])
 
         Note:
             For high-throughput bulk loading, prefer write_arrow_batch().
             Use flush() to ensure all queued records are sent and acknowledged.
         """
         ...
     def write_arrow(self, table: pa.Table) -> None: ...
-    def write_arrow_batch(self, batch: pa.RecordBatch) -> None: ...
+    def write_arrow_batch(self, batch: pa.RecordBatch) -> WriteResultHandle: ...
     def write_pandas(self, df: pd.DataFrame) -> None: ...
-    def flush(self) -> None: ...
+    async def flush(self) -> None: ...
     def __repr__(self) -> str: ...
 
 class UpsertWriter:
     """Writer for upserting and deleting data in a Fluss primary key table."""
 
-    async def upsert(self, row: dict | list | tuple) -> None:
+    def upsert(self, row: dict | list | tuple) -> WriteResultHandle:
         """Upsert a row into the table.
 
         If a row with the same primary key exists, it will be updated.
@@ -345,21 +348,37 @@ class UpsertWriter:
         Args:
             row: Dictionary mapping field names to values, or
                  list/tuple of values in schema order
+
+        Returns:
+            WriteResultHandle: Ignore for fire-and-forget, or await handle.wait() for ack.
         """
         ...
-    async def delete(self, pk: dict | list | tuple) -> None:
+    def delete(self, pk: dict | list | tuple) -> WriteResultHandle:
         """Delete a row from the table by primary key.
 
         Args:
             pk: Dictionary with PK column names as keys, or
                 list/tuple of PK values in PK column order
+
+        Returns:
+            WriteResultHandle: Ignore for fire-and-forget, or await handle.wait() for ack.
         """
         ...
     async def flush(self) -> None:
         """Flush all pending upsert/delete operations to the server."""
         ...
     def __repr__(self) -> str: ...
 
+
+class WriteResultHandle:
+    """Handle for a pending write (append/upsert/delete). Ignore for fire-and-forget, or await handle.wait() for ack."""
+
+    async def wait(self) -> None:
+        """Wait for server acknowledgment of this write."""
+        ...
+    def __repr__(self) -> str: ...
+
+
 class Lookuper:
     """Lookuper for performing primary key lookups on a Fluss table."""