diff --git a/crawl4ai/async_webcrawler.py b/crawl4ai/async_webcrawler.py
index dbdce057d..1806004e8 100644
--- a/crawl4ai/async_webcrawler.py
+++ b/crawl4ai/async_webcrawler.py
@@ -1275,8 +1275,11 @@ async def amap_domain(
                 base_directory=self.crawl4ai_folder,
             )
 
-        mapper_config = config.clone(**kwargs) if config and kwargs else (
-            config or DomainMapperConfig(**kwargs) if kwargs else DomainMapperConfig()
-        )
+        if config is None:
+            mapper_config = DomainMapperConfig(**kwargs)
+        elif kwargs:
+            mapper_config = config.clone(**kwargs)
+        else:
+            mapper_config = config
 
         return await self._domain_mapper.scan(domain, mapper_config)
\ No newline at end of file
diff --git a/tests/test_amap_domain_config.py b/tests/test_amap_domain_config.py
new file mode 100644
index 000000000..dbfbb1cfb
--- /dev/null
+++ b/tests/test_amap_domain_config.py
@@ -0,0 +1,105 @@
+"""Regression tests for the public domain mapper configuration boundary."""
+
+import asyncio
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from crawl4ai import AsyncWebCrawler
+from crawl4ai.async_configs import DomainMapperConfig
+
+
+@pytest.mark.parametrize("initialized", [False, True])
+def test_amap_domain_preserves_explicit_config(tmp_path, initialized):
+    config = DomainMapperConfig(
+        source="sitemap",
+        max_urls=3,
+        concurrency=1,
+        include_subdomains=False,
+        extract_head=False,
+        http_timeout=2.0,
+    )
+    expected = [{"url": "https://example.com/docs"}]
+    mapper = AsyncMock()
+    mapper.scan.return_value = expected
+    crawler = AsyncWebCrawler(base_directory=str(tmp_path))
+    if initialized:
+        crawler._domain_mapper = mapper
+
+    with patch(
+        "crawl4ai.async_webcrawler.DomainMapper", return_value=mapper
+    ) as factory:
+        result = asyncio.run(crawler.amap_domain("example.com", config=config))
+
+    mapper.scan.assert_awaited_once_with("example.com", config)
+    assert result is expected
+    if initialized:
+        factory.assert_not_called()
+    else:
+        factory.assert_called_once_with(
+            logger=crawler.logger, base_directory=crawler.crawl4ai_folder
+        )
+
+
+def test_amap_domain_overrides_without_mutating_config(tmp_path):
+    config = DomainMapperConfig(source="sitemap", max_urls=3, include_subdomains=False)
+    original = config.to_dict()
+    mapper = AsyncMock()
+    crawler = AsyncWebCrawler(base_directory=str(tmp_path))
+    crawler._domain_mapper = mapper
+
+    asyncio.run(crawler.amap_domain("example.com", config=config, max_urls=2))
+
+    actual = mapper.scan.await_args.args[1]
+    assert actual is not config
+    assert actual.to_dict() == {**original, "max_urls": 2}
+    assert config.to_dict() == original
+
+
+def test_amap_domain_builds_config_from_kwargs(tmp_path):
+    mapper = AsyncMock()
+    crawler = AsyncWebCrawler(base_directory=str(tmp_path))
+    crawler._domain_mapper = mapper
+
+    asyncio.run(
+        crawler.amap_domain(
+            "example.com", source="feed", max_urls=4, include_subdomains=False
+        )
+    )
+
+    actual = mapper.scan.await_args.args[1]
+    assert (
+        actual.to_dict()
+        == DomainMapperConfig(
+            source="feed", max_urls=4, include_subdomains=False
+        ).to_dict()
+    )
+
+
+def test_amap_domain_creates_fresh_default_configs(tmp_path):
+    mapper = AsyncMock()
+    crawler = AsyncWebCrawler(base_directory=str(tmp_path))
+    crawler._domain_mapper = mapper
+
+    asyncio.run(crawler.amap_domain("example.com"))
+    asyncio.run(crawler.amap_domain("example.org", config=None))
+
+    first = mapper.scan.await_args_list[0].args[1]
+    second = mapper.scan.await_args_list[1].args[1]
+    assert first is not second
+    assert first.to_dict() == second.to_dict() == DomainMapperConfig().to_dict()
+
+
+def test_amap_domain_propagates_scan_errors(tmp_path):
+    error = ValueError("invalid discovery source")
+    mapper = AsyncMock()
+    mapper.scan.side_effect = error
+    crawler = AsyncWebCrawler(base_directory=str(tmp_path))
+    crawler._domain_mapper = mapper
+    config = DomainMapperConfig(source="invalid")
+
+    with pytest.raises(ValueError) as raised:
+        asyncio.run(crawler.amap_domain("example.com", config=config))
+
+    assert raised.value is error
+    mapper.scan.assert_awaited_once_with("example.com", config)