diff --git a/.env.example b/.env.example
index ff09942..407ed0c 100644
--- a/.env.example
+++ b/.env.example
@@ -18,7 +18,8 @@ KIMI_API_KEY=                 # kimi.com/code (Kimi 代码计划)
 # Aggregator platforms (optional)
 SILICONFLOW_API_KEY=          # siliconflow.cn
 OPENROUTER_API_KEY=           # openrouter.ai
-REQUESTY_API_KEY=             # requesty.ai — get a key at app.requesty.ai/api-keys (docs: docs.requesty.ai)
+REQUESTY_API_KEY=             # requesty.ai
+ATLASCLOUD_API_KEY=           # atlascloud.ai
 
 # Custom endpoints (optional)
 CUSTOM_OPENAI_API_KEY=       # OpenAI-compatible endpoint
diff --git a/EvoScientist/config/onboard/constants.py b/EvoScientist/config/onboard/constants.py
index 2f33cd9..134476e 100644
--- a/EvoScientist/config/onboard/constants.py
+++ b/EvoScientist/config/onboard/constants.py
@@ -30,6 +30,7 @@ VALID_PROVIDERS: frozenset[str] = frozenset(
         "nvidia",
         "siliconflow",
         "openrouter",
+        "atlascloud",
         "requesty",
         "custom-openai",
         "custom-anthropic",
diff --git a/EvoScientist/config/onboard/helpers.py b/EvoScientist/config/onboard/helpers.py
index 0426fca..dc789bd 100644
--- a/EvoScientist/config/onboard/helpers.py
+++ b/EvoScientist/config/onboard/helpers.py
@@ -15,6 +15,7 @@ from ..settings import EvoScientistConfig
 from .style import QMARK, WIZARD_STYLE, console
 from .validators import (
     validate_anthropic_key,
+    validate_atlascloud_key,
     validate_dashscope_code_key,
     validate_dashscope_key,
     validate_deepseek_key,
@@ -71,6 +72,11 @@ def _provider_key_info(config: EvoScientistConfig, provider: str):
             config.openrouter_api_key or os.environ.get("OPENROUTER_API_KEY", ""),
             validate_openrouter_key,
         ),
+        "atlascloud": (
+            "Atlas Cloud",
+            config.atlascloud_api_key or os.environ.get("ATLASCLOUD_API_KEY", ""),
+            validate_atlascloud_key,
+        ),
         "requesty": (
             "Requesty",
             config.requesty_api_key or os.environ.get("REQUESTY_API_KEY", ""),
diff --git a/EvoScientist/config/onboard/steps.py b/EvoScientist/config/onboard/steps.py
index 88fbbcd..ac3f164 100644
--- a/EvoScientist/config/onboard/steps.py
+++ b/EvoScientist/config/onboard/steps.py
@@ -296,6 +296,10 @@ def _step_provider(
             title="OpenRouter (aggregator — Grok, Gemini, Qwen, etc.)",
             value="openrouter",
         ),
+        Choice(
+            title="Atlas Cloud (aggregator — DeepSeek, Qwen, etc.)",
+            value="atlascloud",
+        ),
         Choice(
             title="Requesty (aggregator — OpenAI, Anthropic, Gemini, xAI, etc.)",
             value="requesty",
diff --git a/EvoScientist/config/onboard/validators.py b/EvoScientist/config/onboard/validators.py
index a61ac3d..0335c44 100644
--- a/EvoScientist/config/onboard/validators.py
+++ b/EvoScientist/config/onboard/validators.py
@@ -321,6 +321,49 @@ def validate_openrouter_key(api_key: str) -> tuple[bool, str]:
         return False, f"Error: {e}"
 
 
+def validate_atlascloud_key(api_key: str) -> tuple[bool, str]:
+    """Validate an Atlas Cloud key with a nonexistent sentinel model.
+
+    The probe deliberately targets a nonexistent sentinel model. A 404 means
+    authentication passed and model resolution failed; 200 also confirms
+    authentication if the sentinel unexpectedly resolves. A 401/403 means the
+    key was rejected. Other statuses remain inconclusive until verified.
+    """
+    if not api_key:
+        return True, "Skipped (no key provided)"
+
+    try:
+        import httpx
+
+        resp = httpx.post(
+            "https://api.atlascloud.ai/v1/chat/completions",
+            headers={
+                "Authorization": f"Bearer {api_key}",
+                "Content-Type": "application/json",
+            },
+            json={
+                "model": "atlascloud/auth-preflight",
+                "messages": [{"role": "user", "content": "ping"}],
+                "max_tokens": 1,
+            },
+            timeout=10,
+        )
+        if resp.status_code in (200, 404):
+            return True, "Valid"
+        # Atlas checks account balance before model resolution: a valid key
+        # on an uncredited account gets 402 from the sentinel probe.
+        if resp.status_code == 402:
+            return True, "Valid (insufficient balance — top up to use)"
+        if resp.status_code in (401, 403):
+            return False, "Invalid API key"
+        return False, f"Validation inconclusive (HTTP {resp.status_code})"
+    except Exception as e:
+        classified = _classify_validation_error(e)
+        if classified is not None:
+            return classified
+        return False, f"Error: {e}"
+
+
 def validate_requesty_key(api_key: str) -> tuple[bool, str]:
     """Validate a Requesty API key against the router's auth layer.
 
diff --git a/EvoScientist/config/onboard/wizard.py b/EvoScientist/config/onboard/wizard.py
index 9445e8b..ace7758 100644
--- a/EvoScientist/config/onboard/wizard.py
+++ b/EvoScientist/config/onboard/wizard.py
@@ -118,6 +118,7 @@ _PROVIDER_KEY_ATTR = {
     "google-genai": "google_api_key",
     "siliconflow": "siliconflow_api_key",
     "openrouter": "openrouter_api_key",
+    "atlascloud": "atlascloud_api_key",
     "requesty": "requesty_api_key",
     "deepseek": "deepseek_api_key",
     "zhipu": "zhipu_api_key",
diff --git a/EvoScientist/config/settings.py b/EvoScientist/config/settings.py
index 842d6fd..6f987a1 100644
--- a/EvoScientist/config/settings.py
+++ b/EvoScientist/config/settings.py
@@ -166,6 +166,7 @@ class EvoScientistConfig:
     minimax_base_url: str = ""
     siliconflow_api_key: str = ""
     openrouter_api_key: str = ""
+    atlascloud_api_key: str = ""
     requesty_api_key: str = ""
     deepseek_api_key: str = ""
     zhipu_api_key: str = ""
@@ -761,6 +762,7 @@ _ENV_MAPPINGS = {
     "minimax_base_url": "MINIMAX_BASE_URL",
     "siliconflow_api_key": "SILICONFLOW_API_KEY",
     "openrouter_api_key": "OPENROUTER_API_KEY",
+    "atlascloud_api_key": "ATLASCLOUD_API_KEY",
     "requesty_api_key": "REQUESTY_API_KEY",
     "deepseek_api_key": "DEEPSEEK_API_KEY",
     "zhipu_api_key": "ZHIPU_API_KEY",
@@ -939,6 +941,8 @@ def apply_config_to_env(config: EvoScientistConfig) -> None:
         os.environ["SILICONFLOW_API_KEY"] = config.siliconflow_api_key
     if config.openrouter_api_key and not os.environ.get("OPENROUTER_API_KEY"):
         os.environ["OPENROUTER_API_KEY"] = config.openrouter_api_key
+    if config.atlascloud_api_key and not os.environ.get("ATLASCLOUD_API_KEY"):
+        os.environ["ATLASCLOUD_API_KEY"] = config.atlascloud_api_key
     if config.requesty_api_key and not os.environ.get("REQUESTY_API_KEY"):
         os.environ["REQUESTY_API_KEY"] = config.requesty_api_key
     if config.deepseek_api_key and not os.environ.get("DEEPSEEK_API_KEY"):
diff --git a/EvoScientist/llm/errors.py b/EvoScientist/llm/errors.py
index d1f1114..4efa264 100644
--- a/EvoScientist/llm/errors.py
+++ b/EvoScientist/llm/errors.py
@@ -176,6 +176,7 @@ def _redact_api_keys(message: str) -> str:
 _HOST_TO_PROVIDER: dict[str, str] = {
     "api.openai.com": "openai",
     "api.anthropic.com": "anthropic",
+    "api.atlascloud.ai": "atlascloud",
     "api.deepseek.com": "deepseek",
     "api.moonshot.cn": "moonshot",
     "api.siliconflow.cn": "siliconflow",
diff --git a/EvoScientist/llm/models.py b/EvoScientist/llm/models.py
index 6d1fa6a..50f1610 100644
--- a/EvoScientist/llm/models.py
+++ b/EvoScientist/llm/models.py
@@ -1,9 +1,9 @@
 """LLM model configuration based on LangChain init_chat_model.
 
 This module provides a unified interface for creating chat model instances
-with support for multiple providers (Anthropic, OpenAI, Google GenAI, MiniMax
-(Anthropic-compatible), NVIDIA, SiliconFlow, OpenRouter, Requesty, ZhipuAI,
-Volcengine, DashScope, DashScope-Code, DeepSeek, Ollama, and custom
+with support for multiple providers (Anthropic, OpenAI, Google GenAI, Atlas
+Cloud, MiniMax (Anthropic-compatible), NVIDIA, SiliconFlow, OpenRouter, Requesty,
+ZhipuAI, Volcengine, DashScope, DashScope-Code, DeepSeek, Ollama, and custom
 OpenAI/Anthropic-compatible endpoints) and convenient short names for common
 models.
 """
@@ -46,6 +46,7 @@ _VOLCENGINE_BASE_URL = "https://ark.cn-beijing.volces.com/api/v3"
 _DASHSCOPE_BASE_URL = "https://dashscope.aliyuncs.com/compatible-mode/v1"
 _DASHSCOPE_CODE_BASE_URL = "https://coding.dashscope.aliyuncs.com/v1"
 
+_ATLASCLOUD_BASE_URL = "https://api.atlascloud.ai/v1"
 _MOONSHOT_BASE_URL = "https://api.moonshot.cn/v1"
 _KIMI_CODING_BASE_URL = "https://api.kimi.com/coding/"
 _REQUESTY_BASE_URL = "https://router.requesty.ai/v1"
@@ -107,6 +108,7 @@ def _is_deepseek_endpoint(base_url: str | None) -> bool:
 # Providers routed through the OpenAI provider with a custom base_url.
 # Maps provider name → (base_url or None, env var for API key).
 _OPENAI_ROUTED_PROVIDERS: dict[str, tuple[str | None, str]] = {
+    "atlascloud": (_ATLASCLOUD_BASE_URL, "ATLASCLOUD_API_KEY"),
     "moonshot": (_MOONSHOT_BASE_URL, "MOONSHOT_API_KEY"),
     "siliconflow": (_SILICONFLOW_BASE_URL, "SILICONFLOW_API_KEY"),
     "zhipu": (_ZHIPU_BASE_URL, "ZHIPU_API_KEY"),
@@ -171,6 +173,8 @@ _MODEL_ENTRIES: list[tuple[str, str, str]] = [
     ("gpt-5.4", "gpt-5.4", "custom-openai"),
     ("gpt-5.3-codex", "gpt-5.3-codex", "custom-openai"),
     ("gpt-5-mini", "gpt-5-mini", "custom-openai"),
+    # Atlas Cloud (OpenAI-compatible)
+    ("qwen3.5-27b", "qwen/qwen3.5-27b", "atlascloud"),
     # Anthropic (current generation)
     ("claude-fable-5", "claude-fable-5", "anthropic"),
     ("claude-opus-5", "claude-opus-5", "anthropic"),
diff --git a/tests/test_config.py b/tests/test_config.py
index 0301547..ad912e9 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -57,6 +57,7 @@ def temp_config_dir(tmp_path, monkeypatch):
     for key in [
         "ANTHROPIC_API_KEY",
         "OPENAI_API_KEY",
+        "ATLASCLOUD_API_KEY",
         "TAVILY_API_KEY",
         "EVOSCIENTIST_DEFAULT_MODE",
         "EVOSCIENTIST_WORKSPACE_DIR",
@@ -87,6 +88,7 @@ def clean_env(monkeypatch):
     for key in [
         "ANTHROPIC_API_KEY",
         "OPENAI_API_KEY",
+        "ATLASCLOUD_API_KEY",
         "TAVILY_API_KEY",
         "EVOSCIENTIST_DEFAULT_MODE",
         "EVOSCIENTIST_WORKSPACE_DIR",
@@ -713,6 +715,7 @@ class TestApplyConfigToEnv:
         config = EvoScientistConfig(
             anthropic_api_key="config-ant-key",
             openai_api_key="config-oai-key",
+            atlascloud_api_key="config-atlas-key",
             tavily_api_key="config-tav-key",
         )
 
@@ -720,6 +723,7 @@ class TestApplyConfigToEnv:
 
         assert os.environ.get("ANTHROPIC_API_KEY") == "config-ant-key"
         assert os.environ.get("OPENAI_API_KEY") == "config-oai-key"
+        assert os.environ.get("ATLASCLOUD_API_KEY") == "config-atlas-key"
         assert os.environ.get("TAVILY_API_KEY") == "config-tav-key"
 
     def test_does_not_override_existing_env(self, monkeypatch):
@@ -738,6 +742,7 @@ class TestApplyConfigToEnv:
 
         assert os.environ.get("ANTHROPIC_API_KEY") is None
         assert os.environ.get("OPENAI_API_KEY") is None
+        assert os.environ.get("ATLASCLOUD_API_KEY") is None
         assert os.environ.get("EVOSCIENTIST_OPENROUTER_ANTHROPIC_PROMPT_CACHE") is None
 
     def test_openrouter_anthropic_prompt_cache_opt_out_applied(
diff --git a/tests/test_llm.py b/tests/test_llm.py
index 6b31380..fb5c935 100644
--- a/tests/test_llm.py
+++ b/tests/test_llm.py
@@ -46,6 +46,7 @@ class TestModelsRegistry:
         assert "deepseek" in providers
         assert "moonshot" in providers
         assert "kimi-coding" in providers
+        assert "atlascloud" in providers
 
     def test_entries_are_valid_tuples(self):
         """Test that _MODEL_ENTRIES contains valid (name, model_id, provider) tuples."""
@@ -68,6 +69,7 @@ class TestModelsRegistry:
             "deepseek",
             "moonshot",
             "kimi-coding",
+            "atlascloud",
         }
         for entry in _MODEL_ENTRIES:
             assert len(entry) == 3, f"Entry {entry} doesn't have 3 elements"
@@ -91,6 +93,9 @@ class TestModelsRegistry:
         assert len(openrouter_models) > 0
         siliconflow_models = get_models_for_provider("siliconflow")
         assert len(siliconflow_models) > 0
+        atlas_models = get_models_for_provider("atlascloud")
+        assert ("qwen3.5-27b", "qwen/qwen3.5-27b") in atlas_models
+        assert get_models_for_provider("atlas") == []
 
 
 # =============================================================================
@@ -390,6 +395,30 @@ def _sdk_retry_supports_status_codes_override() -> bool:
 
 
 class TestThirdPartyRouting:
+    @patch("EvoScientist.llm.models.init_chat_model")
+    def test_atlascloud_routes_through_openai(self, mock_init, monkeypatch):
+        """Atlas Cloud should use OpenAI-compatible routing with its default URL."""
+        mock_init.return_value = "mock_model"
+        monkeypatch.setenv("ATLASCLOUD_API_KEY", "atlas-key-123")
+
+        get_chat_model("qwen3.5-27b", provider="atlascloud")
+
+        call_kwargs = mock_init.call_args[1]
+        assert call_kwargs["model"] == "qwen/qwen3.5-27b"
+        assert call_kwargs["model_provider"] == "openai"
+        assert call_kwargs["base_url"] == "https://api.atlascloud.ai/v1"
+        assert call_kwargs["api_key"] == "atlas-key-123"
+        assert "reasoning" not in call_kwargs
+
+    def test_atlascloud_host_maps_to_provider(self):
+        """Provider error envelopes should identify Atlas Cloud by host."""
+        from EvoScientist.llm.errors import _lookup_host_or_compat
+
+        assert (
+            _lookup_host_or_compat("https://api.atlascloud.ai/v1", "openai")
+            == "atlascloud"
+        )
+
     @patch("EvoScientist.llm.models.init_chat_model")
     def test_siliconflow_routes_through_openai(self, mock_init, monkeypatch):
         """SiliconFlow provider should route through OpenAI with correct base_url."""
diff --git a/tests/test_onboard.py b/tests/test_onboard.py
index 2d7c233..dcc8c88 100644
--- a/tests/test_onboard.py
+++ b/tests/test_onboard.py
@@ -373,6 +373,62 @@ class TestChoiceValidator:
         assert "one of" in str(exc_info.value.message)
 
 
+class TestValidateAtlasCloudKey:
+    def test_empty_key_skipped(self):
+        from EvoScientist.config.onboard.validators import validate_atlascloud_key
+
+        is_valid, msg = validate_atlascloud_key("")
+        assert is_valid is True
+        assert "Skipped" in msg
+
+    @pytest.mark.parametrize("status", [200, 404])
+    def test_accepts_authenticated_sentinel_statuses(self, status):
+        from EvoScientist.config.onboard.validators import validate_atlascloud_key
+
+        with patch("httpx.post") as mock_post:
+            mock_post.return_value.status_code = status
+            is_valid, msg = validate_atlascloud_key("atlas-key")
+
+        assert is_valid is True
+        assert msg == "Valid"
+        payload = mock_post.call_args.kwargs["json"]
+        assert payload["model"] == "atlascloud/auth-preflight"
+        assert payload["max_tokens"] == 1
+
+    @pytest.mark.parametrize("status", [401, 403])
+    def test_auth_rejection_is_invalid(self, status):
+        from EvoScientist.config.onboard.validators import validate_atlascloud_key
+
+        with patch("httpx.post") as mock_post:
+            mock_post.return_value.status_code = status
+            is_valid, msg = validate_atlascloud_key("bad-key")
+
+        assert is_valid is False
+        assert msg == "Invalid API key"
+
+    def test_insufficient_balance_means_valid_key(self):
+        """402 fires before model resolution, so auth passed — key is valid."""
+        from EvoScientist.config.onboard.validators import validate_atlascloud_key
+
+        with patch("httpx.post") as mock_post:
+            mock_post.return_value.status_code = 402
+            is_valid, msg = validate_atlascloud_key("atlas-key")
+
+        assert is_valid is True
+        assert "insufficient balance" in msg.lower()
+
+    @pytest.mark.parametrize("status", [400, 429, 500, 503])
+    def test_transient_status_is_inconclusive(self, status):
+        from EvoScientist.config.onboard.validators import validate_atlascloud_key
+
+        with patch("httpx.post") as mock_post:
+            mock_post.return_value.status_code = status
+            is_valid, msg = validate_atlascloud_key("atlas-key")
+
+        assert is_valid is False
+        assert "inconclusive" in msg.lower()
+
+
 # =============================================================================
 # Test Step Functions (Mocked questionary)
 # =============================================================================