diff --git a/tests/test_webui_env_preflight.py b/tests/test_webui_env_preflight.py
new file mode 100644
index 0000000..5b84d86
--- /dev/null
+++ b/tests/test_webui_env_preflight.py
@@ -0,0 +1,89 @@
+import pytest
+import yaml
+
+pytest.importorskip("gradio")
+
+from skillopt_webui import app as webui_app
+
+
+def _write_config(tmp_path, model):
+    config_path = tmp_path / "config.yaml"
+    config_path.write_text(
+        yaml.safe_dump({
+            "model": model,
+            "env": {"name": "searchqa"},
+        }),
+        encoding="utf-8",
+    )
+    return str(config_path)
+
+
+def test_build_training_env_loads_project_dotenv(tmp_path, monkeypatch):
+    monkeypatch.setattr(webui_app, "PROJECT_ROOT", tmp_path)
+    (tmp_path / ".env").write_text(
+        "\n".join([
+            "export QWEN_CHAT_BASE_URL=http://qwen.example/v1",
+            "QWEN_CHAT_MODEL=test-model",
+            "QWEN_CHAT_API_KEY='secret-value'",
+        ]),
+        encoding="utf-8",
+    )
+
+    env = webui_app.build_training_env()
+
+    assert env["QWEN_CHAT_BASE_URL"] == "http://qwen.example/v1"
+    assert env["QWEN_CHAT_MODEL"] == "test-model"
+    assert env["QWEN_CHAT_API_KEY"] == "secret-value"
+
+
+def test_preflight_reports_missing_openai_chat_endpoint(tmp_path, monkeypatch):
+    monkeypatch.delenv("AZURE_OPENAI_ENDPOINT", raising=False)
+    monkeypatch.delenv("OPTIMIZER_AZURE_OPENAI_ENDPOINT", raising=False)
+    monkeypatch.delenv("TARGET_AZURE_OPENAI_ENDPOINT", raising=False)
+    config_path = _write_config(
+        tmp_path,
+        {
+            "backend": "qwen",
+            "optimizer_backend": "openai_chat",
+            "target_backend": "openai_chat",
+        },
+    )
+
+    error = webui_app.validate_training_config(config_path, {})
+
+    assert "missing Azure/OpenAI-compatible endpoint for optimizer, target" in error
+    assert "model.backend is qwen" in error
+
+
+def test_preflight_reports_unreachable_qwen_endpoint(tmp_path, monkeypatch):
+    monkeypatch.setattr(webui_app, "_can_connect_to_url", lambda _url: False)
+    config_path = _write_config(
+        tmp_path,
+        {
+            "backend": "qwen",
+            "optimizer_backend": "qwen_chat",
+            "target_backend": "qwen_chat",
+            "qwen_chat_base_url": "http://127.0.0.1:9/v1",
+        },
+    )
+
+    error = webui_app.validate_training_config(config_path, {})
+
+    assert "cannot connect to qwen_chat endpoint" in error
+    assert "127.0.0.1:9" in error
+
+
+def test_preflight_accepts_reachable_qwen_endpoint(tmp_path, monkeypatch):
+    seen_urls = []
+    monkeypatch.setattr(webui_app, "_can_connect_to_url", lambda url: seen_urls.append(url) or True)
+    config_path = _write_config(
+        tmp_path,
+        {
+            "optimizer_backend": "qwen_chat",
+            "target_backend": "qwen_chat",
+            "qwen_chat_base_url": "http://qwen.example/v1",
+        },
+    )
+
+    assert webui_app.validate_training_config(config_path, {}) is None
+    assert seen_urls == ["http://qwen.example/v1", "http://qwen.example/v1"]