diff --git a/tests/test_litigation_providers.py b/tests/test_litigation_providers.py
new file mode 100644
index 0000000..3afe4ba
--- /dev/null
+++ b/tests/test_litigation_providers.py
@@ -0,0 +1,66 @@
+"""Regression tests for litigation provider factory."""
+
+from __future__ import annotations
+
+import os
+
+import pytest
+
+from litigation.providers.factory import get_provider
+from litigation.providers.ollama_provider import OllamaProvider
+from litigation.providers.openai_compat_provider import OpenAICompatProvider
+
+
+def test_get_provider_ollama() -> None:
+    provider = get_provider("ollama", "llama3", ollama_base_url="http://127.0.0.1:11434")
+    assert isinstance(provider, OllamaProvider)
+    assert provider.model == "llama3"
+    assert provider.base_url == "http://127.0.0.1:11434"
+
+
+def test_get_provider_lm_studio() -> None:
+    provider = get_provider("lm_studio", "local-model", lm_studio_base_url="http://127.0.0.1:1234/v1")
+    assert isinstance(provider, OpenAICompatProvider)
+    assert provider.model == "local-model"
+    assert provider.base_url == "http://127.0.0.1:1234/v1"
+    assert provider.api_key == "lm-studio"
+
+
+def test_get_provider_openrouter_with_explicit_key() -> None:
+    provider = get_provider(
+        "openrouter",
+        "anthropic/claude-3.5-sonnet",
+        openrouter_api_key="sk-test",
+        openrouter_config={
+            "app_attribution": {
+                "http_referer": "https://example.test",
+                "x_title": "Test App",
+            },
+            "provider": {"sort": "price"},
+            "user": "user-42",
+        },
+    )
+    assert isinstance(provider, OpenAICompatProvider)
+    assert provider.api_key == "sk-test"
+    assert provider.default_headers == {
+        "HTTP-Referer": "https://example.test",
+        "X-Title": "Test App",
+    }
+    assert provider.extra_body == {"provider": {"sort": "price"}, "user": "user-42"}
+
+
+def test_get_provider_openrouter_reads_env_key(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("OPENROUTER_API_KEY", "env-key")
+    provider = get_provider("openrouter", "openai/gpt-4o-mini")
+    assert provider.api_key == "env-key"
+
+
+def test_get_provider_openrouter_missing_key_raises(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("OPENROUTER_API_KEY", raising=False)
+    with pytest.raises(ValueError, match="OPENROUTER_API_KEY"):
+        get_provider("openrouter", "openai/gpt-4o-mini")
+
+
+def test_get_provider_unknown_raises() -> None:
+    with pytest.raises(ValueError, match="Unknown provider"):
+        get_provider("azure", "gpt-4")